TRADITIONAL POSTER - ISMRM - Levo infiltration

TRADITIONAL POSTER

Give the Dog a Bone

Hall B Monday 14:00-16:00

784. Preliminary In-Vivo Bone Quantification Results Using MR and PQCT

Victor Rakesh Lazar1, Gary P. Liney2, David J. Manton1, Peter Gibbs1, Martin Lowry1, Celia L. Gregson3, Joern Rittweger4, Sue Steel5, Chris Langton6, J H. Tobias3, Lindsay W. Turnbull1

1Centre for MR Investigations, University of Hull, Hull, North Humberside, United Kingdom; 2Radiotherapy Physics, University of Hull, Hull, North Humberside, United Kingdom; 3Academic Rheumatology, University of Bristol, Bristol, United Kingdom; 4Excercise and Sports Medicine, Manchester Metropolitan University, Manchester, United Kingdom; 5Centre for Metabolic Bone Disease, Hull Royal Infirmary, Hull, North Humberside, United Kingdom; 6School of Physical and Chemical Sciences, Queensland University of Technology, Australia

Bone quantification is commonly measured using DEXA and pQCT. Research in MRI and MRS have shown promising potential in the quantification of bones. Our work was based on using these ideas in a clinical setting on individual patients. The work was involved in a High Bone Mass (HBM) study program to identify individuals affected with a genetic condition of LRP–5. pQCT data was collected from 169 individuals from the HBM study. 43 people were selected for MRI and MRS acquisition from the total pQCT population. Preliminary results from these investigations have been explained in this abstract.

785. Software Tools for MR and PQCT Bone Quantification

Victor Rakesh Lazar1, Gary P. Liney2, David J. Manton1, Peter Gibbs1, Martin Lowry1, Celia L. Gregson3, Joern Rittweger4, Sue Steel5, Chris Langton6, J H. Tobias3, Lindsay W. Turnbull1

1Centre for MR Investigations, University of Hull, Hull, North Humberside, United Kingdom; 2Radiotherapy Physics, University of Hull, Hull, North Humberside, United Kingdom; 3Academic Rheumatology, University of Bristol, Bristol, United Kingdom; 4Excercise and Sports Medicine, Manchester Metropolitan University, Manchester, United Kingdom; 5Centre for Metabolic Bone Disease, Hull Royal Infirmary, Hull, United Kingdom; 6School of Physical and Chemical Sciences, Queensland University of Technology, Australia

Peripheral Quantitative Computed Tomography (pQCT) and Dual Energy X-Ray Absorptiometry (DEXA) are the current gold standards for the measurement of bone density and structure, in the research and clinical setting respectively. However, Magnetic Resonance Imaging (MRI) and unsuppressed 1H Magnetic Resonance Spectroscopy (MRS) can also offer several advantages including the ability to quantify bone marrow content and structure. In-house software was developed to process and evaluate cortical and trabecular bone structure, marrow composition and vertebrae segmentation using data from MRI/MRS and structural details from pQCT.

786. Characterization of Bone Explants by Magnetic Resonance Microscopy

Ingrid E. Chesnick1, Carol B. Fowler1, Francis A. Avallone2, Kimberlee Potter1

1Department of Biophysics, Armed Forces Institute of Pathology Annex, Rockville, MD, United States; 2Department of Genitourinary Pathology, Armed Forces Institute of Pathology, Washington, DC, United States

MRI studies of tissue engineered constructs prior to implantation clearly demonstrate the utility of the MRI technique for monitoring the bone formation process. However, in our studies of osteoblast-seeded scaffolds, implanted on the chorioallantoic membrane of a chick embryo, we have found that the presence of angiogenic vessels and fibrous tissue around the implant can confound MRI findings of bone deposition. On-going studies support the use of targeted contrast agents for studying mineral deposition and blood vessel infiltration in tissue engineered scaffolds post-implantation.

787. Performance of 7T µMRI-Based Virtual Bone Biopsy for Structural and Mechanical Analysis at the Distal Tibia

Yusuf Abu Tayeb Bhagat1, Chamith S. Rajapakse1, James H. Love1, Michael J. Wald1, Jeremy F. Magland1, Alexander C. Wright1, Hee Kwon Song1, Felix W. Wehrli1

1Laboratory for Structural NMR Imaging, University of Pennsylvania, Philadelphia, PA, United States

The detection of subtle microstructural trabecular bone (TB) alterations such as the conversion of plates to rods requires adequate signal-to-noise ratio (SNR), which governs achievable spatial resolution and scan time. Increased SNR may enhance detection sensitivity for microstructural changes in treatment studies. Here, the reproducibility of TB quantitative parameters was investigated using a new 3D fast-spin-echo technique at 7.0T. The imaging and analysis protocol is shown to provide highly reproducible measures of scale, topology and mechanical parameters related to TB microstructure. Performance improvements relative to earlier work are attributed to enhanced SNR, motion control and correction, and improved registration techniques.

788. Studying the Effect of Different Biomaterials on Healing Process in Bone Injury Model Using Microscopic MRI and Micro CT

May Abdel Hamid Taha1, Sarah L. Manske2, Erika Kristensen3, Jaymi T. Taiani4, Roman Krawetz5, Ying Wu, Steven K. Boyd6, John Robert Matyas7, Derrick E. Rancourt5, Jeffery F. Dunn1

1Radiology, University of Calgary, Calgary, Alberta, Canada; 2Kinesiology; 3Mechanical and Manufacturing Engineering; 4 Medical Sciences; 5Departments of Oncology, Biochemistry & Molecular Biology and Medical Genetics; 6Mechanical and Manufacturing Engineering; 7Comparative Biology and Experimental Medicine in Veterinary Medicine, University of Calgary, Calgary, Alberta, Canada

The objective of this study was to investigate the effect of different biomaterials on bone healing in vivo in a mouse model of bone injury. These materials; matrigel, purecol gel and hydroxyapatite (HA) are potential matrices to support stem cells. Optimized in vivo MR microscopy and micro computed tomography were used to assess fracture repair. In addition, MRI images and µCT scans were compared at the same time point, to show the difference between them in revealing the actual stage of healing.

789. Traditional Bone Structural Parameters on Different Resolutions in Magnetic Resonance Imaging

June-Goo Lee1,2, Gyunggoo Cho1, Youngkyu Song1, Jong Hyo Kim2, Namkug Kim3

1Division of Proteome Research/Bio-Magnetic Resonance Research Center, Korea Basic Science Institute, Cheongwon-Gun, Chungcheongbuk-Do, Korea, Republic of; 2Interdisciplinary Program in Radiation Applied Life Science, Seoul National University College of Medicine, Seoul, Korea, Republic of; 3Department of Radiology, Asan Medical Center, University of Ulsan, Seoul, Korea, Republic of

Our study focused on the development of robust image processing algorithm on low resolution μ-MR bone image

790. Advanced Image Analysis Techniques of New High-Resolution Images of the Proximal Femur in the Presence of Red and Yellow Bone Marrow Using Local Bone Enhancement Fuzzy Clustering

Jenny Folkesson1, Julio Carballido-Gamio1, Dimitrios C. Karampinos1, Patrick Koon2, Suchandrima Banerjee2, Eric Han2, Thomas M. Link1, Sharmila Majumdar1, Roland Krug1

1Radiology and Biomedical Imaging, University of California, San Francisco, CA, United States; 2Applied Science Laboratory, GE Heathcare, Menlo Park, CA, United States

With the advent of new MR hardware and pulse sequences it is now possible to image the small trabecular structure of deeper seated regions like the proximal femur with high spatial resolution in a clinically feasible scan time. We employ a novel partial membership bone segmentation technique (BE-FCM) technique that enhances bone segmentation compared to an established dual thresholding method in the presence of signal variations due to different marrow types. We demonstrate that the new image acquisition and analysis framework enables trabecular bone analysis in the deeply situated femoral head, something which has been previously unfeasible in vivo.

791. Bone Marrow Fat Fraction Mapping in the Proximal Femur in Vivo Using IDEAL Gradient Echo Imaging

Dimitrios C. Karampinos1, Huanzhou Yu2, Ann Shimakawa2, Eric T. Han2, Thomas M. Link1, Sharmila Majumdar1, Roland Krug1

1Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, United States; 2Applied Science Laboratory, GE Healthcare, Menlo Park, CA, United States

There is some evidence that osteoporosis is associated with increased marrow fat content as well as an accelerated conversion from red marrow to yellow (fatty) marrow with age. In this work, we investigated the marrow fat composition in the proximal femur in vivo using IDEAL gradient echo imaging. 3-point IDEAL FGRE hip images of six healthy subjects were acquired and water-fat separation was performed using multi-peak IDEAL. The average fat fraction and standard deviation were determined in three different regions of interest (femoral head, greater trochanter and neck). Significant differences in marrow fat content were identified between the three regions for all subjects.

792. 1H MRS to Detect Biochemical Degenaration of the Vertebral Bone Marrow in Gaucher Disease

Simona Ortori1, Michela Tosetti2, Marzio Perri3, Margherita Marchetti1, Gabriele Caproni1, Laura Biagi2, Mirco Cosottini4, Virna Zampa1, Giuliano Mariani3, Carlo Bartolozzi1

1Divisione di Radiologia Diagnostica ed Interventistica, Azienda Ospedaliera Universitaria Pisana, Pisa, Italy; 2MR Laboratory, Stella Maris Scientific Institute, Pisa, Italy; 3Divisione di Medicina Nucleare, Azienda Ospedaliera Universitaria Pisana, Pisa, Italy; 4Dipartimento di Neuroscienze, Università di Pisa, Pisa, Italy

Gaucher disease is the most prevalent inherited, lysosomial storage disease and results in a deficient level of activity of β-glucocerebrosidase, a membrane-bound lysosomal enzyme. This deficiency leads to accumulation of the lipid glucocerebroside in the lysosomes of monocytes and macrophages, called Gaucher cells. The symptoms and pathology of Gaucher disease result from the accumulation of Gaucher cells in various organ system, including vertebral bodies. To evaluate the biochemical process underlying the infiltration of Gaucher cells, 1H-MRS has been acquired on vertebral bone marrow in patients affected by Gaucher disease, highlighting a significant reduction of fat content of any age range

793. Characterization of Trabecular Orientation in Chicken Femur by Multi-Directional SPENT (Sub-Pixel Enhancement of Non-Uniform Tissue)

Bailiang Chen1, Bernard Siow2, David Carmichael1,3, Freddy Odille2, Roger Ordidge1, Andrew Todd-Pokropek1

1Medical Physics and Bioengineering, University College London, London, United Kingdom; 2Centre for Medical Image Computing, University College London, London, United Kingdom; 3Institute of Neurology , University College London, London, United Kingdom

The recently proposed SPENT sequence can provide direction specific information based on the sub-voxel structural uniformity of a sample. Analogous to diffusion tensor imaging, given a voxel with a local anisotropic structure (e.g. trabecular bone), it is possible to characterize the orientation of sub-pixel micro-structure by applying SPENT with multiple directions. A 6-direction SPENT series was applied to a chicken femur head in order to characterize its trabecular bone orientation by reconstructing a 2D tensor in each voxel. Both tensor statistics and eigensystems were computed and showed good qualitative agreement with data from a subsequent micro-CT acquisitions.

794. The Effect of Freezing on Measurements of Trabecular Bone Structure Based on NMR Spectroscopy

Viktoria Prantner1, Hanna Isaksson1, Johanna Närväinen2, Eveliina Lammentausta3, Olli HJ Gröhn2,4, Jukka S. Jurvelin1

1Department of Physics, University of Kuopio, Kuopio, Finland; 2A.I. Virtanen Institute for Molecular Sciences, University of Kuopio, Kuopio, Finland; 3Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland; 4Biomedical Imaging Unit, University of Kuopio, Kuopio, Finland

NMR is a potential tool for the assessment of trabecular bone structure. Since trabecular bone provides a negligible NMR signal, the indirect evaluation of the trabecular bone structure is based on the analysis of water and fat components in the bone marrow. Earlier studies have revealed that freezing affects the bone marrow structure, suggesting there may be changes in the molecular structure. The aim of the current study is to investigate the effect of freezing on trabecular bone and bone marrow, as assessed by NMR spectroscopy.

795. Performance of Two Spin-Echo Sequences for Quantitative Structure Analysis of Trabecular Bone

Michael Jeffrey Wald1, Jeremy Francis Magland1, X. Edward Guo2, Felix Werner Wehrli1

1Laboratory for Structural NMR Imaging, University of Pennsylvania Medical Center, Philadelphia, PA, United States; 2Bone Bioengineering Laboratory, Columbia University, New York, United States

The performance of two spin-echo based pulse sequences for imaging trabecular bone microstructure are evaluated at 1.5T in seven fixed, cadaveric distal tibia specimens. SNR efficiency and sensitivity of image-derived trabecular bone structural parameters to variations in bone quality as assessed by µCT were investigated. Inter- pulse sequence correlations suggest similar structural sensitivity, while comparisons to µCT reveal good sensitivity but large deviations in absolute values between modalities.

796. Ultra-Short TE (UTE) Imaging of Skull and a Quantitative Comparison of Skull Images Obtained from MRI and CT

Liya Wang1, Xiaodong Zhong2, Longjiang Zhang3, Diana Tiwari1, Hui Mao1

1Department of Radiology and Emory Center for Systems Imaging, Emory University School of Medicine, Atlanta, GA, United States; 2MR R&D Collaborations, Siemens healthcare, Atlanta, GA, United States; 3Department of Radiology, Jinlin Hospital and Nanjing University College of Clinical Medicine, Nanjing, Jiangsu, China

This study provided a quantitative evaluation of skull images obtained using UTE MRI and a direct comparison to those from CT. The skull thickness measured from UTE images showed good agreement with those obtained from CT images in different slices. There is also a good correlation between the thickness measurements obtained from CT and UTE images. Signal intensity based evaluation showed that there is no statistical difference between UTE and CT images in outer, inner layer and diploe of the skull. The comparison of bone UTE MRI and CT of skull suggests that UTE images match closely with CT images.

797. MR Imaging Detects Impaired Angiogenesis and Trabecular Bone Formation During Endochondral Bone Growth Mediated Through PKBalpha/Akt1 in Gene Dosage Dependent Manner

Katrien Vandoorne1, Jeremy Magland2, Vicki Plaks1, Inbal E. Biton3, Amnon Sharir4,5, Elazar Zelzer4, Felix Wehrli6, Brian A. Hemmings7, Alon Harmelin3, Michal Neeman1

1Biological Regulation, Weizmann Institute, Rehovot, Israel; 2Department of Radiology, University of Pennsylvania Health System, Philadelphia, PA, United States; 3Veterinary Resources, Weizmann Institute, Rehovot, Israel; 4Molecular Genetics, Weizmann Institute, Rehovot, Israel; 5The Laboratory of Musculoskeletal Biomechanics and Applied Anatomy, Koret School of Veterinary Medi, Hebrew University of Jerusalem, Rehovot, Israel; 6Department of Radiology, University of Pennsylvania Health System, Philadelphia, PA, Israel; 7Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland

Since infiltration of the newly formed blood vessels is required for endochondral bone formation, and PKBalpha/Akt1 mediates intracellular signaling of angiogenesis, we postulated that a vascular deficiency at the site of the long bones could contribute indirectly to impaired bone development in PKBalpha/Akt1 deficient mice. Our study demonstrated using macromolecular DCE-MRI in vivo and ex vivo µCT and µMRI, vascular and bone developmental defects in PKBalpha/Akt1 null mice, and remarkably also in heterozygous mice, lacking a single copy of the gene.

798. Water and Fat Suppressed Proton Projection MRI (WASPI) Study on Bone Specimens After Proton-Deuteron Exchange

Haihui Cao1,2, Jerome L. Ackerman, 2,3, Guangping Dai, 2,3, Mirko Hrovat4, Melvin J. Glimcher, 2,5, Yaotang Wu, 2,5

1Department of Orthopedic Surgery, Children's Hospital , Boston, MA, United States; 2Harvard Medical School, Boston, MA, United States; 3Department of Radiology, Massachusetts General Hospital, Boston, MA, United States; 4Mirtech, Inc, Brockton, MA, United States; 5Department of Orthopedic Surgery, Children's Hospital, Boston, MA, United States

Questions have arisen as to the nature of the molecular species giving rise to the short-T2 proton signal in Water- and fat-suppressed proton projection MRI (WASPI), a noninvasive means to image bone. In this study we use deuterium exchange to identify the source of proton signal in WASPI.

799. Quantification of Bound and Mobile Water in Human Cortical Bone by 1H and 2H Magnetic Resonance

Henry H. Ong1, Alexander C. Wright1, Felix W. Wehrli1

1Laboratory for Structural NMR Imaging, Department of Radiology, University of Pennsylvania School of Medicine, Philadelphia, PA, United States

Magnetic resonance is a powerful tool for non-destructive study of bone water, which can provide insight into bone micro- and nanostructure. However, the MR signal of bone is comprised of several proton populations including collagen-associated water, and water within the pore space (Haversian and lacuno-canalicular system). We hypothesize that water in pores is predominantly free and water in the bone matrix is predominantly associated with collagen. Using 2H exchange and inversion recovery experiments, we estimated porosity in human cortical bone and found it to agree with micro-CT based volumetric measurements with a significant fraction being collagen-associated.

800. MR Spin Behavior During RF Pulses: T2 Vs. T2' Relaxation

Michael Carl1, Nikolaus Szeverenyi2, Mark Bydder2, Eric Han1, Graeme Bydder2

1GE Healthcare, Waukesha, WI, United States; 2University of California, San Diego

We investigated the behavior of the MR magnetization vector during RF pulses in the presence of rapid transverse relaxation caused by either amplitude loss or spin dephasing. We found that different tissues with the same T2* may generate different responses to RF pulses, dependent on whether the relaxation is dominated by a homogeneously or inhomogeneously broadened linewidth and RF optimization may hence require explicit knowledge of the intrinsic T2 and T2* of the tissue.

801. Multi-Modality Imaging of Bone Marrow Edema-Like Lesions and Associated Cartilage in Osteoarthritic Patients

Daniel Kuo1, Joseph Schooler1, Janet Goldenstein1, Sarmad Siddiqui1, Swetha Shanbhag1, Jean-Baptiste Pialat1, Andrew Burghardt1, Sharmila Majumdar1, Michael Ries2, Galateia Kazakia1, Xiaojuan Li1

1Musculoskeletal Quantitative Imaging Research (MQIR), Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, United States; 2Department of Orthopaedic Surgery, University of California, San Francisco, San Francisco, CA, United States

Osteoarthritis (OA) is a complex disease that affects both cartilage and bone. Bone marrow edema-like lesions (BMEL) are important in studying OA, but knowledge about them is limited. In this study, we take a multi-modality imaging approach, examining MR T1ñ and T2 values of BMEL-associated cartilage plus structure and composition of BMEL tissue using high resolution peripheral quantitative computed tomography (HR-pQCT) imaging and Fourier transform infrared (FTIR) spectroscopy. Our results indicate that regions of BMEL are associated with more advanced cartilage degeneration and that there is a localized imbalance in bone formation and mineralization specific to BMEL regions.

802. Perfusion Abnormalities of Bone Marrow Edema-Like Lesions in Knees with Anterior Cruciate Ligament Injury Using Dynamic Contrast-Enhanced MRI

Jin Zuo1, Sharmila Majumdar1, Xiaojuan Li1

1Radiology and Biomedical Imaging, Univ. of California, San Francisco, San Francisco, CA, United States

Anterior cruciate ligament (ACL) tear is a common knee injury, and is a risk factor of post-traumatic osteoarthritis (OA). The disease is frequently associated with bone marrow edema-like (BMEL) lesions which exhibit as an area of high signal intensity in T2-weighted, fat-saturated fast spin echo MR images. BMEL is also commonly seen in OA and has been associated with disease progression and pain in OA. However, the knowledge on the pathophyisiology and significance of BMEL in ACL-injured knees is very limited. Dynamic contrast enhanced MRI (DCE-MRI) can probe bone marrow and subchondral bone perfusion as well as fluid dynamics. Impaired perfusion in bone may lead to cartilage degeneration. A recent study showed bone marrow abnormalities were associated with BME in OA. The aim of this study is to apply DCE MRI to evaluate bone marrow perfusion in patients with ACL tears, and to compare the perfusion patterns between BMEL region and normal appearing bone marrow region.

803. The Influence of Running on Patellar Water Content and Bone Marrow Edema in Females with and Without Patellofemoral Pain

Kai-Yu Ho1, Houchun H. Hu2, Krishna S. Nayak2, Patrick M. Colletti3, Christopher M. Powers1

1Division of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, CA, United States; 2Department of Electrical Engineering, University of Southern California, Los Angeles, CA, United States; 3Department of Radiology, University of Southern California, Los Angeles, CA, United States

The purpose of this study was to investigate the influence of running on patellar water content and bone marrow edema (BME) in individuals with and without patellofemoral pain (PFP). Using the IDEAL protocol, two subjects with PFP and 2 pain-free controls were evaluated. Each subject underwent a pre-running MR scan, a 40-min moderate effort running, and a post-running MR scan. Our data showed that in persons with PFP, content and volume of local BME increases post-running. Additionally, the PFP subjects demonstrated increased water content of the bone marrow region post-running while the controls showed no changes in water content.

804. Using 18F NaF PET/CT to Image Increased Bone Activity in Patellofemoral Pain: Correlation with MRI

Christine Elizabeth Draper1, Michael Fredericson1, Thor F. Besier1, Gary S. Beaupre2, Scott L. Delp1, Andrew Quon1, Garry E. Gold1

1Stanford University, Stanford, CA, United States; 2VA Palo Alto Health Care System, Palo Alto, CA, United States

Articular cartilage deterioration is associated with the development of osteoarthritis. Cartilage health depends upon the integrity of the underlying subchondral bone and there may be abnormalities in bone metabolic activity that accompany structural defects in bone and cartilage. 18F NaF PET/CT enables bone metabolic activity to be visualized. We compared metabolic abnormalities detected using PET/CT with structural defects seen using MRI. We found that regions of increased bone metabolic activity do not always correlate with cartilage damage or bone marrow edema, indicating that 18F NaF PET/CT may image bone abnormalities prior to the development of structural damage seen using MRI.

805. Improved Fat-Suppression for Unspoiled GRASS Imaging of the Knee Using Multi-Peak IDEAL Chemical Shift Fat-Water Separation

Richard Kijowski1, Catherine Debra Hines2, Huanzhou Yu3, Scott Brian Reeder1,2

1Radiology, University of Wisconsin, Madison, WI, United States; 2Medical Physics, University of Wisconsin, Madison, WI, United States; 3GE Healthcare, Applied Science Laboratory, Menlo Park, CA, United States

This study was performed to demonstrate improvements in the quality of fat-suppression for unspoiled GRASS imaging of the knee using multi-peak fat spectral modeling and IDEAL fat-water separation. An IDEAL-GRASS sequence was performed at 3.0T on the knees of 10 asymptomatic volunteers. The IDEAL-GRASS images were reconstructed using a single-peak method and a multi-peak method that more accurately models the NMR spectrum of fat. Multi-peak IDEAL-GRASS had significantly greater (ppre contrast, however detailed ROI analysis shows differences in sub-auditory areas.

1180. Functional Imaging of Observation of Action in Elite Archers Using Video of Western-Style Archery Task

Hui-jin Song1, Joo-hyun Kim1, Jeehye Seo1, Moon-jung Hwang2, Young-ju Lee2, Kyung Jin Suh3, Sung Woo Kim3, Young Hwan Lee4, Dong Soo Yoo5, Yongmin Chang1,6

1Medical & Biological Engineering, Kyungpook National University, Daegu, Korea, Republic of; 2GE healthcare, Seoul; 3Dongguk University, Gyungju; 4Radiology, College of Medicine, Catholic University, Daegu; 5Radiology, College of Medicine, Dankook University, Chunan; 6Diagnostic Radiology, Kyungpook National University, Daegu, Korea, Republic of

Although the mirror neuron system has been extensively studied, no functional imaging data are currently available to gain insight in the possible difference of the mirror system between experts and novices. Therefore, the aim of the present study is to investigate the differences of activation in the mirror neuron system during viewing tool use familiar to experts between expert archers and novice subjects. Our results demonstrated that expert archers showed strong activation in the mirror neuron system during viewing videos of Western-style archery relative to inexpert control subjects. Taken together, our data consistent with previous reports suggest that human mirror neuron system could contain representations of tool use and expand motor repertoire with tool use experiences.

1181. Localization of the Hand Motor Area Using BOLD and ASL FMRI

Marco Pimentel1, Pedro Vilela2, Inês Sousa3,4, Patricia Figueiredo3

1Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Lisbon, Portugal; 2Imaging Department, Hospital da Luz, Lisbon, Portugal; 3Instituto Superior Técnico, Lisbon, Portugal; 4Healthcare Sector, Siemens, S.A., Portugal

Previous studies have shown that ASL-based fMRI exhibits better spatial specificity than the most commonly used BOLD contrast. Here, we compared the localization of the hand motor area obtained by simultaneous ASL-BOLD fMRI and standard BOLD fMRI at 3T with well established anatomical landmarks, in a group of 15 healthy subjects. Our results indicate that the localization of the hand motor area obtained using ASL fMRI is significantly less variable and closer to the hand motor cortex anatomical landmarks than the one produced by BOLD fMRI. This supports the notion that ASL may more accurately localize brain activation than BOLD.

1182. Understanding Consciousness from Information and Integration Within the Thalamocortical System

Xiaolin Liu1, Jingsheng Zhou2, Anthony G. Hudetz3, Shi-Jiang Li1

1Biophysics, Medical College of Wisconsin, Milwaukee, WI, United States; 2Rehabilitation Department, Xuanwu Hospital Capital Medical University, Beijing, China; 3Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, United States

Understanding the neural mechanisms of consciousness requires identification of the nature of contributions from each of the potential neural correlates, which together generate a complete cognitive experience. We examined the specific and nonspecific thalamic connections in the brain based on the neuroanatomical findings implicating their respective functional roles in sustaining information and integration, which are essential to consciousness. Our results endorse the view that the thalamocortical system is essential to consciousness, and support the hypothesis that the nonspecific thalamic connections largely reflect brain regions that are responsible for information integration, potentially sustaining various awareness functions.

1183. Examining Structure and Function in a Cognitive Task

Jeffrey Thomas Duda1, Corey McMillan, Murray Grossman, James Gee

1Bioengineering, University of Pennsylvania, Philadelphia, PA, United States

Structure and function are examined in the language network with DT-MRI and BOLD fMRI during a cognitive task. Activated cortical regions are identified and used to determine activation levels in each subject. Additionally, the regions are used to identify fiber tracts of interest. Canonical correlation analysis is used to identify correlations between functional activation and average fractional anisotropy in the fiber tracts. For each correlation found, the highest weightings are found for cortical regions and a tract that connects to that region.

1184. Effects of FMRI Acoustic Scanner Noise on Neural Processing Networks During Task Performance and Rest

Dave Langers1, Pim van Dijk1

1Otorhinolaryngology, University Medical Center Groningen, Groningen, Netherlands

Scanner acoustic noise may detrimentally affect stimulus/task-evoked neural responses in fMRI. This has been reported for the unimodal and associative auditory systems, but also for the default mode network and other brain systems.

In the current experiment, the effects of scanner noise in resting state fMRI are studied. We find that similar independent components may be extracted with and without background scanner noise, both during active and resting states. However, the overall strength, spatial extent, and temporal dynamics of various neural components are affected by the presence of background noise. Our results both corroborate and extend previous findings in literature. More detailed specific findings for various brain systems will be presented.

1185. Neural Correlates of Feigned Hearing

Bradley McPherson1, Wayne Wilson2, David Copland3,4, Katie McMahon5

1Division of Speech and Hearing Sciences, Hong Kong University, China; 2Division of Audiology, University of Queensland, Australia; 3Centre for Clinical Research, University of Queensland, Australia; 4School of Health and Rehabilitation Sciences, University of Queensland, Australia; 5Centre for Magnetic Resonance, University of Queensland, Brisbane, Queensland, Australia

Can we use patterns of brain activity to detect when someone is feigning a hearing loss? To answer this question, we asked 15 adult participants to respond to pure tones and simple words correctly, incorrectly, randomly, or with the intent to feign a hearing loss.

1186. An FMRI Study of Memory Performance in Type 2 Diabetes Mellitus: A Twin Study

Amanda Wood1, Jian Chen2,3, Thanh G. Phan2, Kimberlea Cooper2, Stacey Litras2, Srikanth Velandai2

1Developmental and Functional Brain Imaging,Critical Care and Neuroscience, Murdoch Childrens Research Institute, Melbourne, VIC, Australia; 2Stroke and Ageing Research Group, Department of Medicine, Monash University, Melbourne, VIC, Australia; 3Developmental and Functional Brain Imaging,Critical Care and Neuroscience , Murdoch Childrens Research Institute, Melbourne, VIC, Australia

Type 2 Diabetes mellitus (DM) is linked to a greater risk of dementia, but the underlying mechanisms and brain regions involved are unknown. We conducted a co-twin (DM/non DM) case-control study of fMRI activation during a visual memory task. Non DM twins showed greater activation of temporal, parietal and occipital cortices suggesting involvement of these areas in DM pathology.

Animal fMRI

Hall B Wednesday 13:30-15:30

1187. Increased Sensitivity to the BOLD-FMRI Signal Response During Electrical Forepaw Stimulation in Mice Using a Cryogenic RF Probe

Christof Baltes*1, Simone Bosshard*1, Thomas Mueggler1,2, Markus Rudin1,3

1Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland; 2Pharmaceutical Research Neuroscience, F. Hoffmann-La Roche Ltd., Basel, Switzerland; 3Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland

BOLD-fMRI in mice using electrical forepaw stimulation was performed with a cryogenic transceive RF probe and a room-temperature receive-only surface coil. The effect of the increased sensitivity of the cryogenic probe on detecting BOLD responses was analyzed. In fMRI experiments, a gain in image SNR and in temporal SNR of a factor of 3.10 and 1.77 was found, respectively. As further optimization parameter adjusting the thermal shield temperature of the cryogenic probe allows for altering baseline perfusion and accordingly BOLD responses. Cryogenic cooling reduces BOLD signal variations by a factor of 1.59 and therefore increases the statistical power of fMRI.

1188. Investigating Color Vision Using FMRI: Rodent Vs Primate

Andy Paul Salzwedel1, Matt Mauck2, James Kuchenbecker3, Chris Pawela1, James Hyde1, Maureen Neitz3, Jay Neitz3

1Biophysics, Medical College of Wisconsin, Milwaukee, WI, United States; 2Department of Ophthalmology, Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, WI, United States; 3Ophthalmology, University of Washington, Seattle, WA, United States

In a comparative study, the visual pathways of two different animal models (rodent vs primate) were probed using high field strength (9.4T) fMRI. The primary goal of this research was to assay the color vision systems of these two species in hope of demonstrating the evolutionary homology thereof. Here we present several techniques that combine to form a unique overall method for probing this pathway; pharmacological intervention (AP4), precession fMRI compatible LED based stimuli, and intra-brain controls.

1189. Detectability of the BOLD Signal

Jozien Goense1, Hellmut Merkle2, Nikos Logothetis1,3

1Department of Physiology of Cognitive Processes, Max-Planck Institute for Biological Cybernetics, Tuebingen, Germany; 2Laboratory of Functional and Molecular Imaging, NINDS, NIH, Bethesda, MD, United States; 3Division of Imaging Science and Biomedical Engineering, University of Manchester, Manchester, United Kingdom

The BOLD signal is a weak signal, and hence if no BOLD signal is found in an area this does not necessarily mean there is no neural activity in that area. Signal dropout, artifacts, instability, physiological noise, RF-coil inhomogeneity etc. can all reduce the SNR locally leading to decreased detectability of the BOLD signal Here we illustrate that calculation of the spatial distribution of the detection for a given set of experimental conditions allows us to estimate the confidence by which absence of an fMRI signal can be interpreted as an absence of neural activity.

1190. BOLD FMRI of Anesthetized Baboons

Hsiao-Ying Wey1,2, Jinqi Li1, M. Michelle Leland3, Lisa Jones3, C Akos Szabo4, John W. Roby1, James T. Scribner1,2, Ghzawan M. Kroma2, Peter T. Fox1, Timothy Q. Duong1,2

1Research Imaging Institute, UT Health Science Center at San Antonio, San Antonio, TX, United States; 2Radiology, UT Health Science Center at San Antonio, San Antonio, TX, United States; 3Laboratory Animal Resources, UT Health Science Center at San Antonio, San Antonio, TX, United States; 4Neurology, UT Health Science Center at San Antonio, San Antonio, TX, United States

This study reports a robust anesthetized baboon model for BOLD fMRI studies on a clinical 3T human MRI scanner. BOLD fMRI of visual and somatosensory/motor stimulations in anesthetized baboons were investigated. Comparisons of BOLD fMRI sensitivity were made between isoflurane and ketamine anesthetics with and without paralytics. To our knowledge, this is the first report on baboon BOLD fMRI of visual and somatosensory/motor.

1191. Using T1 Map to Guide Functional MRI Study of Ipsilateral Somatosensory Cortex in Awake Non-Human Primates

Junjie V. Liu1, Nicholas A. Bock2, Ara Kocharyan1, Julie Mackel1, Afonso C. Silva1

1NINDS, National Institutes of Health, Bethesda, MD, United States; 2Medical Physics, McMaster University, Hamilton, ON, Canada

By combining BOLD fMRI with T1 mapping, here we study the ipsilateral responses in somatosensory cortex of awake marmosets. Our results show a surprising spatial mismatch between contralateral and ipsilateral representations of the same body part.

1192. Fine -Scale Functional Connectivity Network Revealed at High Field (9.4T) Within Somatosensory Cortices of Anesthetized New World Monkeys

Arabinda Mishra1, Baxter P. Rogers1, Barbara Dillenburger1, Kevin Wilson1, Feng Wang1, John C. Gore1, Li Min Chen1

1Radiology & Radiological Science, VUIIS, Nashville, TN, United States

Correlations between resting state BOLD signals in widely distributed brain regions is a key signature of consciously driven mental activity in humans. In this work we attempted to explore if a fine scale functional connectivity can be detected within the anatomically well defined primary somatosensory cortex (SI) at high field and whether the functional connectivity reflects anatomical hierarchical relationships in anesthetized monkeys. We found that functional connectivity exists among anatomically interconnected cortical subregions (areas 3a, 3b, 1 and 2) within SI without the involvement of consciousness (or alertness), and the strengths of the correlation among these subregions reflect the strength of their underlying anatomical connections.

1193. fMRI Analysis of the Olfactory Responses to Home-Stream Water in Sockeye Salmon

Hiroshi Bandoh1, Ikuhiro Kida2, Hiroshi Ueda1,3

1Division of Environmental Science Development, Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido, Japan; 2Integrated Neuroscience Research Team, Tokyo Institute of Pschiatry, Setagaya-ku, Tokyo, Japan; 3Laboratory of Aquatic Ecosystem Conservation, Field Science Center for Northern Biosphere, Hokkaido University, Sapporo, Hokkaido, Japan

The odor-information processing involved in olfactory imprinting and homing of the home-stream odor in the central nervous system of salmon has not been completely elucidated. In this study, to investigate this information-processing mechanism, we used BOLD fMRI to measure the response to home-stream water in the olfactory bulb and telencephalon of sockeye salmon. The presence of BOLD signals in the dorsal area of the telencephalon indicated that the odor information for home-stream water was processed in a specific area in the telencephalon of sockeye salmon.

1194. Evaluation of Functional Deficit and Recovery in the Rat Somatosensory Cortex After Moderate Traumatic Brain Injury Using FMRI

Juha-Pekka Niskanen1,2, Antti Airaksinen1, Jari Nissinen1, Asla Pitkänen1, Olli Gröhn1

1Department of Neurobiology, A. I. Virtanen Institute for Molecular Sciences, University of Kuopio, Kuopio, Finland; 2Department of Physics, University of Kuopio, Kuopio, Finland

Traumatic brain injury (TBI) is a major cause of death and disability worldwide. In this study, 10 rats with TBI and 6 sham operated controls were imaged during electrical stimulation of the forepaws before TBI and 1, 2 and 8 weeks after TBI. fMRI with forepaw stimulation was able to reveal functional deficit after TBI in the somatosensory cortex outside of the main lesion and also detect partial sensory recovery 8 weeks after TBI. The results suggest that fMRI could serve as a non-invasive user independent tool to evaluate functional recovery after TBI.

1195. Complexity in the Spatiotemporal Hemodynamic Response to Sensory Stimulation in the Un-Anesthetized Rat

Christopher James Martin1, Jason Berwick2, Ying Zheng2, John Mayhew2

1Radiation Oncology and Biology, University of Oxford, Oxford, Oxfordshire, United Kingdom; 2University of Sheffield

The aim of this work was to investigate the spatiotemporal changes in hemodynamics that underlie fMRI signal changes in response to stimulus evoked changes in neuronal activity. We used optical imaging spectroscopy in an un-anesthetized rat model, to provide measures of changes in blood volume and oxygenation at higher spatial and temporal resolution than possible with fMRI, without the potentially confounding effects of anesthesia. We found a complex spatiotemporal hemodynamic response function, consisting of both increases and decreases in blood volume and oxygenation as well as oscillatory response components. We discuss the implications of these findings for fMRI.

1196. BOLD Changes in Somatosensory Cortex of Malnourished Rats

R Martin1, R Godinez1, Alfredo O. Rodriguez1

1Departament of Electrical Engineering, Universidad Autonoma Metropolitana Iztapalapa, Mexico, DF, Mexico

Malnutrition is a main public health problem in developing countries. Incidence is increasing and the mortality rate is still high. Functional Magnetic Resonance Imaging (BOLD) was used for mapping brain activity of malnourished rats. The food competition method was applied to a rat model to provoke malnutrition during lactation. The vibrissae-barrel axis was also used due to its advantages for studying structure, function, development and plasticity within the somatosensory cortex. BOLD response changes caused by the trigeminal nerve stimulation on brain activity of malnourished and control rats were obtained at 7T. Results showed a major neuronal activity in malnourished rats.

1197. Temporal Hemodynamic Responses of BOLD FMRI in the Rat Brain Related to Electric Forepaw Stimulation

Dewen Yang1, Zhiyong Xie1, James Goodman1, Anne Burkholder2, Nancy Poy2

1BioImaging COE, Pifizer Global Research & Development, Groton, CT, United States; 2WW Comparative Medicine, Pifizer Global Research & Development, Groton, CT, United States

The neurovascular response to electric forepaw stimulation (EFS) was observed with BOLD signal in the contralateral somatosensory cortex in 11 rats with normal blood gas physiology under alpha-chloralose anesthesia. Serial CBF maps were also acquired during EFS in a subset of these rats. BOLD activation and CBF maps showed elevated blood flow in the contralateral somatosensory cortex at the time of stimulation, after which the regional activation and increases in CBF spread to cortex in the ipsilateral hemisphere.

1198. Reduced BOLD Response in Mice Lacking Nociceptor Specific Sodium Channels (Nav1.7) Indicates Altered Pain Processing

Simone Claudia Bosshard1, Christof Baltes1, Markus Rudin1,2

1Institute for Biomedical Engineering, ETH Zürich, Zurich, Switzerland; 2Institute of Pharmacology and Toxicology, University of Zurich, Zurich, 8057, Switzerland

Electrical stimulation of the forepaws is a widely used stimulation paradigm in functional magnetic resonance imaging (fMRI). We used transgenic mice lacking the voltage-gated sodium channel Nav 1.7 specifically at the nociceptors (Nav1.7R-/-) to study altered pain sensitivity. Nav1.7R-/-, WT littermates and WT animals of our lab were examined using BOLD fMRI. The detected BOLD signal changes of the Nav1.7R-/- animals were significantly reduced as compared to the two WT groups. This is in line with behavioral data reported for these mice. This proves our method to be a valuable tool to non-invasively study pain processing in mice.

1199. BOLD Response and Associated Metabolic Changes in the Rat Barrel Cortex Following Sustained Trigeminal Nerve Stimulation

Nathalie Just1,2, Hanne Frenkel3, Rolf Gruetter3,4

1LIFMET, CIBM, EPFL, Lausanne, Switzerland; 2Department of Radiology, UNIL, Lausanne, Switzerland; 3LIFMET, EPFL, Lausanne, Switzerland; 4Department of Radiology, UNIL and HUG, Lausanne and Geneva, Switzerland

The present study examined the BOLD fMRI response of the rat barrel cortex upon sustained trigeminal nerve stimulation. Moreover, the alterations in the barrel cortex metabolite concentration due to prolonged functional activation were measured using 1H-MRS at 9.4T. The results demonstrate that sustained BOLD responses can be obtained reproducibly in the rat barrel cortex following prolonged trigeminal nerve stimulation. Furthermore, preliminary functional MRS (fMRS) results show changes in several metabolites in the barrel cortex and in particular an increase in lactate levels during barrel cortex activation.

1200. The Utility of FMRI in Measuring Brain Plasticity Following Peripheral Nerve Injury

Christopher Paul Pawela1,2, Bharat B. Biswal3, Rupeng Li2, Anthony G. Hudetz4, Hani S. Matloub1, James S. Hyde2

1Department of Plastic Surgery, Medical College of Wisconsin, Milwaukee, WI, United States; 2Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, United States; 3Department of Radiology, University of Medicine and Dentistry of New Jersey, Newark, NJ, United States; 4Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, United States

In this study brain reorganization following nerve injury and repair was followed for a twelve week period with BOLD fMRI in a rat model. Primary sensory functional return progressed over the entire study period whereas thalamic areas did not functionally return until the twelve week time point. This study demonstrates the utility of using BOLD fMRI as a substitute for conventional electrophysiology in studies of brain plasticity and has many applications outside of peripheral nerve injury and repair.

1201. Investigating the Role of Transcallosal Projections in Mediating Neuroplasticity Following Injury in a Rat Using FMRI

Jennifer I. Wood1,2, Suresh E. Joel1,3, Michael T. McMahon1,2, James J. Pekar1,2, Galit Pelled, 2,4

1F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States; 2The Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, United States; 3The Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, United States; 4F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute , Baltimore, MD, United States

Human and animal studies suggest the involvement of the transcallosal projection in shaping neuroplasticity following injury may be crucial in dictating the rehabilitation probability. This study was designed to investigate the role of the transcallosal pathways in mediating neuroplasticity following injury in a rat model of sensory deprivation. Using fMRI, we have studied the time course and the age-dependency of which the transcallosal projections effect cortical reorganization. The results demonstrate that the transcallosal projections involvement in neuroplasticity varies dependent on the age and the time following the injury and may introduce a critical consideration when choosing the right rehabilitation strategy.

1202. BOLD FMRI Assessment of the Functional Response to Taste Stimulation in Rat Brain

Ikuhiro Kida1, Yoko Hoshi1, Yoshinobu Iguchi1

1Integrated Neuroscience Research Team, Tokyo Institute of Pschiatry, Setagaya-ku, Tokyo, Japan

Some aspects of taste information processing have not been conclusively clarified, such as the process by which the gustatory cortex uses spatial codes to characterize taste information.We used BOLD fMRI measurements obtained at 7 T in an animal system to investigate the process by which taste information is encoded. Sucrose yielded a reproducible BOLD signal increase in the gustatory cortex. During taste stimulation, BOLD signals were also detected in the lip region of the primary somatosensory cortex, secondary somatosensory cortex, and amygdalae. This is the first study that used BOLD fMRI to observe gustatory activation in the rat brain.

1203. Functional MRI of Cortico-Striato-Thalamal Circuit Using a Novel Flexible Polyimide-Based Microelectrode Array Implanted in Rodent Deep Brain

Pai-Feng Yang1, You-Yin Chen2, Jyh-Horng Chen1, Chen-Tung Yen3

1Electrical Engineering, National Taiwan University, Taipei, Taiwan; 2Electrical Engineering, National Chiao-Tung University, Hsinchu, Taiwan; 3Zoology, National Taiwan University, Taipei, Taiwan

This paper proposes a novel flexible MRI-compatible microelectrode array that leverages the stimulation and recording properties for neuroscience application. We perform functional MRI to investigate the cortico-striato-thalamal circuit with thalamic stimulation. Significant positive BOLD responses were observed in receptive field in upper lip region (S1ULp), barrel field (S1BF) and secondary somatosensory cortex (S2). Negative BOLD responses were revealed in caudate putamen (CPu). We inferred a limbic cortico-striatal loop might exist.

1204. A Non Invasive Experimental Protocol for FMRI Studies: Investigation of the Basal Ganglia-Cortex Circuit in a Rat Model

Salem Boussida1, Amidou Traore2, Jean-Pierre Renou2, Franck Durif3

1INRA, UR370 QuaPA/NMR plateforme, Centre Clermont-Ferrand/Theix, F-63122 Saint Genès Champanelle, France; 2INRA, UR370 QuaPA/NMR plateforme, Centre Clermont-Ferrand/Theix, F-63122 Saint Genès Champanelle, France; 3CHU Clermont-Ferrand, Service de Neurologie, Clermont-Ferrand, F-63001, France.

Combination of blood– oxygen level-dependent functional magnetic resonance imaging (BOLD fMRI) and electrical hindpaw stimulation has been used as a standard model to study the somatosensory pathway and brain rehabilitation in rats. In the present study, we examined the feasibility of performing BOLD fMRI experiments on rat to investigate the activity of the basal ganglia (BG)-cortex circuit associated to hindpaw sensitive stimulation. These findings will have relevance in the fMRI studies dealing with physiopathology of neurodegenerative diseases such as Parkinson

1205. Refining the Sensory and Motor Ratunculus of the Rodent Upper Extremity: Evaluation of the C7 Nerve Root Using FMRI and Direct Nerve Stimulation

Patrick C. Hettinger1, Rupeng Li2, Ji-Geng Yan1, Hani S. Matloub1, Young R. Cho1, Matthew L. Runquist2, Christopher P. Pawela1, James S. Hyde2

1Plastic Surgery, Medical College of Wisconsin, Milwaukee, WI, United States; 2Biophysics, Medical College of Wisconsin, Milwaukee, WI, United States

The purpose of this study is to further define the ratunculus by observing cortical activity using BOLD fMRI during direct stimulation of the C7 nerve root. In this study, 7 Sprague-Dawley rats underwent implantable electrode placement on the C7 nerve root. BOLD response to nerve stimulation was then studied using a Bruker 9.4T MRI scanner. C7 nerve stimulation resulted in a small amount of activation in the S1FL region along with a large amount of activation within the M1/M2 regions. These findings are similar to the sensory and motor distributions described in human C7 nerve root literature.

1206. Functional MRI Detects Chronically Enhanced Somatosensory Activation Maps Following Multiple Seizures in Rats.

Ursula I. Tuor1, Jennifer Vuong2, Jeffrey F. Dunn3, Tadeusz Foniok1, Dave Kirk4, Amy H. Henderson2, G Campbell Teskey2,5

1Institute for Biodiagnostics (West), National Research Council of Canada , Calgary, Alberta, Canada; 2Psychology, University of Calgary; 3Radiology, University of Calgary; 4Experimental Imaging Centre, University of Calgary; 5Anatomy and Cell Biology, University of Calgary, Calgary, Alberta, Canada

We used functional magnetic resonance imaging (fMRI) in rats to investigate whether following 20 repeatedly elicited seizures there are seizure-induced alterations in the somatosensory maps to forepaw stimulation. We observed increased areas of activation both acutely (1-3 days) and chronically (3-5 weeks) after experimental kindling induced epilepsy. The data indicate that there is considerable neuroplasticity and development of new pathways during the progression of epilepsy. Whether comparable plasticity of cortical maps is present in humans should be tested using fMRI in future studies, considering that such seizure-induced changes may be involved in producing interictal behavioural disturbances.

1207. Layer-Specific FMRI of Photic Stimulation in the Rat Retina at 11.7 T

Yen-Yu Ian Shih1, Bryan H. De La Garza1, William J. Lavery1, Eric R. Muir1,2, Timothy Q. Duong1

1Research Imaging Institute, Ophthalmology/Radiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States; 2Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, United States

The retina is about 276 micron thick including the choroid and has highly organized laminar structures. This study reports, for the first time, the feasibility of high-resolution blood-volume fMRI to image layer specific (retinal and choroidal) visual responses in the rat retina at 11.7T up to 40x40x600 micron nominal resolution. Given that the choroid is behind the retina and the retinal pigment epithelium, it is generally inaccessible by optical techniques. Blood-volume fMRI thus could provide a unique means to evaluate lamina-specific functional changes in the rat retina where many retinal disease models are readily available.

1208. Pass-Band Balanced Steady State Free Precession Functional MRI of the Mouse Retina

Eric Raymond Muir1,2, Sung-Hong Park3, Timothy Q. Duong2

1Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, United States; 2Research Imaging Institute, Ophthalmology/Radiology, UT Health Science Center San Antonio, San Antonio, TX, United States; 3Research Imaging Institute, Radiology, UT Health Science Center San Antonio, San Antonio, TX, United States

BOLD fMRI of the thin retina with the widely used EPI acquisition is challenging because the eye is a region of large magnetic inhomogeneity and high-resolution EPI is pushing the limits of gradient performance, resulting in susceptibility-induced signal drop out and image distortion. To overcome these limitations, we implemented a pass-band balanced steady state free precession (bSSFP) sequence for fMRI of the mouse retina at 45x45x500 µm. bSSFP has comparable temporal resolution and SNR per unit time as EPI, without the artifacts common in EPI. bSSFP fMRI could reliably detect layer-specific responses to hypoxic challenge in the mouse retina.

1209. Simultaneous FMRI and Long-Term in Vivo Electrochemistry (LIVE): Identifying the Neurochemical Correlates of Functional Imaging Signals

John Lowry1, Karen Griffin2, Stephen McHugh3, Nicola Sibson4

1Department of Chemistry, National University of Ireland, Maynooth, Ireland; 2University College Dublin, Ireland; 3Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom; 4Gray Institute for Radiation Oncology and Biology, University of Oxford, Oxford, Oxfordshire, United Kingdom

Long-term in-vivo electrochemistry (LIVE) enables real-time measurement of brain metabolites. Here we have simultaneously obtained BOLD fMRI and amperometric LIVE tissue oxygen data from rat cerebral cortex, during both increases and decreases in inspired oxygen. BOLD and tissue oxygen measurements demonstrated close correlation during both complete oxygen removal (negative responses) and increases in inspired oxygen (positive responses). Our findings demonstrate the feasibility of obtaining real-time metabolite information during fMRI acquisition. The results show that the BOLD signal provides a close correlate of the tissue oxygen dynamics or, alternatively, that tissue oxygen concentration can predict the magnitude of the BOLD response.

1210. Evaluation of Cerebral Energy Demand During Graded Hypercapnia

Stefan Alexandru Carp1, Maria Angela Franceschini1, David Alan Boas1, Young Ro Kim1

1Martinos Center/Radiology, Massachusetts General Hospital, Charlestown, MA, United States

The cerebral metabolic rate of oxygen (CMRO2) is a physiological parameter closely linked to neural activation as well as to various disease states. Hypercapnic calibration is used to calibrate the BOLD-CBF-CBV relationship under the assumption of iso-metabolic blood flow increase during CO2 inhalation. Simultaneous near infrared optical measurements of cerebral blood volume, blood flow and oxygen extraction can also be used to monitor CMRO2 changes, albeit at low spatial resolution. We use these optical measurements during graded hypercapnia to test the iso-metabolic assumption, and demonstrate an apparent increase in brain metabolism at higher inhaled CO2 levels.

1211. Dissociation of BOLD and Local Field Potentials

Wen-Ju Pan1, Matthew Magnuson1, Garth Thompson1, Waqas Majeed1, Dieter Jaeger2, Shella Keilholz1

1BME, Georgia Institute of Technology / Emory University, Atlanta, GA, United States; 2Biology, Emory University, Atlanta, GA, United States

To examine what extent consistence of the measurements between BOLD fMRI and local field potential (LFP), we evaluated BOLD and LFP simultaneously in rat somatosensory cortex with a combined measurement technique. The preliminary results indicated a dissociation between BOLD and LFP during low-level neural activity, which might mirror the limitation of neurovascular coupling, the bridge between BOLD and neural activity.

1212. TR and TE Dependence on Low Frequency BOLD Fluctuations

Matthew Evan Magnuson1, Wenju Pan1, Waqas Majeed1, Garth Thompson1, Shella Keilholz1

1Biomedical Engineering, Georgia Institute of Technology / Emory University, Atlanta, GA, United States

Low freqnecy fluctuations in resting state BOLD data have often been used to map functional connectivity in the rat brain. These low frequency BOLD fluctuations contain contributions from CBF, CBV, and CMRO2. Each of these components have unique physiological time signatures and effective echo times; therefore, modification of the TR and TE used in resting state scans should result in altered contributions from each BOLD component. In this study we examine the dependence of the selection of the TR and TE variables on low frequency resting state data.

1213. Further Test and Validation of Saturation-Recovery T1 MRI Measurement for Imaging Absolute CBF Change

Xiao Wang1, Xiao-hong Zhu1, Yi Zhang1, Wei Chen1

1Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, MN, United States

The feasibility of saturation-recovery T1 MRI for imaging and quantifying absolute CBF change was further tested at 9.4T using a rat hypercapnia model on two aspects: using diffusion gradients to investigate macrovascular inflow contribution; and slab saturation with varied thickness to test the effects of blood transit distance on measuring CBF. The results indicate that the outcomes of CBF changes induced by hypercapnia were coincident with the literature reports, and not significantly affected by large-vessel inflow effect and blood transit time. The overall results demonstrate that the saturation-recovery T1 MRI is sensitive to microvascular perfusion; it provides a noninvasive and reliable imaging approach for studying cerebral perfusion changes induced by physiology or pathology perturbation.

1214. In Vivo MR Measurement of Arterial Pulse Pressure in the Murine Aorta

Volker Herold1, Marco Parczyk1, Wolfgang Rudolf Bauer2, Eberhard Rommel1, Peter Michael Jakob1

1Department of Physics EP5, University of Wuerzburg, Wuerzburg, Bayern, Germany; 2Medizinische Universitätsklinik, University of Wuerzburg, Wuerzburg, Bayern, Germany

Mouse models are increasingly used to investigate functional and cardiovascular parameters. In this work we present an approach to noninvasively estimate the arterial pulse pressure by measuring the time dependant blood flow pulse and the local pulse wave velocity. By determining the complex impedance with solutions from the Navier-Stokes equations for incompressible fluids, the pressure pulse could be calculated from the accordant flow pulse. The present results are in good agreement with results from the literature obtained by invasive methods.

1215. Problems for Motion Correction: Paradigm Correlated Motion Remains a Confounding Source for FMRI Artefacts.

Lubos Budinsky1, Benito de Celis Alonso2, Marina Sergejeva1, Andreas Hess2

1Institute of Pharmacology, FAU, Erlangen, Germany; 2Institute of Pharmacology, FAU, Erlangen, Germany

The undesired motion, which is correlated with the fMRI paradigm (often present in experiments which are using mechanical stimulation or painful stimulus) can create false areas of an activity, which could remain real BOLD activity areas and a signal time course. Here we present series of fMRI experiment with phantoms and dead animals to which the motion was induced by using an air driven device integrated into the animal cradle. Using results from these experiments we suggest strategy, how to deal with this problem even if conventional motion correction algorithm are not able to remove these false areas completely.

1216. Functional MRI in the Rat at 9.4 T and 16.4 T

David Zsolt Balla1, Hannes M. Wiesner1, Gunamony Shajan1, Rolf Pohmann1

1High Field Magnetic Resonance Center, Max Planck Insitute for Biological Cybernetics, Tübingen, Baden-Württemberg, Germany

Functional MRI (fMRI) in animals at high magnetic fields keeps expanding our knowledge about the basics of neural processing but the specificity of the fMRI-signal is still under ongoing investigation. Yet, as the signal to noise ratio in MRI depends linearly on the magnetic field strength and calls for even stronger magnets for the detection of even smaller anatomical details, the relation between the functional MR-response and field strength can only be approximated with complex models. In this study the blood oxygenation dependent (BOLD) effect was measured and compared at 9.4 T and 16.4 T in the same animal with segmented gradient-echo (GE) and spin-echo (SE) echo planar imaging (EPI) sequence using optimal echo times for the respective field. Furthermore, high resolution fMRI acquisition at 16.4 T was performed up to a 50 µm in-plane accuracy and for an 8 s temporal resolution without the use of cryo-coils or coil-arrays.

1217. BOLD, CBV, and CBF FMRI of Caudate Putamen in Rat Brain During Noxious Electrical Stimulation: Its Negative Hemodynamic Response to Neural Activities

Fuqiang Zhao1, Denise Welsh1, Mangay Williams1, Alexandre Coimbra1, Mark O. Urban2, Richard Hargreaves2, Jeffrey Evelhoch1, Donald S. Williams1

1Imaging Department, Merck Research Laboratories, West Point, PA, United States; 2Neuroscience Department, Merck Research Laboratories, West Point, PA, United States

In central nervous system, neuronal activity generally leads to increases in local venous blood oxygenation level (BOLD), cerebral blood flow (CBF), and cerebral blood volume (CBV). However, previous studies have reported that the neural activity in rat caudate putamen (CPu) during noxious electrical stimulation (NES) of paws causes BOLD and CBV decreases. To further understand the specific hemodynamic response in this anatomical structure and its temporal characteristics, BOLD, CBV, and CBF fMRI studies were performed in a rat brain slice containing the CPu. Our results suggest that the neural activity in the CPu during NES causes decreases in CBV and CBF, and an increase in CMRO2 which lasts >2 minutes after stopping the NES.

1218. fMRI at 17.6 T and Optical Fiber-Based Ca2+-Imaging in Rodents

Albrecht Stroh1, Florian Schmid2, Afra Wohlschlaeger3, Valentin Riedl4, Jenny Kressel3, Cornelius Faber2

1Department of Neuroradiology, Technical University Munich, Munich, Germany; 2Institute for Clinical Radiology, University Hospital Münster, Münster, Germany; 3Department of Neuroradiology, Technical University Munich, Germany; 4Department of Neurology, Technical University Munich, Germany

n this study we tested the feasibility of rat fMRI at highest field strength in combination with an implanted optical fiber. We aim for the combination of fiber based optical Ca2+ imaging with functional magnetic resonance imaging (fMRI) at 17.6 T in vivo. We increased the temporal resolution of fMRI to 20 ms by applying k-space segmentation. Additionally, we conducted fiber-based Ca2+ imaging in mice upon electric forepaw stimulation, detecting neuronal population activity. Our study indicates that a multimodal approach combining a global method like fMRI with a spatially confined, highly specific method as optical Ca2+ imaging becomes amenable.

1219. Layer Specific Detection of Inhibitory FMRI Response in Somatosensory Cortex Through Cortico-Cortical Interaction in Rats

Yoshiyuki Hirano1, Alan P. Koretsky2, Afonso C. Silva1

1CMU, LFMI, NINDS, NIH, Bethesda, MD, United States; 2FMMS, LFMI, NINDS, NIH, Bethesda, MD, United States

We investigated the laminar dependence of cortico-cortical interactions induced by paired bi-lateral somatosensory stimulation in α-chloralose anesthetized rats. When compared to the response obtained at 0 ms ISI, the BOLD percent signal change in the S1FL responding to the late stimulus was decreased by 47 % at 40 ms ISI. The degree of suppression in layers III to V was stronger than suppression of fMRI changes in layers I-II and in bottom of layer VI. Our data shows that BOLD fMRI has sufficient spatial and temporal resolution to study cortical circuits, within functional columns and layers.

Animal fMRI: Pharmacologic Intervention

Hall B Thursday 13:30-15:30

1220. Anesthesia with Alpha-Chloralose in Rats: It Can Be Used for Longitudinal FMRI Studies

Benito de Celis Alonso1, Tanya Makarova1, Andreas Hess1

1Pharmacology and Toxicology, FAU Erlangen Nuremberg, Erlangen, Bayern, Germany

Animal experimentation in neurosciences requires the use of anesthetics for animal welfare and cooperation. Two of the most widely used anesthetics for functional magnetic resonance imaging (fMRI) of animals are Isofluorane (Iso) and Alpha-Chloralose (AC). Iso is an volatile drug shown to be suitable to obtain fMRI images at low concentrations(1). AC is an injectable anesthetic with strong functional-metabolic coupling but can create physiological problems. Therefore, it has been used as a non recoverable. There are studies were AC was used on human patients and others were AC was used to anaesthetize and recover dogs and cats (2,3). To our knowledge, the non-recoverable concept has not been challenged properly for fMRI. Here we present a protocol for AC anesthetic preparation and a fMRI study that shows that AC can be used as a recoverable anesthetic and has no effects on the fMRI results when animals are reused. Furthermore parallel behavioral studies on recovered rats show no effect on their brain and motor function.

1221. Noradrenergic Modulation of Auditory Processing in the Songbird Brain.

Colline Poirier1, Tiny Boumans1, Michiel Vellema1, Geert De Groof1, Marleen Verhoye1, Jacques Balthazart2, Annemie Van der Linden1

1Bio-Imaging Lab, Antwerp, Belgium; 2GIGA Neurosciences, Liège, Belgium

Song learning in songbirds shares a large number of features with human speech acquisition. The songbird brain is thus an excellent model to study the neural bases of vocal learning and complex sound processing. The aim of this spin-echo BOLD fMRI study was to investigate the role of noradrenalin in conspecific songs and bird’s own song perception. Depletion of noradrenergic inputs resulted in an enhanced differential activation by socially relevant auditory stimuli in the secondary auditory regions of the songbird brain. These results suggest that noradrenalin might play an inhibitory role in song discrimination.

1222. Role of Nitrite in Neurovascular Coupling: Nitric Oxide-Dependent and Independent Mechanisms

Barbora Piknova1, Ara Kocharyan2, Alan N. Schechter1, Afonso C. Silva2

1National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, United States; 2National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States

In addition to classic role of vasodilator, nitric oxide (NO) also acts as a neurotransmitter. NO role in neurovascular coupling and the possibility to restore the proper brain hemodynamics after its impairment in various NO-deficiency related diseases is of major importance. We studied the fMRI response to forepaw stimulation on á-chloralose anesthetized Sprague-Dawley rats at baseline, with NO production attenuated by nNOS inhibition and after NO and nitrite distribution. We found that exogenous NO and nitrite restore neurovascular response and that nitrite is more effective than direct NO donor. We hypothesize about additional vasodilatory pathways in case of nitrite metabolism.

1223. Qualitative Differences in the Brain Activation Effects of Cocaine and Mdma Determined with Bold Fmri in Rhesus Monkeys

Kevin Sean Murnane1, Leonard Lee Howell1

1Neuroscience, Emory University, Atlanta, GA, United States

Both cocaine and methylenedioxymethamphetamine (MDMA) are drugs with a high propensity for abuse yet they have distinct behavioral and neurochemical effects. We compared the changes in blood oxygenation elicited by cocaine (0.3 mg/kg, i.v.) and MDMA (0.3 mg/kg, i.v.) in rhesus monkeys using BOLD fMRI. The effects of cocaine were localized to dorsal prefrontal cortex (PFC) whereas MDMA’s were localized to ventral PFC. Therefore, the neural circuitry engaged by these compounds appears to regulate their behavioral effects. As such, the use of fMRI allows for a novel approach to determine the mechanism of drugs of abuse.

1224. De Novo Buprenorphine Phmri Effects in Conscious Rats Parallels Brain Activation in Humans

Lino Becerra1,2, Pei-Ching Chang1, James Bishop1, Jaymin Upadhyay1, Julie Anderson1, Gautam Pendse1, Smriti Iyengar3, Alexandre Coimbra4, Richard Baumgartner4, Adam Schwarz3, Jeffrey Evelhoch4, Erci Nisenbaum3, Brigitte Robertson5, Thomas Large5, David Bleakman3, Richard Hargreaves4, David Borsook1,2

1Imaging Consortium for Drug Development, McLean Hospital, Belmont, MA, United States; 2A A Martinos Center for Biomed. Imaging, MGH, Harvard Medical School, Charlestown, MA, United States; 3Eli Lilly and Co., Indianapolis, IN, United States; 4Merck and Co, West Point, PA, United States; 5Sepracor Inc., Marlborough, MA, United States

fMRI studies of rodents are confounded by the use of anesthetics, especially for the study of analgesics. Furthermore, there are no studies comparing pharmacological brain effects in humans and rodents of the same analgesics. In this work, we present results of pharmacological MRI (phMRI) of an opioid analgesic (buprenorphine) in conscious rats and compare the brain activations with results obtained in humans. Although brain structure and function differ between humans and rodents, some parallelism does exist and this thesis underpins much pre-clinical research. Translational results as presented here have the potential to bridge pre-clinical with clinical imaging studies.

1225. A FMRI Study to Decipher the Regional Effects of an Intraperitoneal Glucose Dose in the Fasted Rat Model

Kim O'Toole1, Diana Cash1, Steve C R Williams1, Po-Wah So1

1Neuroimaging Department, Institute of Psychiatry, KCL, London, United Kingdom

Glucosensing neurones regulate membrane potential and firing rates in response to ambient glucose levels, and generally located in areas involved in neuroendocrine function, nutrient metabolism and energy homeostasis. Using BOLD-MRI, we have studied the effects of a single intraperitoneal glucose tolerance dose in the brain of a fasted rat model. Glucose induced BOLD-MRI signal increases in various regions of the brain, including the hypothalamus and hippocampus, which are known to contain glucosensing neurones. Thus, BOLD-MRI may be used to a non-invasive tool assess the functional role of nutrients in the brain under different physiological states.

1226. Effect of the Novel Anti-Depressant Agomelatine Determined by Pharmacological MRI in the Rat.

Karen Elizabeth Davies1, Inna V. Linnik1, Shane Mckie2, Jennifer A. Stark3, Simon Luckman3, Laure Sequin4, Elisabeth Mocaer4, Mark Millan4, Bill Deakin2, Steve R. Williams1

1Imaging Science & Biomedical Engineering, University of Manchester, Manchester, United Kingdom; 2Neuroscience and Psychiatry Unit, University of Manchester, Manchester, United Kingdom; 3Faculty of Life Science, University of Manchester, Manchester, United Kingdom; 4Institut de Recherches Internationales, Servier, Courbevoie, France

phMRI was used to determine brain areas activated by the novel anti-depressant agomelatine at 3 doses. T2*-weighted GE images were acquired continuously before and after injection of agomelatine or vehicle in isoflurane-anaesthetized rats. A pseudoblock analysis was performed in SPM5, revealing significant areas of activation and deactivation including cortical, hippocampal and caudate regions. There was a marked effect of dose with more brain areas, more total voxels and higher Z-scores at a dose of 20mg/kg compared to either 10 or 40mg/kg. Agomelatine acts at both melatonin and serotonin receptors and both receptors are likely to be involved in these responses.

1227. Concurrent Pharmacological MRI and Electrophysiology to Investigate Neuropharmacological Modulation of Brain Function in the Rat

Christopher James Martin1, Nicola R. Sibson1

1Radiation Oncology and Biology, University of Oxford, Oxford, Oxfordshire, United Kingdom

The aim of this work was to combine pharmacological magnetic resonance imaging with electrophysiological recording of neuronal activity such that we might improve our understanding of: (1) the neural basis of neuroimaging signals; (2) the effects of neuropharmacological manipulations on neurovascular coupling and neuroimaging signals; and (3) neuroanatomical differences in the relationship between neuronal activity and neuroimaging signals. We report data from studies in which we use the serotonin (5-HT) releasing agent fenfluramine to increase endogenous 5HT levels and investigate the effects of this modulation on both baseline and stimulus-evoked fMRI signals and neuronal activity.

1228. BOLD PhMRI in the Rat on a Clinical 3T Scanner Using Cocaine Challenge

Edwin Heijman1, Duncan Jack Hodkinson2, Roland van de Molengraaf3, Brian Henry4, Shane McKie5, Charles Sio1

1Philips Research Europe, Philips, Eindhoven, Netherlands; 2Imaging Science and Biomedical Engineering, The University of Manchester, Manchester, United Kingdom; 3Life Science Facilities, Philips Research, Philips, Eindhoven, Netherlands; 4Translational Medicine Research Centre, Schering-Plough, Singapore, Singapore; 5Neuroscience and Psychiatry Unit, The University of Manchester, Manchester, United Kingdom

In this study we investigated the potential applications of a clinical 3T system for pharmacological MRI (phMRI) in the rat brain. Using a human 3T MRI scanner, a dynamic SE-EPI BOLD sequence was implemented to determine alterations between pre- and post-injection of 5 mg/kg cocaine in male Sprague-Dawley rats under isoflurane anesthesia. Data analysis was performed using pseudoblock analyses. Cocaine-saline subtraction across the time series, showed significant activations in cortico-limibc areas of the motor, retrosplenial, and piriform cortex, extending to subcortical areas of the antero-dorsal hippocampus. We conclude that pre-clinical phMRI studies can be performed using 3T clinical scanners.

1229. Effects of Doxorubicin on Brain Activity and Functional Connectivity in Rats

Alan S. Bloom1, Peter S. LaViolette2, Christopher R. Chitambar3, William Collier1, Sally J. Durgerian4, Balaraman Kalyanaraman2, Donna M. McAllister2, Carol L. Williams1, Kathleen M. Schmainda5

1Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, WI, United States; 2Biophysics, Medical College of Wisconsin, Milwaukee, WI, United States; 3Neoplastic Diseases and Hematology, Medical College of Wisconsin, Milwaukee, WI, United States; 4Neurology, Medical College of Wisconsin, Milwaukee, WI, United States; 5Radiology and Biophysics, Medical College of Wisconsin, Milwaukee, WI, United States

The purpose of this research was to investigate “chemobrain” at a mechanistic level by determining the effects of doxorubicin, one of the agents commonly used for the adjuvant chemotherapy of breast cancer, on brain function using fMRI and fcMRI in a rat model. . We observed in a small group of rats treated weekly with DOX that it alters brain activation by sensory stimulation particularly in regions associated with vision and that we are able to demonstrate resting state functional connectivity MRI in the anesthetized rat and that it is decreased by DOX treatment, particularly in the visual system.

Athersclerosis & Coronary MRI

Hall B Monday 14:00-16:00

1230. Strong Collision Approximation to Predict Iron Volume Fraction in Ex Vivo Atherosclerotic Rabbit’s Aorta

Raimo P. Joensuu1, Louise M A Anderson, 12, Anna E. Larsson1, Li-Ming Gan1, Malin E. Palmér1, Paul D. Hockings1

1AstraZeneca R&D Molndal, Mölndal, Sweden; 2Chalmers University of Technology, Gothenburg, Sweden

The purpose of this work was to evaluate the suitability of the strong collision approximation to predict the USPIO volume fraction in atherosclerotic rabbits’ vessel wall from the transverse relaxation time, T2*. There was an excellent agreement (R2 = 0.98) between the theory and the measurements for volume fractions larger than 15 ppm. For lower volume fractions the theory agrees with the measurements poorly. The strong collision model may predict correctly the volume fraction from the T2* map when every voxel contains a relatively high number of magnetic particles but fails if the region contains also voxels with few or no particles.

1231. Heparin-Polynitroxide Derivatives: First Application as Site Specific MRT Imaging Contrast Media for Vascular Wall

Maxim V. Terekhov1, Vasily Sen'2, Valery Golubev2, Stefan Weber3, Alexander W. Scholz4, Thomas Muenzel5, Andrei L. Kleschyov5, Laura Maria Schreiber3

1Department of Radiology, Section of Medical Physics, Johannes Gutenberg University Medical Center Mainz, Mainz, Germany; 2Institute of Problems of Chemical Physics, Russian Academy of Sciences, Russian Federation; 3Department of Radiology, Section of Medical Physics, Johannes Gutenberg University Medical Center Mainz, Mainz, Germany; 4Department of Anesthesiology, Johannes Gutenberg University Medical Center Mainz, Mainz, Germany; 5II-Department of Medicine, Johannes Gutenberg University Medical Center Mainz, Mainz, Germany

Cyclic nitroxides e.g. TEMPO are stable free radicals with multiple applications in MRI. Heparin is known to have a high affinity for the vascular extracellular structures. We propose that TEMPO could be delivered to the vascular wall by means of heparin-polynitroxide (HNR) derivatives where the nitroxide is linked with the heparin macromolecule. The T1,2 measurements show that HNR complexes provide the relaxivity contrast comparable with Gd-based media. The pilot MRI experiment with ex-vivo labeling of vascular wall with HNR demonstrate high potential of functionalized polynitroxide targeted to the specific structures of the vascular wall for diagnostic and therapeutic purposes.

1232. Clinical 3.0T Magnetic Resonance Scanner Can Be Used for Imaging of Mouse Atherosclerotic LesionsΦ

Xubin Li1,2, Huidong Gu1, Hongqing Feng1, Xiangke Du2, Bensheng Qiu1, Xiaoming Yang1

1Image-Guided Bio-Molecular Intervention Researchers, Department of Radiology; Institute for Stem Cel, University of Washington School of Medicine, Seattle, WA, United States; 2Radiology, Peking University People's Hospital, Beijing, China

The aim of this study was to explore the possibility of generating high-resolution MR images of atherosclerotic aortic walls/plaques of mice using a clinical 3.0 Tesla MR scanner. This study demonstrates that clinical 3.0T MR scanners can be used for high-resolution imaging of atherosclerotic vascular walls and lesions in mice, which is guaranteed with a specific mouse RF coil, an effective ECG-gating system, and a BB-MRI sequence.

1233. Detection of Coronary Artery Wall Inflammation in a Porcine Model Using Non-Contrast Enhanced MRI

Steen Fjord Pedersen1, William P. Paaske2, Troels Thiem3, Samuel A Thrysøe, Erling Falk3, Steffen Ringgaard, Won Yong Kim4

1Dept. of Cardiology, and MR-center, Aarhus University Hospital, Skejby, Aarhus, Denmark; 2Dept. of Cardiothoracic and Vascular Surgery T, Aarhus University Hospital, Skejby; 3Dept. of Cardiology, Aarhus University Hospital, Skejby; 4dept. of Cardiology, and MR-center, Aarhus University Hospital, Skejby

Inflammation seems to play a key role in destabilization of atherosclerotic plaques. Detection of Inflammatory activity within atherosclerotic plaques therefore has the potential to distinguish between vulnerable and stable plaques. Using a balloon injured porcine coronary artery, we examined whether edema as a sign of inflammation could be detected in the vessel wall by MRI using a T2-STIR (known to detect edema). After injury, the T2-STIR images showed a significant increase in vessel wall enhancement of 143% (CI95 = [39.6 - 142.5]; and areas with signal enhancement correlated well to inflammation and edema confirmed by histopathology.

1234. Coronary Artery Plaque Imaging: Comparison of Black-Blood MRI and 64-MDCT

Yi He1, Zhaoqi Zhang1, Qinyi Dai1, Wei Yu1, Biao Lu1, Zhanming Fan1, Jing An2, Lixin Jin3, Guobin Li4, Wolfgang Rehwald5, Renate Jerecic3, Debiao Li6

1department of radiology, An zhen hospital, Beijing, China; 2Siemens Mindit Magnetic Resonance, Siemens Healthcare, MR Collaboration NE Asia; 3Siemens Limited China, Siemens Healthcare, MR Collaboration NE Asia; 4Siemens Mindit Magnetic Resonance Ltd; 5Siemens Healthcare USA; 6Northwestern University, Chicago USA

This study was to evaluate the ability of black-blood coronary wall MRI to identify and classify coronary plaques by comparing with 64-MDCT.15 patients underwent black-blood coronary wall MRI and coronary 64-MDCT. In MRI, the plaque burden, maximal wall thickness, SNR, CNR in the coronary walls containing plaques were greater than those of the normal coronary walls.The SNR in the soft plaque was greater than those in calcified and mixed plaques. The conclusion was coronary wall MRI can identify coronary plaques, and has the potential to differentiate plaque types based on signal intensity.

1235. Non-Contrast Coronary Vessel Wall and Plaque Imaging Using Inversion Recovery Prepared Steady State Free Precession: Comparison with Plaque Characterization of 64 Detector Row CT

Takeshi Ishimoto1, Yasuyo Taniguchi2, Tosiaki Miyati3, Momoe Kawakami4, Takayuki Ikeda5, Hisaya Kusabe5

1Division of Health Science, , Graduate school of Medical, Kanazawa University, Kanazawa, Ishikawa, Japan; 2Department of Cardiology, Hyogo Brain and Heart Center, Himeji, Hyogo, Japan; 3Division of Health Science,, Graduate school of Medical, Kanazawa University, Kanazawa, Ishikawa, Japan; 4Radiology and Clinical Laboratory, Hyogo Brain and Heart Center, Himeji , Hyogo, Japan; 5Radiology and Clinical Laboratory, Hyogo Brain and Heart Center, Himeji, Hyogo, Japan

In the study, we sought to determine whether coronary vessel wall imaging using inversion recovery prepared SSFP correlate with atherosclerosis detected by 64 raw MDCT. IR-SSFP can be used to non-invasively visualize the coronary vessel wall and to detect the presence of (sub)clinical coronary atherosclerosis . HSI of IR-SSFP may be indicative of plaque inflammation and/or hemorrhage. Therefore, coronary plaque vulnerability could be predicted by cardiac MRI. Further studies are needed to define the importance of these findings in the detection and treatment of vulnerable plaques.

1236. Contrast-Enhanced Whole Heart Coronary MRI with Bolus Infusion of Gadobenate Dimeglumine at 1.5T

Peng Hu1, Jonathan Chan, Jouke Smink2, Beth Goddu, Kraig V. Kissinger, Lois A. Goepfert, Thomas H. Hauser, Neil M. Rofsky3, Warren J. Manning, Reza Nezafat

1Beth Israel Deaconess Medical Center, Boston, MA, United States; 2Philips Healthcare; 3Radiology, Beth Israel Deaconess Medical Center

We sought to investigate the contrast injection timing and rate for contrast-enhanced coronary artery MRI and compared the images acquired with optimized contrast timing to non-contrast T2-prep whole-heart SSFP coronary MRI at 1.5T. We studied time-resolved blood T1 after gadobenate dimeglumine (Gd-BOPTA) injection using three infusion schemes (bolus, slow infusion and hybrid). Subsequently, we evaluated an isotropic contrast-enhanced whole-heart coronary MRI method at 1.5T using an inversion-recovery SSFP sequence acquired after a bolus infusion of Gd-BOPTA. The contrast-enhanced coronary MRI increased blood SNR by 36% and increased coronary-myocardium CNR by 101%. There was no significant difference in image quality.

1237. 3D Flow-Insensitve Coronary Vessel Wall Imaging Using Phase Sensitive Inversion Recovery

Jingsi Xie1, Himanshu Bhat1, Zhaoyang Fan1, Debiao Li1

1Departments of Radiology and Biomedical Engineering, Northwestern University, Chicago, IL, United States

Developed a 3D flow-insensitive coronary vessel wall imaging technique.

1238. Contrast-Enhanced Whole-Heart Coronary MRA at 3.0T for the Evaluation of Cardiac Venous Anatomy

Heng Ma1, Lan Ge2, Qi Yang1, Dong Xu1, Han Li1, Qing Tang1, Jiangtao Liu1, Wen Qin1, Jing An3, Lixin Jin4, Renate Jerecic4, Xiangying Du1, Kuncheng Li1, Debiao Li2

1Xuanwu Hospital, Capital Medical University, Beijing, China; 2Radiology, Northwestern University, Chicago, IL, United States; 3Siemens Mindit Magnetic Resonance Ltd, Shenzhen, China; 4Siemens Ltd, Healthcare Sector, China

Fifty-one subjects underwent contrast-enhanced whole-heart coronary magnetic resonance angiography at 3.0T. All major cardiac veins, except for the vein of Marshall, could be depicted successfully.

1239. A New Approach for Single Breath-Hold Whole Heart Coronary MRA Using Highly-Accelerated Parallel Imaging with a 32-Element Coil Array

Jian Xu1,2, Daniel Kim3, Ricardo Otazo3, Sven Zuehlsdorff4, Xiaoming Bi4, Bernd Stoeckel1, Daniel Sodickson3

1Siemens Medical Solutions USA Inc., New York, NY, United States; 2PolyTechnic Institute of NYU, New York, NY, United States; 3Center for Biomedical Imaging,Department of Radiology, New York University, New York, NY, United States; 4Siemens Medical Solutions USA Inc., Chicago, NY, United States

To develop a new approach for high resolution 3D whole heart coronary MRA in a single breath-hold, which offers the potential to enhance imaging efficiency and spatial resolution without apparent misregistration between external RF coil calibration scan and imaging scan.

1240. Whole-Heart Water/Fat Resolved Spiral Imaging for Coronary MRA and Fatty Myocardial Infiltrations

Peter Börnert1, Kay Nehrke1, Holger Eggers1, Peter Koken1

1Philips Research Europe, Hamburg, Germany

Fat suppression is essential to improve contrast in MR coronary angiography (CMRA) but fat also contains helpful diagnostic information. In particular, the intra-myocardial fat represents an important diagnostic indicator that could have high prognostic value. Therefore, in this work whole heart CMRA-type imaging is proposed that delivers both, the coronary tree and the fat signal distribution at the same spatial resolution. Dixon-based chemical shift encoded spiral imaging is used allowing to separate water and fat and to benefits from the ƒ´Bo -based off-resonance correction. This concept was applied and validated in volunteers and shows that efficient CMRA and intra-myocardial fat detection is possible with large volume coverage.

1241. MR-Imaging of the Coronary Arteries of Mice in Vivo

Arno Nauerth1, Erich Treiber1, Claudia Oerther1, Ulrich Flögel2

1Bruker BioSpin MRI GmbH, Ettlingen, Germany; 2Institut für Herz- und Kreislaufphysiologie, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany

In this study the dynamic filling of the coronary arteries in mice was visualized by using a cryogenically cooled surface coil for SNR improvement and by using a self-gated method with full heart coverage which corrects for cardiac and respiratory motions. The results presents volume-targeted cine-MIPs.

1242. Analysis of Small Dilation Detection in Coronary Angiography

Travis B. Smith1, Krishna S. Nayak1

1Electrical Engineering, University of Southern California, Los Angeles, CA, United States

Estimation of coronary artery cross-sectional lumen area from MR images is now being used to assess the relationship between atherosclerosis and vasomotion response to endothelial-dependent stimuli. Typically, cross-sectional images of the coronary lumen acquired before and after administration of such stimuli are fit to circular templates to estimate the change in area. These studies have reported very small mean changes in lumen area. In this work, we develop a statistical framework for the detection of these subtle changes in lumen area using two images. We use this framework to relate detection performance to SNR requirements and minimum detectable dilation.

1243. Analysis of Coronary Vein Motion: Implications for MR Coronary Vein Venography

Pierre John Watson1, Jonathan D. Suever2, John N. Oshinski1

1Radiology, Emory University, Atlanta, GA, United States; 2Biomedical Engineering, Georgia Institute of Technology

The periods of low motion of the coronary veins during the cardiac cycle were quantified using 3D magnetic resonance coronary venograms (cMRV) in 16 patients with ischemic heart disease. The temporal location and duration of these periods were determined using the frame-to-frame displacement method on the coronary sinus. The patients were classified as either systolic or diastolic dominant based on the duration of the periods. The majority of patients were systolic dominant although about a third of the patients either had a very short diastolic period or lacked it completely.

1244. Motion Correction Coeeficient Pre-Analysys Method for Whole-Heart Magnetic Resonance Coronary Angiography (Wh Mrca) for Use in a Clinical Setting

Yuki Ohmoto1, Rieko Ishimura2, Takashi Yoshida3, Miho Yabuyamada3, Junji Takahashi3, Shigehide Kuhara4, Sachiko Isono4, Ayako Ninomiya4, Mitsue Miyazaki4, Hiroyuki Tsuji1, Yasuji Arase1

1Health Management Center, Toranomon Hospital, Minato-ku, Tokyo, Japan; 2Cardiovascular Center, Toranomon Hospital; 3Radiology, Toranomon Hospital; 4MRI systems Division, Toshiba Medical Systems Corporation

Whole-Heart Magnetic Resonance Coronary Angiography (WH MRCA) is a very useful tool for screening for coronary artery disease and usually performed during free breathing with real time motion correction (RMC). We have developed a Motion Correction Coefficient Pre-Analysis Method to obtain an appropriate RMC coefficient before the WH MRCA scan and performed the feasibility study of this method by evaluating the relation between the coefficient of RMC and the image quality for health screening cases retrospectively. The results showed that this method is expected to be very useful in the clinical application of WH MRCA.

1245. Global-To-Local Tandem Method for Detecting the Coronary Stationary Period for Whole-Heart Magnetic Resonance Coronary Angiography (Wh Mrca)

Ayako Ninomiya1, Shigehide Kuhara1, Tomohisa Okada2, Tetsuo Sato3, Kotaro Minato3, Shoutaro Kanao2, Kaori Togashi2

1MRI Systems Division, Toshiba Medical Systems Corporation, Otawara-shi, Tochigi, Japan; 2Kyoto University Hospital, Kyoto, Japan; 3Nara Institute of Science and Technology, Nara, Japan

We have developed the Global-to-Local Tandem Method to detect the coronary stationary period for WH MRCA, in which the coronary stationary period is roughly analyzed by the global method and then more precisely analyzed by the local method. We have also conducted clinical feasibility studies. Results suggest that The Global-to-Local Tandem Method can robustly detect the coronary artery stationary period in WH MRCA (Whole Heart Magnetic Resonance Coronary Angiography). It is therefore concluded that this method should prove to be very useful for clinical WH MRCA examinations.

1246. Retrospective Motion-Adapted Smart Averaging for Free-Breathing Cardiac MRI

Alan Christopher O'Connor1,2, Mehdi Hedjazi Moghari1, Peng Hu1, Dana C. Peters1, Warren J. Manning1, Reza Nezafat1, Roger Ware Brockett2

1Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States; 2SEAS, Harvard University, Cambridge, MA, United States

Navigator gating is an accepted method for reducing the effect of respiratory motion in cardiac MRI; however, it does not exploit the fact that different spatial frequencies are more or less sensitive to the respiratory motion. We present a smart motion-adapted averaging method that retrospectively corrects for respiratory motion by combining data from k-space lines of multiple acquisitions using weights determined by the navigator signal.

1247. CoSMo: Compressed Sensing Motion Correction for Coronary MRI

Mehdi Hedjazi Moghari *1, Mehmet Akçakaya *,12, Alan O'Connor, 12, Peng Hu1, Vahid Tarokh2, Warren J. Manning1, Reza Nezafat1

1Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States; 2Harvard University, Cambridge, MA, United States

We examine the feasibility of using compressed sensing to reduce artifacts due to respiratory motion. Respiratory motion causes image artifacts and ghosting in cardiac imaging. Respiratory navigators are one of the methods used to mitigate these artifacts for free-breathing scans, where k-space lines falling outside a pre-defined gating window are reacquired until the whole k-space is filled. In this study, we introduce CoSMo, a compressed sensing-based method for reconstructing images without having to reacquire k-space lines rejected by the navigator.

1248. New Approach for Patient-Specific Estimation of Cardiac Motion Due to Respiration

Florencio Rusty Baldomaro Punzalan1, Tetsuo Sato1, Tomohisa Okada2, Shigehide Kuhara3, Kaori Togashi2, Kotaro Minato1

1Graduate School of Information Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan; 2Department of Diagnostic Radiology, Kyoto University Hospital, Kyoto, Japan; 3MRI Systems Division, Toshiba Medical Systems, Tochigi, Japan

Respiratory motion compensation for cardiac imaging requires a patient-specific knowledge of the heart’s motion. In this study, the respiratory-induced motion of the upper and lower part of the heart was investigated during free-breathing. We observed significant inter-subject variation of upper and lower heart motion tracking factors. The tracking factor for the lower part is larger than the upper part for all subjects. This will help motion models account for the different displacements and velocities of coronary vessels located in the atrio-ventricular groove (RCA and LCX) and the apex (LAD) which are located in the lower and upper heart, respectively.

1249. Which Factors Influence MRI In-Stent Lumenvisibility of Coronary In-Stent Stenosis? an In-Vitro Model Investigation

Gerrit Schönwald1, Gregor Schaefers2, Georg Haltern3, Brigitte Kipfmüller4

1University Witten/Herdecke, Gelsenkirchen, NRW, Germany; 2MR:comp GmbH, Gelsenkirchen, Germany; 3HELIOS Heart Center , Wuppertal, Germany; 4University of applied Science Gelsenkirchen, Germany

Purpose Development of a standardized procedure to evaluate which factors need to be optimized for quantification of in-stent stenosis by analysis of lumenvisibility in a static MRI model of coronary in-stent stenosis. Methods Stents were placed into tubes and equipped with artificial restenosis made of a pre-investigated material. The tubes were placed in a phantom. A 1.5 and a 3 Tesla MR-system were used. Results Quantification of in-stent stenosis was limited in stainless steel stents and cobalt-chromium stents by artifacts. Tantalum stent showed a lower rate of artifacts. Conclusion Image quality was strongly depended from stent material and stent design.

Vessel Wall Imaging (Non-Coronary)

Hall B Tuesday 13:30-15:30

1250. Comparison Between Ungated Multi-Slice and Gated Single-Slice Double Inversion Recovery Prepared Black-Blood Fast Spin Echo Sequences Applied at 3T

Andrew J. Patterson1, Victoria E. Young1, Martin J. Graves1, Jonathan H. Gillard1

1Radiology, University of Cambridge, Cambridge, England, United Kingdom

Double inversion recovery prepared, fast spin echo, black blood imaging has been widely used for assessing carotid plaque tissue composition. The protocol is used to obtain T1-, T2- and PD-weighted contrast. This study compares the between subject and within subject differences in the signal-to-noise ratio and the contrast-to-noise ratio from single- and multi-slice acquisition using both a gated and ungated trigger.

1251. Black Blood Imaging of Carotid Plaque Using Spatial Labeling with Multiple Inversion Pulses Prepared Spoiled Gradient Recalled Sequence

Hao Shen1, Guang Cao2, QingJun Wang3

1Applied Science Laboratory, GE Healthcare, Beijing, China; 2Applied Science Laboratory, GE Healthcare, Hong Kong, China; 3Department of Radiology, Chinese PLA General Hospital, Beijing, China

Black blood is important in carotid plaque characterization. In this study, we developed a black blood spoiled gradient recalled sequence by using spacial labeling with multiple inversion pulses preparation.

1252. High Resolution 3D Black Blood Carotid Artery Imaging Using 3D TSE Sequence with Non-Selective Refocusing RF and Inner Volume Imaging Technique.

Seong-Eun Kim1,2, Scott McNally2, Laura K. Findeiss2, Jordan Hulet3, John Roberts1,2, Eun-Kee Jeong1,2, Dennis L. Parker1,2, Gerald S. Treiman4,5

1UCAIR, University of Utah, Salt Lake City, UT, United States; 2Department of Radiology, University of Utah, Salt Lake City, UT, United States; 3Department of Biomedical Informatics, University of Utah; 4Department of Surgery, University of Utah, Salt Lake City, UT, United States; 5Veterans Affair, VASLCHCS, Salt Lake City, UT, United States

2D TSE with DIR is the current technique for identification of the component of carotid plaque. This approach is limited by inadequate spatial resolution that is often necessary to identify small areas of plaque components. 3D imaging offers the potential to improve spatial resolution. We have utilized 3D TSE with non-selective 180o RF and have implemented an inner volume imaging(IVI) technique. The non-selective 180o RF allow significantly more echoes to be acquired resulting in more efficient 3D scan. IVI technique reduces the field of view in the phase encoding direction and requires fewer phase encoding line, further reducing scan time.

1253. Intravascular 3.0T MR Imaging: A Feasibility Study in Swine

Yanfeng Meng1,2, Feng Zhang1, Huidong Gu1, Jinnan Wang3, Chun Yuan1, Zhaoqi Zhang2, Bensheng Qiu1, Xiaoming Yang1

1Radiology, University of Washington, Seattle, WA, United States; 2Radiology, Beijing Anzhen Hospital, Beijing, China; 3Clinical Sites Research Program, Philips Research North America, Briarcliff Manor, NY, United States

This study was to validate the feasibility of generating intravascular 3T MRI of deep-seated arteries of near-human-sized swine by using a 3T-MR compatible MR-imaging guidewire (MRIG). For in vitro testing, we compared SNRs generated by a 0.032-inch MRIG and surface coils. For in vivo validation, we performed intravenous MRI of the parallel-run iliofemoral arteries with this MRIG. The SNR by the MRIG was higher than surface coils, and the iliofemoral arterial walls were clearly delineated with the MRIG at a higher SNR than surface coils. This study establishes the groundwork for further intravascular 3T MRI of deep-seated arteries in humans.

1254. Histology Assisted Validation of Automatic Detection of Soft Plaque in Vessel Wall Images by Using Optimal Number of MR Sequences

Ronald van 't Klooster1, Andrew J. Patterson2, Victoria E. Young2, Jonathan H. Gillard2, Johan H.C. Reiber1, Rob J. van der Geest1

1Division of Image Processing, Department of Radiology, Leiden University Medical Center, Leiden, Netherlands; 2University Department of Radiology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, United Kingdom

Extensive MR vessel wall imaging protocols are used to identify unstable plaques, which play an important role in the progression of atherosclerosis. Comparison was made between automatic plaque detection, by a supervised classification system, and histology assisted manual segmentation. Experiments show that the automatic detection of unstable plaque is in good agreement with the manual segmentation. Moreover, the STIR and DWI sequences show an improvement over the T2w and PDw sequences. Automatic detection of soft plaque may be feasible by using a limited number of MR sequences, saving both MRI system and image analysis time.

1255. Improved Calcification Detection Accuracy on Human Atherosclerotic Plaque Using Ultra-Short TE (UTE) Imaging

Jinnan Wang1, Marina S. Ferguson2, Niranjan Balu2, Chun Yuan2, Peter Boernert3

1Clinical Sites Research Program, Philips Research North America, Seattle, WA, United States; 2University of Washington; 3Philips Research Europe

Ultra-short TE (UTE) images can provide positive contrast for short T2 species when combined with imaging techniques like dual-echo subtraction or magnetization preparation. Although the calcified regions identified on UTE images were demonstrated to agree with CT images, its accuracy has not been validated against histology. This study is aimed at comparing the accuracy of UTE calcification detection in human carotid plaques against regular turbo spin echo MR images, as well as validating it against histology.

1256. Response of the Carotid Vessel Wall to Lipid-Lowering Therapy: Time Course of T1 and T2-Weighted Signal Variation

Li Dong1, William Sean Kerwin1, Chun Yuan1, Xue-Qiao Zhao1

1University of Washington, Seattle, WA, United States

We hypothesized that lipid-lowering therapy leads to biological changes in arterial walls that result in altered MRI contrast, even in the absence of a developed necrotic core. In a carotid MRI study of atorvastatin, 42 subjects exhibited no necrotic core. Within this group, no measurable change in wall thickness occurred over 3 years, but a highly significant (p 0.2). Compared to NV, [NAA]/[Cr] was reduced (by 10%) in SV-ON (p = 0.006), but not in SV-OFF (p = 0.55). The GABA data showed difference between SV-OFF and SV-ON (p = 0.05).

2140. Asymmetry Patterns of Association Fibers in Schizophrenia: Preliminary Results Using Diffusion Spectrum Imaging Tractography

Yu-Chun Lo1, Su-Chun Huang2, Hai-Gwo Hwu3, Chih-Min Liu3, Chen-Chung Liu3, Wen-Yih Isaac Tseng2,4

1Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan, Taiwan; 2Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan, Taiwan; 3Department of Psychiatry, National Taiwan University Hospital, Taipei, Taiwan; 4Center for Optoelectronic Biomedicine, National Taiwan University College of Medicine, Taipei, Taiwan

Three association fibers connecting the frontal and temporal lobes and three commissural fibers connecting the bilateral orbitofrontal lobes, inferior frontal gyri, and superior temporal gyri related to the social and language functions that might serve the neuropsychopathology of patients with schizophrenia inferred from diffusion spectrum imaging tractography. In neurotypical participants, a consistent leftward asymmetry in the three pairs of association fibers was found. However, adults with schizophrenia did not demonstrate such asymmetry. Lack of leftward asymmetry in schizophrenia may imply a disruption in the normal pattern of structural and functional connectivity in frontal-temporal brain regions.

2141. White Matter Abnormalities Associated with Neurological Soft Signs in First-Episode Schizophrenia: A Diffusion Tensor Imaging Study.

Christine Rodriguez-Régent1, Sabine Mouchet-Mages2, Sebastian Rodrigo, Marie-Odile Krebs2, Catherine Oppenheim, Jean-François Meder

1Department of Morphologic and Functional Imaging, University Paris Descartes, Sainte Anne Hospital, PARIS, France; 2Pathophysiology of Psychiatric Diseases, University Paris Descartes, Sainte Anne Hospital, PARIS, France

Schizophrenic patients often present with neurological soft signs (NSS) but the cerebral changes underlying these signs are poorly understood. This study examines the microstructural changes associated with NSS using Diffusion Tensor Imaging. Forty-five patients with first-episode schizophrenia underwent DTI and a neurological examination. Fractional anisotropy (FA), calculated using a voxel based analysis, was analyzed with NSS scores. FA was negatively correlated with NSS scores in the white matter of the right prefrontal, left occipital and right parietal areas. Thus, this is the first study which confirms that microstructural changes of white matter are associated with NSS in schizophrenia.

2142. Interaction of Hippocampal Volume and N-Acetylaspartate Concentration Deficits in Schizophrenia: A Combined MRI and 1H-MRS Study at 3 T

Florian Schubert1, Andreas Klaer2, Martina Ballmaier2, Karolina Leopold2, Ines Haeke2, Martin Schaefer3, Ruediger Bruehl1, Juergen Gallinat2

1Physikalisch-Technische Bundesanstalt, Berlin, Germany; 2Charite University Medicine, Berlin, Germany; 3Kliniken Essen, Essen, Germany

We used single voxel 1H-MRS at 3 Tesla to measure absolute NAA concentrations and, as a gold standard of CNS volumetry, a validated delineation protocol for the hippocampus to study the interaction between between hippocampal NAA reduction and volume deficits in 29 schizophrenic patients and 44 controls. The hippocampus of the patients exhibited a significantly smaller volume and lower NAA concentration than that of healthy controls. For schizophrenic patients a significant negative correlation between hippocampal NAA concentration and volume was observed. The results argue for a coexistent neurochemical and structural deficit in the hippocampus of schizophrenic patients.

2143. An MRI Study of the Caudate Nucleus in Euthymic Bipolar I Disorder

Louise Emsell1, Camilla Langan1, Sarah Hehir1, Helen Casey1, Wil van der Putten1, Peter McCarthy1, Rachel Skinner1, Dara M. Cannon1, Colm McDonald1

1NUI Galway, Galway, Ireland

Bipolar disorder is a complex illness characterised by extremes of mood. It is likely that subtle changes in neuroanatomy contribute to the underlying aetiopathology of the disorder. This study sought to identify differences in the volume of the caudate nucleus in a prospectively confirmed sample of 59 remitted patients compared to 59 individually age and gender matched healthy controls to identify trait related anatomical changes. We did not find a main of effect of diagnosis. However,we did detect gender differences in caudate volume (F>M),age-related volumetric decrease across the study population and a main effect of family history in patients.

2144. Brain Matter Corrected Quantification of Phosphomono- And Phosphodiesters in the Brain of Patients with Schizophrenia

Wolfgang Weber-Fahr1, Mathias Zink2, Andreas Meyer-Lindenberg2, Monika Uhrig1, Nuran Tunc-Skarka1, Mareen Hoerst1, Helga Welzel-marquez1, Alexander Sartorius2, Gabriele Ende1

1Neuroimaging, Central Institute of Mental Health, Mannheim, NA, Germany; 2Dept. Psychiatry, Central Institute of Mental Health, Mannheim, NA, Germany

A 3D-whole head RINEPT sequence was used together with point-spread function corrected tissue segmentation for robust absolute quantification of spectral edited Phosphomono- and –diester-signals in the brains of schizophrenic patients and controls. The corrected metabolite concentrations show a significant reduction of Phosphocholine and Glycerophosphocholine (GPC) in the basal ganglia and thalamus of schizophrenic patients compared to controls. GPC was also significantly lower in the cerebellum while Phosphorylethanolamine showed a trend for lower concentration in patients in the frontal region.

2145. Altered Fiber Radial Diffusivity in Schizophrenia Revealed by HARDI

Xin Hong1,2, Lori R. Arlinghaus3, Herbert Y. Meltzer4, Sohee Park5, Adam W. Anderson, 2,3

1Institute of Imaging Science, Vanderbilt University , Nashville, TN, United States; 2Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, United States; 3Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States; 4Department of Psychiatry, Vanderbilt University, Nashville, TN, United States; 5Department of Psychology, Vanderbilt University, Nashville, TN, United States

We performed a group comparison of the diffusion properties and intravoxel fiber coherence estimated by FORECAST analysis. Significantly higher FA is found in schizophrenia patients compared to healthy controls in the left superior longitudinal fasciculus and bilateral internal capsules. In all three regions, strong negative correlation between FA and radial diffusivity is found at both voxel and cluster levels, even after controlling for coherence variation. Significantly lower coherence is found between the two groups at the cluster level, but not voxel level. Our results suggest the altered FA was mainly due to structural rather than organizational changes in these regions.

2146. Comparison of Different CSF Correction Methods in a MRS Study of Depressed Psychiatric Patients

John DeWitt Port1, Ileana Hancu2, Heidi Alyssa Edmonson1, Zhonghao Bao3, Mark A. Frye4

1Radiology, Mayo Clinic, Rochester, MN, United States; 2GE Global Research Center, Niskayuna, NY, United States; 3Information Services, Mayo Clinic, Rochester, MN, United States; 4Psychiatry, Mayo Clinic, Rochester, MN, United States

Various methods have been used to correct for the amount of CSF within spectroscopic voxels. However, it remains unclear which method is best. We performed CSF correction on an MRS dataset comparing depressed psychiatric patients to normal controls, using the ratio to creatine as well as two anatomically-based CSF correction methods. All three CSF correction methods yielded significant results for most statistical comparisons; ROC analysis demonstrated no single CSF correction technique to be better than the others. If the metabolite value used in the denominator is stable, ratios may actually improve statistical sensitivity relative to anatomically-based CSF correction methods.

2147. fMRI and Connectivity Effects of Electro-Convulsive Therapy (ECT) in Depressed Patients

Erik B. Beall1, Mark J. Lowe1, Michael D. Phillips1, Steve Jones1, Pallab K. Bhattacharyya1, David Muzina2

1Radiology, Cleveland Clinic, Cleveland, OH, United States; 2Psychiatry, Cleveland Clinic, Cleveland, OH, United States

ECT is a safe and effective treatment for depression. However its mechanisms have not been studied with the BOLD effect in a pre- and post-ECT fMRI and connectivity study. We present preliminary results that show reduced activation and connectivity in response to working memory and affective tasks.

2148. Decreased Anterior Cingulate Cortex GABA in Depressed Adolescents Measured by Proton MRS at 3T

Vilma Gabbay1, Xiangling Mao2, Yisrael Katz1, Aviva Pazner1, James S. Babb1, Dikoma C. Shungu2

1NYU Child Study Center, NYU School of Medicine, New York, NY, United States; 2Radiology, Weill Cornell Medical College, New York, NY, United States

Adolescent major depressive disorder (MDD) is a serious public health concern as it often leads to suicide. However, limited research has been conducted to date in this clinical population. This is the first study to examine in vivo γ-aminobutyric acid (GABA) in adolescents with MDD. Using proton MRS, levels of GABA were measured in the anterior cingulate cortex of adolescents with MDD and found to be decreased compared to matched healthy control subjects. This finding supports the notion that GABA abnormalities may be involved early in the etiology of MDD.

2149. Reduced Functional Connectivity in Major Depression: A Whole Brain Study of Multiple Resting-State Networks

Ilya M. Veer1,2, Christian F. Beckmann3,4, Evelinda Baerends1,2, Marie J. van Tol1,5, Luca Ferrarini6, Julien R. Milles6, Dick J. Veltman7, Andre Aleman8, Mark A. van Buchem1,2, Nic J. van der Wee1,5, Serge A. Rombouts1,2

1Leiden Institute for Brain and Cognition (LIBC), Leiden, Netherlands; 2Department of Radiology, Leiden University Medical Center (LUMC), Leiden, Netherlands; 3FMRIB, University of Oxford, Oxford, United Kingdom; 4Department of Clinical Neuroscience, Imperial College London, London, United Kingdom; 5Department of Psychiatry, Leiden University Medical Center (LUMC), Leiden, Netherlands; 6Department of Radiology, Division of Image Processing, Leiden University Medical Center (LUMC), Leiden, Netherlands; 7Department of Psychiatry, Free University Medical Center (VUMC), Amsterdam, Netherlands; 8BCN Neuroimaging Center, University of Groningen, Groningen, Netherlands

Major depression is associated with abnormal function of a large-scale mood processing and regulating brain circuit of interconnected regions. Therefore, resting-state (RS) functional connectivity networks were investigated in a group of 19 medication-free patients diagnosed with major depressive disorder without comorbidity, and 19 age- and gender-matched healthy controls. Using independent component, 13 relevant RS networks were found for the entire group. Adopting a dual regression method, subject specific maps were calculated and subsequently used for permutation analysis. We found decreased functional connectivity in three networks, which may relate to the affective and cognitive symptoms in major depression.

2150. Investigating Transverse Relaxation Time Abnormalities in Autism

Yann Gagnon1,2, N Rajakumar3, Neil Gelman1,2, Peter Williamson3, Dick Drost1,2, Jean Théberge1,2, Rob Nicolson3

1Imaging, Lawson Health Research Institute, London, Ontario, Canada; 2Medical Biophysics, University of Western Ontario, London, Ontario, Canada; 3Psychiatry, University of Western Ontario

Quantitative transverse relaxation time (T2) imaging offers a unique opportunity to evaluate the neurobiology of brain tissue. In the current study, we further localize our previously reported overall white matter T2 increase in a sample of children with autism to developmentally relevant neuroanatomic white matter regions.

2151. Aberrant Neurodevelopment of the Social Cognition Network During Adolescence in Autism Spectrum Disorders

Chun-Wei Lan1, Kun-Hsien Chou2, I-Yun Chen3, Ya-wei Cheng3, Jean Decety4, Yang-Teng Fan3, Ching-Po Lin1,3

1Institute of Biomedical Imaging and Radiological Sciences, National Yang Ming University, Taipei, Taiwan; 2Institute of Biomedical Engineering, National Yang Ming University, Taipei, Taiwan; 3Institute of Neuroscience, National Yang Ming University, Taipei, Taiwan; 4Departments of Psychology and Psychiatry, The University of Chicago, Chicago, United States

The autism spectrum disorders (ASD), during childhood, undergoes precocious growth, followed by maturation deceleration. But how the ASD brain changed during adolescence is unclear. We enrolled 25 male adolescents with ASD and 25 controls for voxel-based morphometric analysis. Global brain volume enlargement of ASD did not persist into adolescence. The right inferior parietal lobule and posterior cingulate cortex, a role in social cognition, had a significant interaction of age by group as indicated by an accelerated age-related loss in the adolescents with ASD but an age-related gain in the controls. The findings provided evidence of aberrant neurodevelopment in ASD.

2152. White Matter Abnormalities in Boys with Autism Spectrum Disorders: Preliminary Evidence from Diffusion Tensor Imaging

Sung-Yeon Park1, Se-Hong Oh1, Hyo-Woon Yoon1, Young-Bo Kim1, Zang-Hee Cho1, Keun-Ah Cheon2

1Neuroscience Research Institute, Gachon University of Medicine and Science, Incheon, Korea, Republic of; 22Division of child and Adolescent Psychiatry, Department of Psychiatry, Kwandong University College of Medicine, Kyunggi-Do, Korea, Republic of

Autism spectrum disorders (ASD) are characterized by qualitative impairments of reciprocal social interaction and deficits in communication, and stereotyped or repetitive pattern of behavior. A few reports have shown the abnormalities of white matter in autism using diffusion tensor imaging (DTI), however there is still lack of evidence showing strong relation to abnormalities in white matter structural integrity with autism. We enrolled thirty four male subjects (17 ASD, 17 healthy controls, matched on age, IQ, handedness.). Our preliminary findings which showed significant reduction of FA in white matter structure related social cognition in ASD subjects compared control subjects support previous findings that social brain structure may be disrupted in ASD. These findings will help on understanding of more advanced neurobiological basis underlying the social deficits in ASD.

2153. Imaging Myelin in Autism

Janneke Zinkstok1, Eileen Daly1, Christine Ecker1, Patrick Johnston1, Shannon Kolind2, Declan Murphy1, Sean Deoni2

1Section of Brain Maturation, Institute of Psychiatry, London, United Kingdom; 2Centre of Neuroimaging Sciences, Institute of Psychiatry, London, United Kingdom

Using the novel Multi-Component Driven Equilibrium Single Pulsed Observation of T1 and T2 (mcDESPOT) method, we quantitatively compared myelin content between individuals with autism and healthy controls. We found significantly reduced myelin content in adults with autism in brain regions previously implicated in autism, including the body of the corpus callosum, and in frontal, temporal, parietal and occipital regions; and in white matter tracts including the left and right uncinate, the left inferior occipitofrontal tract, the left inferior cerebellar peduncle, the left arcuate, the right anterior segment, the left inferior and superior longitudinal fasciculus, and the posterior segments bilaterally.

2154. Inter-Subject Comparison of Fractional Anisotropy in Attention-Deficit/hyperactivity Disorder

Tzu-Chao Chuang1, Sheng-Po Huang1, Pinchen Yang2, Ming-Ting Wu3,4

1Electrical Engineering, National Sun Yat-Sen University, Kaohsiung, Taiwan, Taiwan; 2Psychiatry, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan, Taiwan; 3School of Medicine, National Yang-Ming University, Taipei, Taiwan, Taiwan; 4Radiology, Kaohsiung Veteran General Hospital, Kaohsiung, Taiwan, Taiwan

In this study, white matter abnormalities of attention-deficit hyperactivity disorder were investigated using diffusion tensor imaging. Two different algorithms, including the well-known voxel-based morphometry (VBM) method and recently proposed tract-based spatial statistics (TBSS), were applied for inter-subject comparison. 26 male adolescents (12 ADHD patients and 14 age-matching control subjects) were recruited in this study. Significant decrease of FA was observed on white matter tracts widespread in a scattering pattern by the use of both methods in patients compared to the control group.

2155. MRS Measurement of GABA and Glutamate-Glutamine in Frontal Cortex in Obsessive-Compulsive Disorder

Lawrence Steven Kegeles1,2, H. Blair Simpson1, Xiangling Mao3, Rena Staub1, Dikoma C. Shungu3

1Psychiatry, Columbia University, New York, NY, United States; 2Radiology, Columbia University, New York, NY, United States; 3Radiology, Weill Cornell Medical Center, New York, NY, United States

This MRS study addressed GABA and glutamate-glutamine levels in a hypothesized abnormal neurochemical circuit in obsessive-compulsive disorder (OCD). Recent animal and human studies have implicated the glutamate system in OCD in these abnormalities. We used the J edited spin echo difference method to evaluate glutamate-glutamine and GABA in two frontal cortical regions, the anterior cingulate and dorsolateral prefrontal cortex in OCD. We found no differences between OCD subjects and controls in either measure in either brain region, suggesting that further studies are needed to fully characterize the neurochemistry of the hypothesized abnormal circuitry in OCD.

2156. Impaired Default-Mode Networks of Affective Disorders: Evidences of Image-Guided Proton MRS

Tzu-chen Yeh1,2, Chih-Ying Lin2, Cheng-Wen Ko3, Ton-Ping Su4, Wan-Yuo Guo5, Jen-Chuen Hsieh2, Low-Ton Ho1

1Department of Medical Research and Education, Taipei Veterans General Hospital, Taipei, Taiwan, Taiwan; 2Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan, Taiwan; 3Department of Computer Science and Engineering, National Sun Yat-sen University, Kaohsiung, Taiwan, Taiwan; 4Department of Psychiatry, Taipei Veterans General Hospital, Taipei, Taiwan, Taiwan; 5Department of Radiology, Taipei Veterans General Hospital, Taipei, Taiwan, Taiwan

The spatial template of default-mode network (DMN) has been constructed and shown precuneus/posterior cingulate areas (PC, Brodmann area 31) with highest reproducibility in 60 normal subjects. High resting metabolic rate of DMN was implied by previous deoxy-glucose positron emission tomography. In this study of affective disorders (bipolar and major depressive disorders), bioenergetics of Brodmann area 24 and DMN was probed by total creatine using real-time localized image-guided proton magnetic resonance spectroscopy (ig-HMRS) and LCModel quantification. As compared to affective disorders, higher metabolism of PC (representing DMN) in normal subjects was supported by higher total creatine concentration.

2157. Glutamate Levels in the Anterior Cingulate Cortex Correlate with Self-Reported Impulsivity in Patients with Borderline Personality Disorder and Healthy Controls

Mareen Hoerst1,2, Wofgang Weber-Fahr1, Nuran Tunc-Skarka1, Matthias Ruf1, Martin Bohus2, Christian Schmahl2, Gabriele Ende1

1Department of Neuroimaging, Central Institute of Mental Health, Mannheim, Germany; 2Department of Psychosomatic Medicine and Psychotherapy, Central Institute of Mental Health, Mannheim, Germany

Dysfunction and deficits in the structure of the anterior cingulate cortex (ACC) have been reported in borderline personality disorder (BPD). Impulsivity belongs to the key features of BPD and can be related to ACC function. In this study we found significantly increased self-reported impulsivity and higher levels of glutamate in the anterior cingulate cortex in subjects with BPD as compared to healthy controls. In both groups the ACC glutamate concentrations were positively correlated with self-reported impulsivity.

2158. Grey Matter Abnormalities in Adult Attention Deficit/hyperactivity Disorder as Measured with Structural MRI

Natalia del Campo1,2, Julio Acosta-Cabronero3,4, Samuel R. Chamberlain, Dowson Jonathan5, Tim D. Fryer, 4, Trevor W. Robbins, Barbara J. Sahakian5, Ulrich Muller

1Psychiatry, University of Cambridge, Cambridge, Cambs, United Kingdom; 22Behavioural and Clinical Neuroscience Institute, Cambridge, Cambs, United Kingdom; 3Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom; 4Wolfson Brain Imaging Centre; 5Department of Psychiatry

Attention deficit/hyperactivity disorder (ADHD) is the most prevalent psychiatric disorder in children. To date, little is known about the persistence and stability of anatomical changes in ADHD across the lifespan. 16 adult ADHD patients and 17 healthy controls undertook structural magnetic resonance imaging. Using cluster-based permutation analysis we found that ADHD patients had reduced grey matter density in distributed circuitries including the right inferior and middle frontal cortex, as well as bilateral putamen, hippocampus, amygdala and cerebellum. These findings add to a growing body of evidence implicating abnormalities in fronto-striatal, fronto-cerebellar and limbic circuitries in ADHD.

2159. A Systematic Analysis of Association Fiber Tracts in Chronic Alcoholics Found Significant Deficit of White Matter Integrity in Superior Longitudinal Fasciculus Using Diffusion Spectrum Imaging Tractography

Cheng-Liang Liu1, I-Chao Liu2, Wen-Yang Chiang3, Fang-Cheng Yeh4, Li-Wei Kuo1, Wen-Yih Isaac Tseng1,5

1Center for Optoelectronic Biomedicine, National Taiwan University College of Medicine, Taipei, Taiwan; 2School of Medicine, Fu Jen Catholic University, Taipei, Taiwan; 3The Methodist Hospital Research Institute, Weill Medical College of Cornell University, Houston, TX, United States; 4Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA, United States; 5Department of Medical Imaging, National Taiwan University Hospital, Taipei, Taiwan

In this study, we investigated the relationship between the effect of alcoholic use and the microstructural alteration of seven association fiber tracts using diffusion spectrum imaging tractography and tract-specific analysis. The metric of generalized fractional anisotropy (GFA) was used to identify the difference between control and alcoholic groups. Among all the association fiber tracts, a significant GFA deficit was found in bilateral superior longitudinal fasciculus for chronic alcoholics. A future study to analyze the segmented parts of the tract is needed to further reveal the subtle change of microstructural alteration of association fiber tracts in alcoholism.

2160. Frontal White Matter Choline-Containing Compounds Increase with Alcohol Consumption and Glutamate Decreases with Increasing Addiction Criteria

Gabriele Ende1, Derik Hermann2, Mareen Hoerst1, Nuran Tunc-Skarka1, Gunilla Oberthuer1, Svenja Wichert2, Juri Rabinstein2, Wolfgang Weber-Fahr1, Karl Mann2, Sabine Vollstaedt-Klein2

1Neuroimaging, Central Institute of Mental Health, Mannheim, Germany; 2Addiction Medicine, Central Institute of Mental Health, Mannheim, Germany

With this 1H MRS study we aimed to investigate correlations between frontal white matter choline-containing compounds and glutamate with alcohol consumption and addictions scores in heavy drinking as well as in non-abstinent alcohol dependent patients. A positive correlation of choline-containing compounds and alcohol consumption could be replicated but the high variance could not be explained by addiction criteria (OCDS, ICD-10 and DSM IV). However, measures of addiction showed significant negative correlations with glutamate in the heavy drinking groups.

2161. Test and Retest of the Emotional Responses in Adolescents Prenatally Exposed to Cocaine

Zhihao Li1, Priya Santhanam1, Claire D. Coles2, Mary Ellen Lynch2, Stephan Hamann3, Xiaoping Hu1

1Biomedical Engineering, Emory Univ. & Georgia Tech., Atlanta, GA, United States; 2Psychiatry and behavioral Science, Emory Univ., Atlanta, GA, United States; 3Psychology, Emory Univ., Atlanta, GA, United States

The present fMRI study examined the interaction effect of prenatal cocaine exposure (PCE) and development on brain activations associated with emotional arousal, in adolescents. Comparing age 17 to 15, cortical responses elicited by negative emotional stimuli are reduced in the controls but remain roughly the same in the PCE adolescents. The present results suggest a long-term and stable PCE effect on emotional arousal regulation.

2162. Altered Cortical Thickness in Young Cannabis Abusers

Deborah Yurgelun-Todd1,2, Piotr Bogorodzki3, Melissa Lopez-Larson1,2, Robert Kurjata3, John Churchwell1, Jadwiga Rogowska4

1Brain Institute, University of Utah, Salt Lake City, UT, United States; 2VISN 19 MIRECC, Salt Lake City, UT, United States; 3Institute of Radioelectronics, Warsaw Technical University, Warsaw, Poland; 4Brain Imaging Center, McLean Hospital/Harvard Medical School, Belmont, MA, United States

It is unknown whether altered cortical thickness during adolescence is associated with marijuana (MJ) use. This investigation used cortical-surface based techniques to compare MJ using adolescents and healthy controls (HC). Eighteen adolescents with DSM-IV MJ Dependence and 18 HCs had an MRI scans using a 3T Siemens Trio scanner. Cortical reconstruction and volumetric segmentation was performed with the Freesurfer image analysis suite. Compared to HCs, MJ users had decreased cortical thickness in bilateral superior frontal cortex and bilateral and left insula. Furthermore, the average thickness of the right insula was found to negatively correlate with age of first MJ use.

2163. Perfusion Deficit to Cholinergic Challenge in Veterans with Gulf War Illness

Peiying Liu Wang1, Sina Aslan1, Xiufeng Li2, David Buhner3, Richard Briggs2, Robert Haley3, Hanzhang Lu1

1Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, United States; 2Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX, United States; 3Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, United States

A highly plausible etiology for the Gulf War Illness (GWI) is that the neural damage and cognitive deficits are associated with excessive exposure to cholinesterase-inhibiting cholinergic stimulants. Our previous SPECT study provided strong indication that cerebral blood flow of veterans with Syndrome 2 GWI has reduced responses to cholinergic challenge, compared to unaffected control veterans. The present study confirmed and extended previous findings that patients with Gulf War Illness have abnormal response to an inhibitory cholinergic challenge, physostigmine infusion, when compared to age-gender-education matched control veterans. This new technique may provide a cost-effective biomarker for characterization of Gulf war illness.

2164. Cortical GABA and Glutamate Changes in Posttraumatic Stress Disorder

Anderson Mon1,2, Thomas Neylan3, Dieter Meyerhoff1,4

1Radiology, University of California, San Francisco, San Francisco, CA, United States; 2Center for Imaging of Neurodegenerative Diseases, Veteran Administration Medical Center, San Francisco, CA; 3Psychiatry, University of California, San Francisco, San Francisco, CA, United States; 4Center for Imaging of Neurodegenerative Diseases, Veteran Administration Medical Center, San Francisco, CA, United States

We studied NAA, Glu and GABA levels in post traumatic stress disorder using magnetic resonance spectroscopy. We found lower NAA in the anterior cingulate, lower GABA in the posterior occipital cortex, and lower GABA and higher Glu in the medial temporal lobe as compared to control subjects. Metabolite levels related to PTSD symptomatology and suggest neuronal injury, perhaps associated with excitatory and inhibitory processes in cortical brain

Clinical Brain Tumor Imaging: Anatomic, MT, SWI & Perfusion MRI

Hall B Monday 14:00-16:00

2165. Potential Utility of Quantitative Magnetisation Transfer Imaging for Detection of Lesion Extent in Glioblastoma Multiforme

Gerard Thompson1,2, Sha Zhao1,2, Samantha J. Mills1,2, John R. Cain1,2, Geoff J M Parker1,2, Alan Jackson1,2

1Imaging Science and Biomedical Engineering, University of Manchester, Manchester, United Kingdom; 2Biomedical Imaging Institute, University of Manchester, Manchester, United Kingdom

Glioblastoma multiforme is an aggressive primary brain tumour, which invades preferentially along white matter tracts. Histopathological and PET evidence suggests that at the time of diagnosis, infiltrating tumour already exists at sites distant from the enhancing tumour visible on conventional anatomical MR imaging. Since MR is used to plan radiotherapy and surgery, there is concern that infiltrating tumour may be missed, and may therefore escape optimal treatment. We provide preliminary evidence in two cases that quantitative magnetisation transfer (qMT) imaging can detect changes in white matter adjacent to glioblastoma which appear otherwise normal on conventional MR imaging.

2166. Perfusion MRI Fractional Tumor Bulk Mapping: Correlation with Multiple Stereotactic Biopsies in Recurrent GBM

Leland S. Hu1,2, Seban Liu3, Dilini S. Pinnaduwage4, Kris A. Smith5, Peter Nakaji5, Amylou C. Dueck6, Todd Jensen7, Jennifer M. Eschbacher8, Joseph E. Heiserman2, John P. Karis2, Josef Debbins3, Burt G. Feuerstein9, Kathleen M. Schmainda10, Leslie C. Baxter3

1Radiology, Mayo Clinic, Arizona, Scottsdale, AZ, United States; 2Radiology, Neuroradiology Section, St. Joseph's Hospital - Barrow Neurological Institute, Phoenix, AZ, United States; 3Keller Center for Imaging Innovation, St. Joseph's Hospital - Barrow Neurological Institute, Phoenix, AZ, United States; 4Radiation Oncology, University of California - San Francisco, San Francisco, CA, United States; 5Neurosurgery, St. Joseph's Hosptial - Barrow Neurological Institute, Phoenix, AZ, United States; 6Biostatistics, Mayo Clinic, Arizona, Scottsdale, AZ, United States; 7Imaging Biometrics, LLC; 8Neuropathology, St. Joseph's Hospital - Barrow Neurological Institute, Phoenix, AZ, United States; 9Neuro-Oncology, St. Joseph's Hospital - Barrow Neurological Institute, Phoenix, AZ, United States; 10Radiology, Medical College of Wisconsin, Milwaukee, WI, United States

We present methods to calculate ‘Perfusion MRI (pMRI) fractional tumor bulk,’ which quantifies and spatially localizes areas of tumor recurrence within non-specific contrast enhanced (CE) MRI lesions. We correlate these measures with the percentage, or fraction, of tissue samples histopathologically diagnosed as tumor, in a group of recurrent Glioblastoma Multiforme (GBM) patients undergoing multiple stereotactic biopsies.

2167. Pseudo-Tumoral Response of Glioblastoma to Anti-Angiogenic Treatment Prematurely Revealed by Using Arterial Spin-Labeling (ASL) Perfusion MRI and Susceptibility Weighted Imaging (SWI).

Slim Fellah1, Yann Lefur1, Elisabeth Soulier1, Céline Boucard2, Sylviane Confort-Gouny1, Olivier Chinot2, Patrick J. Cozzone1, Jean-Philippe Ranjeva1, Virginie Callot1

1Centre de Résonance Magnétique Biologique et Médicale (CRMBM), CNRS UMR 6612, Faculté de Médecine, Marseille, France; 2Unité de Neuro-Oncologie, CHU Timone, Marseille, France

Anti-angiogenics have become part of Glioblastoma therapeutic protocol. However pseudo-response followed by a critical recurrence may be observed. Non-responders thus need to be prematurely identified. However current imaging criteria are insufficient or late, new MR markers should therefore be investigated. In this preliminary study, we used a multimodal protocol including particularly ASL and SWI, which provide vascular information. A few weeks after the beginning of the treatment, FLAIR and post-contrast T1-WI showed partial response whereas perfusion MRI and SWI demonstrated hyperperfusion and vascularization increase. The parameters derived from such sequences should thus be considered as early indicators of tumor evolution.

2168. Longitudinal Monitoring of Low-Grade Glioma Transformation: A Fully-Automatic Method Using Quantitative DSC-MRI

Kyrre E. Emblem1,2, Paulina Due-Tonnessen1,3, Inge A. Rasmussen Jr1, Atle Bjornerud2,4

1The Interventional Centre, Rikshospitalet, Oslo University Hospital, Oslo, Norway; 2Department of Medical Physics, Rikshospitalet, Oslo University Hospital, Oslo, Norway; 3Clinic for Imaging- and Intervention, Rikshospitalet, Oslo University Hospital, Oslo, Norway; 4Department of Physics, University of Oslo, Oslo, Norway

In this study, a fully-automatic method for longitudinal monitoring of low-grade glioma transformation by quantitative dynamic susceptibility contrast (DSC) MRI was evaluated and compared to conventional criteria for malignant glioma progression. Thirteen patients were imaged at least three times, with an average time between two consecutive MR exams of 283 days. Our results suggest that the fully-automatic method provides a sensitive marker for tumor progression at an early stage compared to conventional imaging criteria. Also, the quantitative tumor analysis and monitoring of baseline perfusion values in unaffected brain tissue, allows inter- and intra-patient comparisons across MR machines and institutions.

2169. Can Susceptibility-Weighted Imaging Determine Response to Combined Anti-Angiogenic, Cytotoxic, and Radiation Therapy in GBM Patients?

Janine M. Lupo1, Soonmee Cha1, Emma Essock-Burns1,2, Nicholas Butowski3, Sarah J. Nelson1,2

1Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, United States; 2Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, United States; 3Department of Neurosurgery, University of California, San Francisco, San Francisco, CA, United States

This study investigated whether the unique contrast provided by SWI, which highlights heterogeneity within the post-gadolinium contrast enhancing brain tumor lesion, can predict response to treatment. Nineteen patients with newly-diagnosed GBM were imaged prior to beginning anti-angiogenic, cytotoxic, and radiation therapy and followed until progression. The volume of SWI hypointense signal within the contrast-enhancing lesion was dramatically higher in patients who progressed after 1 year post-therapy compared to patients who progressed within 6 months of initiating treatment. These findings suggest that SWI could be advantageous for determining which patients would be the best candidates for adjuvant anti-angiogenic therapeutic strategies.

2170. Comparison of DSC-Derived Perfusion Parameters in Response to Conventional Therapy or Adjuvant Anti-Angiogenic Therapy in Patients Newly-Diagnosed with GBM

Emma Essock-Burns1,2, Yan Li1, Janine M. Lupo1, Mei-Yin Polley3, Nicholas Butowski3, Susan M. Chang3, Soonmee Cha, 1,3, Sarah J. Nelson1,4

1Department of Radiology and Biomedical Imaging, UC San Francisco, San Francisco, CA, United States; 2Joint Graduate Group in Bioengineering, UC San Francisco/UC Berkeley , San Francisco, CA, United States; 3Department of Neurological Surgery, UC San Francisco, San Francisco, CA, United States; 4Department of Bioengineering and Therapeutic Sciences, UC San Francisco, San Francisco, CA, United States

Adjuvant anti-angiogenic therapy may alter the presentation of contrast enhancement creating a clinical need for new methods of evaluating response. Dynamic susceptibility contrast enhanced imaging was used to assess vascular changes of patients newly diagnosed with GBM in response to either conventional (XRT+cytotoxic) or adjuvant anti-angiogenic therapy. A decrease in vascularization was observed early in adjuvant anti-angiogenic therapy. Progression-free survival status of patients receiving anti-angiogenic therapy may be dominated by an initial change in leakage, while PFS of patients receiving conventional therapy is not. This work highlights the need for further functional imaging techniques for the evaluation of response.

2171. Parametric Response Map as an Imaging Biomarker to Distinguish Progression from Pseudoprogression in High Grade Gliomas

Christina Tsien1, Craig J. Galban1, Thomas L. Chenevert1, Timothy D. Johnson1, Daniel A. Hamstra1, Pia C. Sundgren1, Larry Junck1, Charles R. Meyer1, Alnawaz Rehemtulla1, Theodore Lawrence1, Brian D. Ross1

1University of Michigan, Ann Arbor, MI, United States

We have developed a reliable method for distinguishing true progression from pseudoprogression by quantifying on a voxel-wise basis therapeutic-associated hemodynamic alterations in patients with high grade glioma. The parametric response map of rCBV (PRMrCBV) at week 3 during chemoradiation is shown to be a potential early imaging biomarker of response that may be helpful in distinguishing pseudoprogression from true progression in patients with high grade glioma.

2172. Quantitative Metrics Derived from DCE MRI as a Biomarker for Early Response to Radiation Therapy in Brain Metastases

Yue Cao1, Felix Y. Feng, Diana Gomez-Hassan2, James A. Hayman, Theodore S. Lawrence, Christina I. Tsien

1Radiology and Radiation Oncology, University of Michigan, Ann Arbor, MI, United States; 2Radiology, University of Michigan, Ann Arbor, MI, United States

The response of metastatic lesions to whole brain radiation therapy (WBRT) is highly heterogeneous. In this study, we evaluated quantitative metrics derived from DCE MRI for early assessment of response of brain metastatic lesions to WBRT. We found that changes in vascular volume and perfusion at the completion of WBRT differentiated responsive lesions from non-responsive ones. These DCE metrics have the potential for early prediction of treatment response in brain metastases. This requires further validation, but may provide a means for individualizing therapy in patients with brain metastases by selecting patients requiring treatment intensification with stereotactic RT.

2173. Dynamic Contrast Enhanced and Susceptibility Based CBV Measurements Perform Equally in Grading of Cerebral Gliomas

Muftah Ahmed Manita1, Paul Morgan2, Keith Robson3, Timothy Jaspan3, Dorothee P. Auer1

1Academic Radiology, University of Nottingham, Nottingham, United Kingdom; 2Radiology & Radiological Science, Medical University of South Carolina, United States; 3Nottingham University Hospital, United Kingdom

Perfusion MRI DSC (T2*) has shown added values in glioma tumour differentiation with rCBVmax is the best performing metrics obtained from dynamic susceptibility contrast technique (DSC). However, this technique is susceptible to blood leak that results in rCBV overestimation. T1 MRI perfusion (DCE) is not susceptible to vascular disruption. Nineteen patients with low and high grade glioma underwent MR perfusion (T1 and T2*) was analysed with Java image software. Significant difference (P=0.000) with excellent correlation (0.81) between the two tumour grades in both techniques with accuracy of 100%. T1 based DCE is robust technique to follow postoperative cases.

2174. Enhancing Fraction and Survival in Glioblastoma Multiforme

Samantha Jane Mills1,2, Calvin Soh2, Gerard Thompson1, Giovanni Buonaccorsi1, Catherine McBain3, Sha Zhao1, Geoff James Martin Parker1, Alan Jackson1,2

1Imaging Science and Biomedical Engineering, University of Manchester, Manchester, Greater Manchester, United Kingdom; 2Department of Neuroradiology, Salford Royal Foundation Trust Hospital, Salford, Greater Manchester, United Kingdom; 3Department of Clinical Oncology, Christie Hospital, Manchester, Greater Manchester, United Kingdom

This study describes the relationship between the DCE-MRI derived measure, Enhancing Fraction, and overall survival in patients with Glioblastoma Multiforme, with the findings of increased survival in association with elevated Enhancing Fraction.

Imaging of Brain Tumors: Techniques & Contrast Media

Hall B Tuesday 13:30-15:30

2175. Delta T1 Method: An Automatic Post-Contrast ROI Selection Technique for Brain Tumors

Devyani Bedekar1,2, Todd Jensen3, Scott Rand1,4, Mark Malkin, 2,5, Jennifer Connelly, 2,5, Kathleen Schmainda, 2,6

1Radiology, Medical College of Wisconsin, Milwaukee, WI, United States; 2Translational Brain Tumor Research Program, Medical College of Wisconsin, Milwaukee, WI, United States; 3Imaging Biometrics, Milwaukee, WI, United States; 4Translational Brain Tumor Research Program, Medical College of Wisconsin, Milwaukee, WI, United States; 5Neurology, Medical College of Wisconsin, Milwaukee, WI, United States; 6Radiology & Biophysics, Medical College of Wisconsin, Milwaukee, WI, United States

The primary approach to monitoring patients with brain tumors is to obtain pre and post-contrast T1-weighted images. Bright areas on the pre-contrast images are suggestive of blood products, which may be a result or treatment, and are therefore not to be considered as enhancing lesions on the post-contrast images. However, the difference between the brightness that exists on both the post and pre-contrast images can be quite subtle, a condition that is occurring more frequently now with the increasing use of anti-angiogenic agents. Therefore it is becoming increasingly difficult to monitor patients with brain tumors simply by visually comparing differences in enhancement. As a solution in this report we propose an automatic method, the delta T1 method (dTM), which is capable of detecting even subtle enhancing tumor free of blood products, thereby enabling the automatic creation of ROIs in a fast and reliable manner that avoids subjective variability.

2176. Analysis of Brain Tumors and Metastases by Quantitative MT Imaging with BSSFP: Initial Experiences

Meritxell Garcia1, Monika Gloor2, Christoph Stippich1, Felix Jax1, Klaus Scheffler2, Oliver Bieri2

1Department of Neuroradiology, University of Basel Hospital, Basel, Switzerland; 2Radiological Physics, University of Basel Hospital, Basel, Switzerland

The efficacy of quantitative MT (qMT) imaging for characterization of benign and malignant brain lesions is analyzed with balanced steady-state free precession. Eleven patients with 3 different lesions (4 glioblastoma multiforme, 4 meningeomas and 3 metastases) were investigated on a clinical 1.5T MR-scanner. MT-effects are described in terms of MTR, relaxation times (T1, T2), MT exchange rate (kf) and the macromolecular content (F). Marked divergences between contrast-enhancing regions, edema and normal-appearing brain were found within and between the different lesions, which might be attributed to differences in edema, cell infiltration and myelin properties. Thus, qMT-imaging might play a major role in adding information for diagnostic tumor characterization.

2177. Magnetic Resonance Imaging Contrast of Brain Tumors at 7 Tesla Compared to 3 Tesla

Iris-Melanie Noebauer-Huhmann1, Pavol Szomolanyi1,2, Claudia Kronnerwetter1, Siegfried Trattnig1

1MR Centre - High field MR, Department of Radiology, Medical University of Vienna, Vienna, Austria; 2Department of Imaging Methods, Institute of Measurement Science, Slovak Academy of Sciences, Bratislava, Slovakia

It is well known that the effect of MR contrast agents is influenced by the magnetic field strength. The aim of the study was to compare the diagnostic efficacy of a Gadolinium-based MRI contrast agent (gadobenate dimeglumine) in primary brain tumors at 7Tesla versus 3Tesla. Post contrast MP-RAGE sequences were evaluated by region of interest measurements. At 7Tesla, the tumor-to-brain-contrast after gadolinium administration was significantly higher (91.4) than at 3Tesla (37.3). Further studies will show if the higher tumor-to-brain-contrast post gadolinium administration at 7Tesla may be beneficial for tumors with minor contrast agent accumulation, or allow for a dose reduction.

2178. Ultra-High Field MRI of Primary Brain Tumors: Contrast and Resolution

Fernando Emilio Boada1, Yongxian Qian1, Frank Lieberman2, Denise Davis1, Ronald Hamilton3

1MR Research Center, University of Pittsburgh, Pittsburgh, PA, United States; 2Neurooncology, University of Pittsburgh, Pittsburgh, PA, United States; 3Department of Neuropathology, University of Pittsburgh, Pittsburgh, PA, United States

Imaging of primary brain tumors at Ultra-High Field (UHF) magnetic resonance imaging (MRI) has tremendous appeal due to the expected improvements in contrast at spatial resolution scales previously unpractical for in vivo human MRI. In this work we demonstrate the use of UHF for evaluating the microvascular structure of brain tumors and the improvements in signal quantification during sodium MRI

2179. Combined 31P and 1H Magnetic Resonance Spectroscopic Imaging of Phosphomono and -Diesters in Human Brain Tumors at 3T.

Jannie Petra Wijnen1, Tom W.J. Scheenen1, Arend Heerschap1

1Radiology, Radboud University Nijmegen Medical Centre, Nijmegen, Gelderland, Netherlands

We demonstrated the clinical feasibility of combined 1H and 31P MRSI with sensitivity enhancement by polarisation transfer of 1H to 31P spins of human brain tumours at 3T to uncover the composition of (phosphorylated)choline and phosphorylated ethanolamine compounds in the membrane. Preliminary results from 4 patients with different tumour types show potentially important differences among tumours. This opens a window on a detailed view of the levels of some key metabolites in membrane phospholipid metabolism of human tumours.

2180. Multi-Echo Time Approach for Study of Metabolic Profiles in Brain Tumors at 3T

Changho Choi1, Ivan Dimitrov1,2, Deborah Douglas1, Aditya Patel1, Hao Huang1, Ralph Deberardinis3, Juan Pascual4, Robert Bachoo5, Craig Malloy1, Elizabeth Maher6

1Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, United States; 2Philips Medical Systems, Cleveland, OH, United States; 3Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, United States; 4Neurology, Physiology and Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, United States; 5Neurology, University of Texas Southwestern Medical Center, Dallas, TX, United States; 6Internal Medicine and Neurology, University of Texas Southwestern Medical Center, Dallas, TX, United States

Echo time dependence of coupled-spin metabolites following point-resolved spectroscopy (PRESS) at 3T has been investigated with computer simulations. Three pairs of PRESS subecho times, (TE1, TE2) = (32, 22), (32, 80), and (32, 214) ms, were selected for optimum selectivity of glutamate and glutamine, and used for in vivo measurements of metabolites in brain tumors. We present preliminary in vivo results that show pronounced abnormalities of metabolic profiles, including elevated glutamine and glycine in glioblastoma multiforme and differentiation between lipids and lactate in low- and high-grade gliomas.

2181. In Vivo MRI of MR-Labeled Neural Stem Cell Migration to Gliomas

Bensheng Qiu1, Daohai Xie2, Piotr Walczak3, Xubin Li, Jesus Ruiz-Cabello3, Satoshi Minoshima, Jeff W.M. Bulte3, Xiaoming Yang

1University of Washington, Seattle, WA, United States; 2Radiology, Suzhou University School of Medicine; 3The Johns Hopkins University

Neural stem cells (NSC) have been recognized as cellular vehicles for treatment of invasive brain tumors. MRI is a unique non-invasive tool to monitor the migration of stem cells labeled with MR contrast agents, such as superparamagnetic iron oxide (SPIO) particles. Pervious studies have confirmed that magnetosonoporation (MSP) can instantly labeled SPIO into stem cells. The aim of this study was to validate the feasibility of MRI of MSP-labeled NSC migration to gliomas in vivo.

2182. The Effect of Fiber Affinity on Predicted Cancer Cell Migration Based on MR-DTI

Anitha Priya Krishnan1, Delphine Davis2,3, Paul Okunieff3, Walter G. O'Dell, 1,3

1Biomedical Engineering, University of Rochester, Rochester, NY, United States; 2Imaging Sciences, University of Rochester, Rochester, NY, United States; 3Radiation Oncology, University of Rochester, Rochester, NY, United States

The current methods for determining the treatment margin for Stereotactic Radiotherapy of gliomas are inadequate as recurrences often occur at the boundary of the treatment margin. We developed a random walk model to determine the microscopic spread of tumor cells to facilitate in the development of anisotropic treatment margins. In this study we have shown that the affinity of cancer cells to fibers in the brain can be modeled better by the spread in the direction of migration about the Principal Diffusion Direction determined using DTI than by using a variable step-size in the random walk of cancer cells.

2183. Correlating DTI-Based Cancer Cell Migration Model Predictions with the Location of Secondary Tumors

Anitha Priya Krishnan1, Delphine Davis2, Paul Okunieff3, Walter G. O'Dell3

1Biomedical Engineering, University of Rochester, Rochester, NY, United States; 2Imaging Sciences, University of Rochester, Rochester, NY, United States; 3Radiation Oncology, University of Rochester, Rochester, NY, United States

The current methods for determining the treatment margins for stereotactic radiotherapy of gliomas is inadequate as the tumor often recurs at the boundary of the treatment margin. The areas of high normalized cell migration predicted by our random walk model coincide with the direction along which the tumor recurs. Here we have established that there is a statistically significant correlation between the model predictions and the recurrence site and the average normalized cell concentration in the recurrence site is higher than the normalized cell concentration in 78% of the voxels on a surface equidistant from the primary tumor surface.

2184. Decreased Cerebral Oxygen Extraction Fraction (OEF) Measured by MR QBOLD Following Stereotactic Radiosurgery (SRS) in Patients with Metastatic Brain Tumors

Parinaz Massoumazdeh1, Xiang He1, Sarah Jost2, Keith Rich3, Dmitriy Yablonskiy1, Tammie Benzinger4

1Mallinckrodt Institute of Radiology, Washington University in Saint Louis; 2Swedish Hospital, Seattle, WA, United States; 3Neurosurgery, Washington University in Saint Louis; 4Mallinckrodt Institute of Radiology, Washington University in Saint Louis, St. Louis, MO, United States

There is growing evidence that solid organ tumors with ability to grow in hypoxic conditions demonstrate resistance to conventional chemotherapy and radiation therapy. Here, we used MR qBOLD technique to measure the OEF of metastatic brain tumors before and after SRS. In this population, OEF of both the tumors and peritumoral edema prior to SRS was elevated. Following SRS, OEF decreased in the areas of lesions. This suggests that qBOLD OEF may provide a new method to monitor brain tumor response to therapy.

2185. A Comparison of Signal Intensity & DCE-MRI Based Methods for Assessing Enhancing Fraction

Samantha Jane Mills1,2, Gerard Thompson1, Giovanni Buonacorrsi1, Geoff James Parker1, Alan Jackson1,2

1Imaging Science and Biomedical Engineering, University of Manchester, Manchester, United Kingdom; 2Department of Neuroradiology, Salford Royal Foundation Trust Hospital, Salford, Greater Manchester, United Kingdom

The established technique for measuring Enhancing Fraction utilises the initial area under the concentration curve derived from a DCE-MRI acquisition. This can be time consuming and requires complex post processing analysis. This study examines the feasibility of obtaining an measure of Enhancing Fraction from conventional, pre and post contrast T1weighted imaging and compares this to the established DCE-MRI derived technique. The two methods show good correlation but are not directly interchangeable methods of measuring Enhancing Fraction.

2186. Simultaneous Resting State FMRI and FET-PET

Irene Neuner1,2, Joachim Bernhard Maria Kaffanke1, Cornelius Werner1,2, Martina Reske1,3, Karl-Joseph Langen1, Hans Herzog1, N. Jon Shah1,2

1Institute of Neurosciences and Medicine 4, Medical Imaging Physics, Forschungszentrum Jülich GmbH, 52425 Juelich, Germany; 2Faculty of Medicine, Department of Neurology, RWTH Aachen University, 52074 Aachen, Germany; 3Department of Psychiatry, University of California San Diego, San Diego, CA, United States

For the planning of surgical intervention in human brain tumour cases, it is important to know if critical brain areas might be affected by the surgical process itself. PET imaging using radiolabelled amino acids is a valuable technique for the diagnosis of cerebral gliomas. O-(2-[18F]Fluorethyl)-L-Tyrosin (FET) is a well established amino acid tracer that delivers information about tumour extent, the optimal biopsy site and detection of tumour recurrences. In this study, FET-PET and BOLD-fMRI data were acquired simultaneously; data from a representative human brain tumour case are presented. In contrast to task-based functional studies, resting state fMRI offers the opportunity to detect a variety of cortical networks in a single experiment.

2187. Multi-Layer Appearance of Abscess Capsule on Post-Gd SWI Images: Effects of Filtering and Phase Mask

Ping-Hong Lai1,2, Hing-Chiu Chang3,4, Hsiao-Wen Chung4

1Department of Radiology, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan; 2School of Medicine, National Yang-Ming University, Taipei, Taiwan; 3Applied Science Laboratory, GE Healthcare Taiwan, Taipei, Taiwan; 4Institute of Biomedical Electronics and Bioinformatics, National Taiwan University, Taipei, Taiwan

SWI is a novel MR technique that exploits the magnetic susceptibility differences of various tissues, such as venous structure and iron deposition. When SWI was applied to patients with abscess, we found that, compared with homogeneous rim-enhancement on post-contrast magnitude images, the capsular portion of pyogenic brain abscess on post-contrast SWI images showed a multi-layer appearance. In this work, in order to clarify whether this multi-layer characteristic is physiological or technical in it origin, we investigate the causes of this multi-layer appearance, and use a theoretical model to simulate the multi-layer appearance upon the use of different SWI processing parameters.

2188. When Does Brain Motion Interfere with the Accuracy of Stereotactic Radiosurgery? Investigation of Brain Motion in the Presence of Stereotactic Frame.

Dee H. Wu1, Jesse Hatfield1, Jignesh Modi1, Genu Mathew1

1Radiological Sciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States

The aim of stereotactic radiosurgery is to provide accurate placement of radiation localized to targeted diseased tissues while minimizing placement of large doses of radiation into sensitive normal tissues (such as motor strip, brain stem, internal capsule, optic nerve, and other major nerve bundles). It is well known that the brain moves during the cardiac cycle in which the action of pulsatile blood flow produces brain expansion and contraction. Such movement provides a potential conflict with the objective of providing millimeter to submillimeter localization accuracy of radiation treatment. This has led to recommendations for the use of electronic gating of radiosurgery placement. While brain motion was extensively studied in the early 1990s(1, 2), and has been a source of debate for more recent studies for the degree of head fixation required for patients for presurgical planning with fMRI (3). Such brain motion has been cited to be on the order of 0.5 mm for controlled studies over a short period of time (minutes), to 1-3 millimeters over the course of an fMRI experiment when standard to minimal head fixation is used (4). None of these studies were performed with such stringent fixation as that provided during radiotherapy. The frames such that include head fixation with the insertion of metal pins attached to the patient skull with metallic frames.

2189. Image-Guided Tissue Validation of Combined Preload Dosing and Mathematical Modeling Correction of Perfusion MRI Measures

Leland S. Hu1,2, Leslie C. Baxter3, Dilini S. Pinnaduwage4, Todd Jensen5, Amylou C. Dueck6, Jennifer M. Eschbacher7, Joseph E. Heiserman2, John P. Karis2, Josef Debbins3, Jonathan Placencia Placencia8, Seban Liu3, Burt G. Feuerstein9, Kathleen M. Schmainda10

1Radiology, Mayo Clinic, Arizona, Scottsdale, AZ, United States; 2Radiology, Neuroradiology Section, St. Joseph's Hospital - Barrow Neurological Institute, Phoenix, AZ, United States; 3Keller Center for Imaging Innovation, St. Joseph's Hospital - Barrow Neurological Institute, Phoenix, AZ, United States; 4Radiation Oncology, University of California - San Francisco, San Francisco, CA, United States; 5Imaging Biometrics, LLC; 6Biostatistics, Mayo Clinic, Arizona, Scottsdale, AZ, United States; 7Neuropathology, St. Joseph's Hospital - Barrow Neurological Institute, Phoenix, AZ, United States; 8Biomedical Engineering, Arizona State University, Tempe, AZ, United States; 9Neuro-Oncology, St. Joseph's Hospital - Barrow Neurological Institute, Phoenix, AZ, United States; 10Radiology, Medical College of Wisconsin, Milwaukee, WI, United States

We validate mathematical modeling correction of relative cerebral blood volume (rCBV) in regards to effectiveness of 1) minimizing T1W leakage and 2) correcting T2/T2*W residual effects, by correlating localized measures with image-guided tissue histopathology and microvascular density from stereotactic biopsies in post-treatment high-grade gliomas.

2190. Automatic Segmentation of Optic Pathway Gliomas Using Multiparametric Mri Methods

Liat Ben Sira1, Lior Weizman2, Leo Joskowicz2, Ronit Precel1, Shlomi Constantini3,4, Dafna Ben Bashat5

1Department of Radiology , Tel Aviv Sourasky Medical Center, Tel-Aviv, Israel; 2School of Eng and Computer Science, The Hebrew Univeristy of Jerusalem, Jerusalem, Israel; 3The Paediatric Neurosurgery Department, Tel Aviv Sourasky Medical Center, Tel-Aviv, Israel; 4Sackler Faculty of Medicine, Tel Aviv University, Tel-Aviv, Israel; 5The Wohl Institute for Advanced Imaging, Brain Imaging Center, Tel Aviv Sourasky Medical Center , Tel-Aviv, Israel

Accurate and consistent volumetric measurements of optic pathway gliomas (OPG), the most common tumor in the brain in patients with Neurofibromatosis, are clinically crucial. In this study we present an automatic method for segmentation of OPGs from multi-spectral MRI datasets. The method effectively incorporates prior location of the OPG, its shape and intensity and accurately identifies the boundaries in a consistent and repeatable manner. The method was tested on 15 data sets, the optimal threshold was derived from a receiver operating characteristic curve, and a significant correlation was obtained between the volume calculated using this method compared to manual measurements.

2191. Translational Methods for Retrospective Long Term Evaluation of Cancer with MRS

Dee H. Wu1, Levi Garrett1, Jignesh Modi1, Bowei Han1, Hans Cao1

1Radiological Center, University of Oklahoma Health Sciences Center, Edmond, OK, United States

We have created a procedure for retrospective review of digitized MRS images that permits fundamental baseline removal and frequency bracketing with the target of creating a user-friendly tool. This newly created clinical workflow will improve long term care for patients that may require important decisions pertaining to whether the status of a tumor has changed (such as tumor reoccurrence or remission). A central concept is that we have also conducted tolerance testing in which common confounds to artifacts that arise from shimming, electronic noise, field inhomogenity, coil sensitivities, relaxation.

2192. MR Biomarkers of Tyrosine Kinase Inhibition in Mouse Gliomas

Paul A. Schornack1, Jia-Jean Yiin, Bo Hu, Raghvendra S. Sengar, Ken-Wei Liu, Haizhong Feng, Frank S. Lieberman, Jann N. Sarkaria2, Erik Wiener, Hsin-I Ma3, Shi-yuan Cheng

1Radiology, University of Pittsburgh, Pittsburgh, PA, United States; 2Mayo Clinic; 3Taiwan National Defense Medical Center

We present a comparison of MR techniques sensitive to T2, T2*, & ADC to measure mouse gliomas & correlate with histology. We compare untreated mice with mice treated with an anti-angiogenic agent, ZD6474 (Zactima, vandetanib), a dual inhibitor of VEGFR2 & EG. ZD6474 significantly inhibited growth & angiogenesis of gliomas expressing EGFRvIII by specifically blocking signaling transducers in brain, which suggests a potential application in treatments for gliomas that overexpress this factor. Our results indicate that susceptibility/T2* weighted MR along with ADC and T2 measurements can be used as a means of non-invasively quantifying the efficacy of such treatment protocols.

2193. Characterization of Brain Tumor Using High Order Diffusion Imaging

Chu-Yu Lee1, Chris Goettl2, Leslie C. Baxter3, John P. Karis3, Josef P. Debbins, 1,3

1Electrical Engineering, Arizona State University, Tempe, AZ, United States; 2College of Medicine, University of Arizona, Phoenix; 3Barrow Neurological Institute, Phoenix

Brain neoplasms are typically characterized by contrast enhanced T1 imaging. Depending on the course of treatment, tumor reoccurrence remains a possibility, and can be difficult to distinguish from other enhancing areas, for example post-treatment radiation effects (PTRE), typically necrosis [1]. Further, detailed information about the tumor heterogeneity as detected by standard MR methods is not generally available, but can play a significant role in characterizing and grading the tumor. In this work, a simple multi-b-value DWI sequence has been developed to better understand the heterogeneity and diffusion characteristics of different types of tumors, encountered during routine clinical scanning. The signal decay is fitted with two recently developed diffusion models: a stretched exponential (£\-DWI) [2] and a cumulant expansion (DKI) [3] model, where fitted parameters £\ and Kapp were shown to correlate the diffusion heterogeneity. We expected to see differences in alpha and K when the multi-b-value DWI sequence directed to the anatomy of interest, primarily due the heterogeneity of the more advanced tumors.

2194. Tumor Enhancement in a Brain Glioma Model: An Intra-Individual Comparison of Half Dose Gadobenate Dimeglumine Vs Full Dose Gadopentetate Dimeglumine at 1.5 and 3 T

Ulrike I. Attenberger1, Val M. Runge2, Jonathan Williams3, Henrik J. Michaely

1Department of Clinical Radiology and Nuclear Medicine, University Medical Center Manheim, Germany, Mannheim, Baden-Württemberg, Germany; 2Scott & White Clinic and Hospital, Texas A&M University Health Science Center, Department of Radiology , Temple, TX, United States; 3Department of Radiology, , Scott & White Clinic and Hospital, Texas A&M University Health Science Center, Temple, TX, United States

Regarding nephrogenic systemic fibrosis (NSF), the injected dose level becomes very important, since NSF is reported to be related to gadolinium chelate injection in patients with an impaired renal function, depending upon chelate stability and dose. With gadobenate dimeglumine, a chelate with transient protein binding and a higher r1 relaxivity became available. Combining a high relaxivity chelate and 3 T offers multiple opportunities for dose reduction without loss in image quality. This was proven in a rat brain glioma model at 1.5 and 3 T, comparing half dose gadobenate dimeglumine vs full dose gadopentetate dimeglumine, a standard extracellular gadolinium chelate.

2195. MRI Acceptance Protocol for the Multicenter GO Glioblastoma Project

Sylvain Ollivro1,2, Pierre Antoine Eliat3, Eric Hitti, 2,3, Loan Tran1, Jacques Donald de Certaines1,4, Hervé Saint-Jalmes2,4

1Cancéropôle Grand Ouest, Rennes, France; 2LTSI, INSERM, U642, Université Rennes 1, Rennes, France; 3PRISM, IFR 140/Biogenouest, Université Rennes 1, Rennes, France; 4CRLCC, Rennes, France

We have verified thanks to a specific common quality control that 7 MRI devices included in a multicenter clinical project, had homogenous and acceptable characteristics to allow quantification and comparison between parameters extracted from different patient images acquired on different sites and to permit correlation with biopsies. This quality control was established with sequences from the MRI protocol. The studied parameters slightly varied depending on the different sites and MRI manufacturers and were in the awaiting of the project. This kind of quality control procedure should be included at the early beginning of any multicenter clinical projects involving quantitative MRI.

2196. Large Scale Comparison of Gadobenate Dimeglumine and Comparator Agents

Matthew J. Kuhn1, Howard A. Rowley2, Michael V. Knopp3, Kenneth R. Maravilla4, Zoran Rumboldt5

1Radiology, University of Illinois at Peoria, Peoria, IL, United States; 2Radiology, University of Wisconsin, Madison, WI, United States; 3Radiology, Ohio State University, Columbus, OH, United States; 4Radiology and Surgery, University of Washington, Seattle, WA, United States; 5Radiology, Medical University of South Carolina, Charleston, SC, United States

382 patients were randomized to receive 2 MR exams within 2 days to 2 weeks with equal 0.1mmo/kg doses of either gadobenate dimeglumine (N=382) or a comparator gadolinium agent. Blinded experts assessed post-contrast images for both qualitative (eg, global contrast enhancement, lesion-to-brain contrast, lesion delineation, internal lesion morphology and structure, tumor vascularization, and global image preference) and quantitative (eg, contrast-to-noise ratio [CNR]; percent lesion enhancement) efficacy parameters. In all six studies, images produced following administration of Gd-BOPTA demonstrated greater contrast enhancement, provided more diagnostic information including additional lesion detection, and were significantly preferred by experienced, blinded neuroradiologists.

Brain Tumor Imaging: Diffusion, MRS & High-Field Imaging

Hall B Wednesday 13:30-15:30

2197. Assessment of Invasion and Recurrence in Glioblastoma Multiforme Using Diffusion Weighted MRI Edge Characteristics of Contrast Enhancing Tumor

Peter Sherman LaViolette1,2, Benjamin M. Ellingson, 2,3, Jennifer M. Connelly, 2,4, Mark G. Malkin, 2,4, Scott D. Rand, 2,3, Kathleen M. Schmainda1,2

1Biophysics, Medical College of Wisconsin, Milwaukee, WI, United States; 2Translational Brain Tumor Program, Medical College of Wisconsin, Milwaukee, WI, United States; 3Radiology, Medical College of Wisconsin, Milwaukee, WI, United States; 4Neurology, Medical College of Wisconsin, Milwaukee, WI, United States

Traditionally, brain tumor recurrence is defined as new MRI contrast enhancement apparent in follow-up imaging. This study shows that diffusion weighted MRI edge characteristics of contrast enhancing tumors show measurable differences indicative of tumor invasion prior to contrast enhancing recurrence

2198. Determination of Structural Differences Between Glioblastomas and Metastases by Diffusion Kurtosis Imaging

Peter Raab1,2, Elke Hattingen2, Kea Franz3, Friedhelm E. Zanella2, Heinrich Lanfermann1,2

1Neuroradiology, Hannover Medical School, Hannover, Germany; 2Neuroradiology, JW Goethe University, Frankfurt/Main, Germany; 3Neurosurgery, JW Goethe University, Frankfurt/Main, Germany

Diffusion kurtosis imaging evaluates the non-Gaussian diffusion pattern of water and indicates tissue structure complexity. In this diffusion study we found differences between glioblastomas and cerebral metastases, that indicate more directed diffusion in glioblastomas and a higher structural complexity in metastases.

2199. Fiber Density Mapping in Patients with Gliomas: Histopathologic Evaluation of a Novel Approach for Post-Processing of DTI Data

Andreas Stadlbauer1,2, Michael Buchfelder2, Oliver Ganslandt2

1MR Physics Group, Department of Radiology, Landesklinikum St. Poelten, St. Poelten, Austria; 2Department of Neurosurgery, University of Erlangen-Nuremberg, Erlangen, Germany

To histopathological evaluate fiber density mapping (FDM) in glioma patients for assessment of the extent of destruction of white matter structures in the center, the transition zone and the border zone of gliomas. We correlated FDM-data and histopathological findings from 78 stereotactic biopsies of 20 glioma patients. We found a negative logarithmic correlation of fiber-density with both, % tumor infiltration and tumor cell number. For a tumor infiltration of >60% no fibers are remaining. In tumor regions with 0.7). There were statistically significant correlations between the DTI indices and several ISNCSCI clinical impairment scores.

2452. Reduced Field of View Imaging for Twice-Refocused Diffusion EPI Using a Perpendicular Refocusing Slab

Rafael Luis O'Halloran1, Samantha J. Holdsworth1, Stefan Skare1, Roland Bammer1

1Department of Radiology, Stanford University, Stanford, CA, United States

A simple method for reducing the phase field of view in twice-refocused DTI EPI is presented and compared with full of view imaging in DTI of the upper spine. The 180-degree refocusing slice select pulses are played out on the phase encoding axis instead of the slice-encoding axis. This allows the phase field of view to be reduced to the width of the perpendicular refocusing slab without introducing wrap. Results show that the reduced field of view method produces diffusion weighted images of the cervical and thoracic spine that are less distorted than those of standard full field of view EPI for the same scan time.

2453. Spinal Cord Diffusion Tensor Imaging (DTI) and 1H-MR Spectroscopy (MRS) at 1.5T and 3T.

Virginie Callot1, Yann Le Fur1, Jean-Philippe Ranjeva1, Guillaume Duhamel1, Patrick J. Cozzone1

1Centre de Résonance Magnétique Biologique et Médicale (CRMBM), CNRS, UMR 6612, Faculté de Médecine, Marseille, France

Diffusion Tensor Imaging (DTI) and single-voxel 1H-MR spectroscopy (MRS) of the spinal cord (SC) are challenged by several difficulties, including strong magnetic field inhomogeneities, respiratory and cardiac movements, and small size of the spinal cord. Whereas several studies have shown promising results, there is scant literature comparing 1.5T and 3T MRI and MRS. In this abstract, we investigate the efficiency of the available manufacturer MRS and DTI sequences, in terms of image/spectra quality and metrics, at both 1.5T and 3T, for different spinal cord locations (thoracic and cervical levels) and for different imaging plane orientations (sagittal and axial).

2454. Diffusion Tensor MR Imaging of the Healthy Human Cervical, Thoracic and Lumbar Spinal Cord

Rachael Lee Bosma1, Christopher Alan Kidd1, Patrick W. Stroman1,2

1Centre for Neuroscience Studies, Queen's University, Kingston, Ontario, Canada; 2Departments of Diagnostic Radiology and Physics, Queen's University, Kingston, Ontario, Canada

A greater understanding of diffusion indices within the healthy spinal cord is necessary for comparison with clinical populations. Here we measured fractional anisotropy and apparent diffusion coefficient values for cervical (C2-C7), thoracic (T3-T8) and lumbar (T10-L1) regions of the cord. FA vs. ADC values were plotted and three clusters were determined using a k-means partition to characterize each region of the spinal cord. DTI indices in the healthy cord were observed to be relatively consistent across regions, indicating that changes in these indices as a result of trauma at any level can be characterized relative to these observed indices.

2455. Diffusion Tensor MR Characteristics of Cervical Spondylosis

Benjamin M. Ellingson1,2, Jean-Louis Benae2, Shekar N. Kurpad2, Brian D. Schmit3, Mehmet Kocak1, Marjorie C. Wang2

1Dept. of Radiology, Medical College of Wisconsin, Milwaukee, WI, United States; 2Dept. of Neurosurgery, Medical College of Wisconsin, Milwaukee, WI, United States; 3Dept. of Biomedical Engineering, Marquette University, Milwaukee, WI, United States

The objective of the current study was to characterize the diffusion tensor MRI (DTI) properties of the cervical spinal cord in patients diagnosed with cervical spondylosis. Axial DTI was performed throughout the region of highest cord compression in 17 patients with cervical spondylosis using a clinical 1.5T MRI system. Results showed spatially localized regions of high FA and low MD at the site of compression. Longitudinal ADC was significantly lower than historic controls, whereas transverse ADC was significantly higher than historic controls in regions adjacent to the site of compression. Results from this study suggest that FA and MD can be used to localize regions of the spinal cord under the largest degree of compression.

2456. Pitfalls of Spinal DTI in Cervical Spondylotic Myelopathy

Enedino Hernandez Torres1,2, Alex L. MacKay2,3, Erin MacMillan4, Teodoro Cordova Fraga1, Alonso Ramirez Manzanares5, Armin Curt6, David Li2, Burkhard Mädler7, M Dvorak8

1Division de Ciencias e Ingenierias, Universidad de Guanajuato, Leon, Guanajuato, Mexico; 2Radiology, University of British Columbia, Canada, Vancouver, Brithish Columbia, Canada; 3Physics & Astronomy, University of British Columbia, Canada, Vancouver, Brithish Columbia, Canada; 4Clinical Research, University of Bern; 5Facultad de Matematicas, Universidad de Guanajuato, Guanajuato, Mexico; 6Spinal Cord Injury Center, University of Zurich; 7Philips Healthcare, Vancouver, Brithish Columbia; 8International Collaboration on Repair Discoveries

Diffusion measures have proved to be useful in cervical spondylotic myelopathy (CSM). This study compared two methods of analysis for spinal DTI in CSM subjects and normals. The first approach defined the spine area on the basis of a fractional anisotropy threshold of 0.3; the second employed a threshold based upon eigenvector orientation within 45 degrees of the direction of the spine. The two approaches yielded markedly different diffusion measures in controls, in stenotic regions and in non-stenotic regions. Further examination revealed that the eigenvector orientation approach included signal from CSF and hence gave artifactual results.

2457. Optimization of Reduced Field of View (RFoV) Quantitative Diffusion MRI in Thoracic Spine

David Michael Thomasson1, Leor Zach2, Laura Elizabeth Danielian3, Peter Guion2, Yuxi Pang4, Dimitrios Alexopoulos1, Nicholas John Patronas1

1Radiology and Imaging Sciences, National Institutes of Health, Bethesda, MD, United States; 2Radiation Oncology Branch, National Cancer Institute, Bethesda, MD, United States; 3EMG Section, National Institute of Neurological Disorders and Stroke, Bethesda, MD, United States; 4BU - MR, Philips Healthcare, Cleveland, OH, United States

Reduced Field of View rFoV diffusion weighted imaging techniques improve quantitative ADC and FA data for sagittal acquired thoracic spine imaging at 3Tesla relative to 1.5T. While lower field has less distortions limiting the necessity of such techniques, the reduced SNR at 1.5T makes them less desirable using clinically acceptable scan times. Here we optimize the rFoV technique in thoracic spine to obtain the best possible data in a clinical population.

2458. Toward Reproducible Tract-Specific in Vivo Diffusion Quantification in Human Cervical Spinal Cord

Junqian Xu1, Eric C. Klawiter1, Joshua S. Shimony2, Abraham Z. Snyder, 12, Robert T. Naismith1, Agus Priatna3, Tammie Benzinger2, Anne Cross1, Sheng-Kwei Song2

1Neurology, Washington University in St. Louis, St. Louis, MO, United States; 2Radiology, Washington University in St. Louis, St. Louis, MO, United States; 3Siemens Medical Solution, United States

We describe a reproducible in vivo human cervical spinal cord diffusion tensor imaging (DTI) protocol at 3T. The data acquisition and analysis procedures are described with examples from healthy (n = 17) and pathological human spinal (n = 2) cords. The described comprehensive approach (1) accounts for the natural curvature of the human spinal cord by covering C1-6 with separate tiltable slices/groups, (2) minimizes distortion and signal drop-out by localized shimming, (3) improves the robustness by motion-correction and motion-based outlier rejection, (4) corrects negative eigenvalues by non-negative non-linear DTI calculation, and (5) employs objective geometry based region-of-interest selection for tract identification.

2459. Stimulus Site and Modality Dependence of Functional Activity Within the Human Spinal Cord

Yazhuo Kong1, Michael Lee2, Catherine Warnaby1, Vishwani Wanigasekera1, Mark Jenkinson1, Irene Tracey1, Jonathan Brooks1

1FMRIB centre, Department of Clinical Neurology, University of Oxford, Oxford, Oxfordshire, United Kingdom; 2Division of Anaesthesia, University of Cambridge, Cambridge, United Kingdom

Chronic pain is thought to arise due to maladaptive changes occurring at the level of the spinal cord. To investigate such changes in humans, a non-invasive neuroimaging technique is desirable. We have investigated the functional response in the spinal cord of 18 healthy subjects to noxious stimulation using punctate and thermal stimulation of the left and right arms. Group analysis, revealed distinct regions of activity within the spinal cord that were dependent on both the side of stimulation and the type of stimulus used. These results present the first non-invasive evidence for a lateralised and stimulus-specific spinal cord response.

2460. Quantitative Magnetization Transfer Imaging of Human Cervical Spinal Cord at 3T

Richard D. Dortch1,2, E B. Welch2,3, John C. Gore1,2, Seth A. Smith1,2

1Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, United States; 2Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States; 3MR Clinical Science, Philips Healthcare, Cleveland, OH, United States

The goal of this study was to determine the feasibility of performing quantitative magnetization transfer (qMT) at high resolution in the spinal cord on clinical 3T systems. While MT imaging has been used to assess brain tissue microstructure, similar studies in the spinal cord have been limited due to high resolution demands and motion. Presumably, spinal cord qMT studies would benefit from the increased SNR at 3T; however, such studies are limited by SAR constraints. To address these issues, we developed a high resolution qMT imaging protocol of the cervical spinal cord at 3T and acquired data in healthy subjects.

2461. Fast Simultaneous Acquisition of High-Resolution Brain and Cervical Spinal Cord T1w Images to Measure Spinal Cord Atrophy: Methods and Validation

Patrick Anton Bruno Freund1,2, Catherine Dalton3, Claudia Angela Michela Wheeler-Kingshott3, Janice Glensman1, David Bradbury1, Alan James Thompson2, Nikolaus Weiskopf1

1Wellcome Trust Centre for Neuroimaging, UCL Institue of Neurology, London, United Kingdom; 2Brain Repair and Rehabilitation, UCL Institue of Neurology, London, United Kingdom; 3Neuroinflammation, UCL Institue of Neurology, London, United Kingdom

We have developed and validated a method for fast, simultaneous and high-quality imaging of the brain and cervical spinal cord (< 14 mins., 1 mm isotropic resolution) with the potential to detect, besides volumetric changes at cortical level, also changes at cervical level. It is based on a 3D MDEFT scan using an 8-channel receive head coil. Measures of cross sectional cord area, obtained with the MDEFT-based method, are in good agreement with the established standard based on 3D MPRAGE scans with dedicated spine coils, as determined in a group of healthy controls and subjects with traumatic cervical spinal cord injury.

2462. Magnetic Resonance Spectroscopy of the Cervical Spine in ALS and Pre-Symptomatic SOD1 Positive People

John D. Carew1,2, Govind Nair3, Sharon Usher4, Xiaoping P. Hu3, Michael Benatar4

1Carolinas HealthCare System, Charlotte, NC, United States; 2Biostatistics and Bioinformatics, Emory University, Atlanta, GA; 3Biomedical Engineering, Emory University; 4Neurology, Emory University

We studied MRS in the cervical spinal cord of amyotrophic lateral sclerosis (ALS) patients, healthy controls, and people with a mutation in the SOD1 gene. Single voxel PRESS/CHESS MRS was used to measure NAA, choline, creatine, and myo-inositol. We found metabolic changes in both ALS and people positive for the SOD1 mutation. Among ALS patients, metabolite ratios correlate with clinical measures of disease severity. The findings in the SOD1 positive sample suggests that metabolic changes occur prior to the onset of clinical symptoms.

2463. In Vivo MR Spectroscopic Changes in the Brain and Spinal Cord After Experimental Spinal Cord Injury in Rats

Johanna Oberg1, Matthias Erschbamer2, Rouslan Sitnikov1, Eric Westman3, Christian Spenger1, Lars Olson2

1CLINTEC, Karolinska Institutet, STOCKHOLM, Sweden; 2Neuroscience, Karolinska Institutet, Sweden; 3NEUROTEC, Karolinska Institutet, Sweden

A variety of tests of sensorimotor function are used to characterize outcome after experimental spinal cord injury (SCI). These tests, however, do not provide information about chemical and metabolic processes in the injured CNS. Here, proton magnetic resonance spectroscopy (MRS) was used to monitor chemical changes in CNS (brain and spinal cord) in vivo following SCI. Significant differences were found between control rats and injured rats. Multivariate data analysis was applied. Our findings suggest that MRS is a helpful tool to monitor metabolic changes in vivo in the brain and the spinal cord itself after spinal cord injury.

2464. High-Field in Vivo 1H-MR Spectroscopy of the Injured Mouse Spinal Cord. Feasibility and Potentiality.

Virginie Callot1, Guillaume Duhamel1, Mohamed Tachrount1, Yann Le Fur1, Patrick J. Cozzone1

1Centre de Résonance Magnétique Biologique et Médicale (CRMBM), CNRS, UMR 6612, Faculté de Médecine, Marseille, France

Non invasive investigations of the mouse spinal cord pathologies are currently based on anatomic and diffusion MRI. In this work, we investigated whether high-field MR Spectroscopy would be able to provide complementing biochemical information useful to describe the lesion and the repair processes. This preliminary study demonstrates the feasibility of longitudinal follow-ups with localized 1H-MRS in injured mouse spinal cord.

2465. In Vivo MR High Resolution T1rho Mapping of the Spine at 3T Using a Reduced-FOV Approach

Ajit Shankaranarayanan1, Emine U. Saritas2, Dwight G. Nishimura3, Weitian Chen1, Eric Han1

1Global Applied Science Lab, GE Healthcare, Menlo Park, CA, United States; 2Dept of Electrical Engineering, Stanford University, Palo Alto, CA, United States; 3Dept of Electrical Engineering, Stanford University, Palo Alto, CA, United States

It has been suggested that MR T1ñ relaxation time may potentially be valuable to assess proteoglycan (PG) loss in the early stages of disc degeneration, a known cause for back pain. Previous T1ñ mapping techniques have shown this to be true. However, clinical applicability of these techniques in spine is somewhat limited by either long scan time, lower resolution or insufficient coverage. This work aims to overcome these limitations by applying reduced-FOV technique, previously shown for diffusion imaging to T1ñ imaging. In vivo experiments have been performed on 3T to show the usefulness of such a targeted approach in terms of higher resolution and shorter scan times while providing good coverage in spine.

2466. Ultrashort TE Imaging After Percutaneous Vertebroplasty

Akio Hiwatashi1, Takashi Yoshiura1, Koji Yamashita1, Hironori Kamano1, Hiroshi Honda1

1Clinical Radiology, Kyushu University, Fukuoka, Japan

uTE is feasible to evaluate cement distribution after percutaneous vertebroplasty

2467. Bone Marrow Perfusion Magnetic Resonance Imaging in Patients with Osteoporotic Vertebral Compression Fractures: Peak Enhancement Ratio Is an Independent Predictor for Intraosseous Vacuum Phenomena

Wei-Che Lin1,2, Hsiu-Ling Chen1, Yu-Fan Cheng1, Chun-Chung Lui1

1Department of Diagnostic Radiology, Chang Gung Memorial Hospital - Kaohsiung Medical Center, Chang Gung University College of Medicine, Kaohsiung, Taiwan, Taiwan; 2Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan, Taiwan

Decrease bone marrow perfusion as reflected by lower peak enhancement ratio (PER) value in dynamic contrast-enhanced MRI (DCE-MRI) can independently predict the presence of intraosseous cleft in patients with osteoporotic vertebral compression fractures.DCE-MRI can help distinguish the more frail patients after VCF suitable for more tailored anti-osteoporotic therapy and can also identify delicate osteoporotic patients for advance treatment before an injury can occur.

2468. Quantitative Assessment of the Cervical Spinal Cord Damage in Neuromyelitis Optica Using Diffusion Tensor Imaging at 3T

Wenshu Qian1, Henry Mak1, Queenie Chan2, Koon Ho Chan3, Mina Kim1

1Diagnostic Radiology, The University of Hong Kong, Hong Kong, China; 2Philips Healthcare, Hong Kong, China; 3Medicine, The University of Hong Kong, Hong Kong, China

Neuromyelitis optica (NMO) is an inflammatory and demyelinating disease which consists of optic neuritis and myelitis. Since it usually involves acute and severe attacks, early diagnosis is of vital importance for proper treatment. However, current diagnostic imaging techniques are not sensitive to degenerative changes in early stage of NMO. In this study, we aimed to investigate the normal appearing cervical spinal cord damage in patients with NMO using diffusion tensor imaging (DTI). Our results show DTI-derived metrics can sensitively assess the microstructural abnormalities, suggesting DTI may have great potential as a useful diagnostic tool in detecting early stage of NMO.

Breast MR

Hall B Tuesday 13:30-15:30

2469. High Resolution MR Imaging and Spectroscopy of the Human Breast at 7T Using a Focused Field RF Coil Setup

Dennis WJ Klomp1, Alexander Raaijmakers2, Mies Korteweg1, Bart van de Bank1, Cecilia Possanzini3, Vincent Boer1, Fredy Visser3, Nico van de Berg2, Peter Luijten1

1Radiology, University Medical Center Utrecht, Utrecht, Netherlands; 2Radiotherapy, University Medical Center Utrecht, Utrecht, Netherlands; 3Philips Health Care

MRI of the human breast at higher B0 fields, like 7T, can improve SNR, but may be restricted by non uniform excitation and restricted RF power deposition (SAR). Here we propose the use of a RF coil setup with focused field in the female breast to gain from the maximum sensitivity that can be obtained at 7T, illustrated by high resolution MRI and MRS in healthy subjects and patients.

2470. Simple Approach for Increasing SNR, Reducing Breast Shading and Improving Fat Suppression at 3T

Ileana Hancu1, Laura Sacolick2, Seung-Kyun Lee1, W Thomas Dixon1, Randy Giaquinto1, Graeme McKinnon3, Vijayanand Alagappan4

1GE Global Research Center, Niskayuna, NY, United States; 2GE Global Research Center, Munich, Germany; 3GE Healthcare, Waukesha, WI, United States; 4GE Healthcare, Aurora, OH, United States

The main cause of the shading and improper fat suppression artifacts in breast imaging at 3T was identified as a bimodal distribution of the excitation field. A correction approach, based on the permanent placement of a passive loop tuned to 150MHz over the (always weaker) right side of a standard 8 channel breast receive array, was shown to mitigate the problem, result in more uniform B1transmit, better fat suppression and higher SNR, all with lower specific absorption rate.

2471. Differentiation Between Intermingled and Central Type Breast Parenchymal Patterns Using Quantitative Morphological Parameters Based on Segmented Dense Tissue

Ke Nie1, Jeon-Hor Chen1,2, Daniel Chang1, Chieh-Chih Hsu2, Orhan Nalcioglu1, Min-Ying Lydia Su1

1Tu & Yuen Center for Functional Onco-Imaging, University of California, Irvine, Irvine, CA, United States; 2Department of Radiology, China Medical University, Taichung, Taiwan

Breast parenchymal pattern is a well-known risk factor. The commonly used term ¡®breast density¡¯ only measures the amount of breast tissue, not the relative distribution between the fat and fibroglandular tissue. In this study, we developed quantitative parameters to characterize different parenchymal distribution patterns (intermingled vs. central types) based on the segmented dense tissue on 3D MRI. In a dataset of 230 cases, the area under the ROC curve could reach to 0.94 using combined parameters. These features can be further used to investigate the relationship between parenchymal pattern and the cancer risk.

2472. Evaluation of Neoadjuvant Chemotherapy Response of Breast Cancer at 3.0T

Jeon-Hor Chen1,2, s Bahri1, P Carpenter3, H-J Yu1, R Mehta4, O Nalcioglu1, M-Y Lydia Su1

1Center for Functional Onco-Imaging, UC Irvine, Irvine, CA, United States; 2China Medical University Hospital, Taichung, Taiwan; 3Department of Pathology, UC Irvine, Irvine, CA, United States; 4Department of Medicine, UC Irvine, Irvine, CA, United States

The results analyzed from 3.0 T were consistent with our previous findings using 1.5T with a lower spatial resolution, suggesting that the limitation of MRI in diagnosis of post-NAC cancer cannot be improved with a higher SNR or a higher spatial resolution. Our current protocol at 3.0 T still could not detect residual tumor presenting as scattered cells or small foci, which often occurs in non-mass-like lesions. These types of invasive cancer cells do not need angiogenesis to survive, and if so, they will not show contrast enhancements.

2473. Reduction of Breast Density Following Tamoxifen Treatment Evaluated by 3-D MRI

Jeon-Hor Chen1,2, Yeun-Chung Chang3, Daniel Chang1, Yi-Ting Wang3, Ke Nie1, Ruey-Feng Chang3, orhang Nalcioglu1, Chiun-Sheng Huang3, M-Y Lydia Su1

1Center for Functional Onco-Imaging, UC Irvine, Irvine, CA, United States; 2China Medical University Hospital, Taiwan; 3National Taiwan University, Taiwan

We have demonstrated that the breast density analyzed based on a 3D MR method can be used to investigate the changes associated with tamoxifen treatment. We found a significant reduction in fibroglandular tissue volume and percent breast density after treatment, and the density reduction was positively correlated with the baseline density and treatment duration.

2474. MRI Evaluation of Decrease of Breast Density in the Contralateral Normal Breast of Patients Receiving Neoadjuvant Chemotherapy

Jeon-Hor Chen1,2, Ke Nie1, S Bahri1, Rita S. Mehta3, Chieh-Chih Hsu2, Fei-Ting Hsu2, Han-Ni Shih2, Muqing Lin1, orhang Nalcioglu1, M-Y Lydia Su1

1Center for Functional Onco-Imaging, UC Irvine, Irvine, CA, United States; 2China Medical University Hospital, Taichung, Taiwan; 3Department of Medicine, UC Irvine, Irvine, CA, United States

We have demonstrated the feasibility of investigating the reduction of density following chemotherapy using a quantitative analysis method based on MRI. Patients receiving chemotherapy showed reduction of breast density, and that the effects were more pronounced in younger women than older (post-menopausal) women. The results suggest that the reduction of breast density after chemotherapy was possibly mediated through impaired ovarian function. The reduction could be clearly noted after 1 to 2 cycles of AC regimen. Although the density continued to decrease after 4 cycles of AC and the following Taxane regimen, the subsequent effect was smaller.

2475. Pushing Old Boundaries in Breast MRI: Non-Fatsaturated Dynamic Imaging at Very Short TE

Christian Geppert1, Rolf Janka2, Berthold Kiefer1, Michael Uder2, Evelyn Wenkel2

1MR Oncology, Siemens Heatlthcare, Erlangen, Germany; 2Radiologisches Institut, Universitätsklinikum Erlangen, Erlangen, Germany

In non-fatsuppressed dynamic breast imaging, it is a well accepted recommendation to acquire data at or close to echo times that fulfil the in-phase condition for fat and water, such as 4.7ms at 1.5T, in order to avoid partial volume effects that lead to signal cancellation at fat/water interfaces. Thus it is usually suggested of using either in-phase TE or “TE less than 1.2ms” resulting in a phase difference of below 90°. In a comparable parameter setting this would result in a decrease of 50% of the total acquisition time. With current gradient systems and fast imaging sequences this has now become possible without compromising the matrix size or the bandwidth. In this work we have set up an interleaved protocol approach to achieve a direct comparison of a minimum TE acquisition with a clinical standard protocol.

2476. Improved Diagnostic Accuracy in DCE MR-Mammography by Normalization of Kinetic Parameters Following AIF Deconvolution

Endre Grøvik1, Kjell-Inge Gjesdal2, Kathinka Kurz Dæhli3, Atle Bjørnerud4

1University of Oslo, Oslo, Norway; 2Sunnmøre MR-klinikk, Aalesund, Norway; 3Stavanger University Hospital, Stavanger, Norway; 4Rikshospitalet University Hospital, Oslo, Norway

This work presents a method for improving diagnostic accuracy in DCE MR-mammography by normalization of kinetic parameters following AIF deconvolution. The permeability related kinetic parameter Ktrans and the Ktrans-ratio between cancer tissue and breast parenchyma were investigated and compared based on their ability to differentiate between malignant and benign lesions. The result showed that employing a normalization approach may improve the diagnostically performance of the pharmacokinetic model by diminishing the prospective errors in the extracted AIF.

2477. Influence of Contrast Arrival Time and Temporal Resolution in Diagnosis of Breast Cancer with DCE-MRI

Hendrik Laue1, Anja Hennemuth1, Volker Diehl1,2, Markus Thorsten Harz1, Horst Karl Hahn1, Heinz-Otto Peitgen1

1Fraunhofer MEVIS, Bremen, Germany; 2Institute of Magnetic Resonance Imaging, Central Hospital St.-Juergen-Strasse, Bremen, Germany

The consensus on diagnosis of breast cancer with DCE-MRI is the use of sequences with high spatial and low temporal resolution, because of the in inhomogeneous distribution of pharmacokinetic properties in the tumor and the requirement to detect small lesions. The diagnostic in breast MRI today is therefore based on simple curve shapes rather than pharmacokinetic modeling. In this work, some pharmacokinetic modeling of contrast arrival time (CAT) and variation of low temporal resolution are carried out to identify pitfalls in the application and to identify techniques beneficial for the diagnostic performance of breast MRI.

2478. Preliminary Results Using a Split Dynamic Time Series for DCE MR-Mammography

Kjell-Inge Gjesdal1, Endre Grøvik2, Atle Bjørnerud3, Kathinka Kurz Dæhli4

1Sunnmøre MR-klinikk, Aalesund, Norway; 2University of Oslo, Oslo, Norway; 3Rikshospitalet University Hospital, Oslo, Norway; 4Stavanger University Hospital, Stavanger, Norway

This work presents the preliminary results of an ongoing MR-mammography study. In this study two dynamic sequences are run in an interleaved fashion during contrast enhancement. By using this approach both high temporal and high spatial resolution images can be produced and analyzed for the evaluation of breast cancer using one single dose of a Gd-based contrast agent. A comprehensive list of biomarkers is presented along with their statistical values.

2479. Can Diffusion Weighted Imaging/Apparent Diffusion Coefficient Mapping and Dynamic Contrast Magnetic Resonance Imaging Provide Histological Phenotyping of Breast Cancer in Basal and Luminal Subtypes?

Michael A. Jacobs1, Riham H. El Khouli2, Katarzyna J. Macura1, Sarah Mezban1, Ihab Kamel1, David A. Bluemke2

1The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, United States; 2Department of Radiology and Imaging Sciences, National Institutes of Health, Bethesda, MD, United States

By using a combined DWI/ADC and DCE approach to investigate histological characteristics of breast cancer a better understanding of breast cancer aggressiveness can be realized. Functional imaging such as DWI and DCE-MR is feasible and thus, combined DWI/ADC mapping, and DCE-MR provides radiological biomarkers of molecular environment and could provide targets for image-guided biopsy of highly aggressive tumor regions.

2480. Principal Component Analysis of Breast DCE-MRI: Evaluation of Clinical Protocols at Two Temporal Resolutions

Daria Badikhi1, Myra Shapiro-Feinberg2, Erez Eyal3, Edna Furman-Haran4, Dov Grobgeld1, Hadassa Degani1

1Biological Regulation, Weizmann Institute of Science, Rehovot, Israel; 2Radiology, Meir Medical Center, Kfar Sabah, Israel; 3Biological Regulation, Weizmann Institute of Science, Israel; 4Biological Services, Weizmann Institute of Science, Rehovot

Principal component analysis (PCA) of clinical breast DCE MRI datasets, recorded at two different temporal resolutions (80 s and 120 s), was tested and evaluated for its diagnostic ability. We found that PCA can differentiate with high accuracy between benign and malignant lesions at both temporal resolutions, however, discriminative ability between invasive ductal and lobular carcinoma can be reached only at the higher temporal resolution. Overall, PCA was found to be a useful, standardized, fast, and objective tool for computer aided diagnosis of breast lesions

2481. Diffusion Weighted and Dynamic Contrast Enhanced MRI in Evaluation of Treatment Effects During Neoadjuvant Chemotherapy in Breast Cancer Patients

Line R. Jensen1, Benjamin Garzon1, Mariann G. Heldahl1, Tone F. Bathen1, Pål E. Goa1, Steinar Lundgren1,2, Ingrid S. Gribbestad1

1Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway; 2Department of Oncology, St. Olavs University Hospital, Trondheim, Norway

The purpose of this study was to use MRI for early evaluation of treatment effects in breast cancer patients undergoing neoadjuvant chemotherapy, and to identify MRI parameters at 3T that correlate to treatment response. In addition, the reproducibility of diffusion weighted MRI was assessed. The ADC values from two baseline examinations showed good reproducibility, with ICC of 0.84. The best predictors of pathologic treatment response were the change in the longest diameter measured on MRI, followed by mean and skewness of ADC, and Ktrans entropy.

2482. Assessing 3D Resolution of DCE-MRI for Optimization and Standardization of Breast Screening Protocols

Marco Borri1, Maria Schmidt1, Erica Scurr1, Toni Wallace1, Steven Allen1, Nandita deSouza1, Martin O. Leach1

1CR-UK and EPSRC Cancer Imaging Centre, Institute of Cancer Research and Royal Marsden Hospital, Sutton, Surrey, United Kingdom

Spatial resolution of 3D fat-suppressed DCE pulse sequences depends on many parameters, and parity of protocols across breast screening centres is highly desirable. The objective of this work was to propose methods for quality assurance in breast screening programmes. We compared the image quality achieved with two different k-space sampling patterns, Radial and Linear, on a breast screening sequence. Resolution was evaluated with Test Objects and on Clinical Data, and, considering all three directions, was superior for Linear. The Image Analysis methodologies used were found to be robust and reproducible, and are therefore candidates to become quality assurance tools.

2483. Influence of Spatial Heterogeneity on the Diagnostic Accuracy of DCE-MRI in Breast Tumor Characterization

Endre Grøvik1, Kjell-Inge Gjesdal2, Kathinka Kurz Dæhli3, Atle Bjørnerud4

1University of Oslo, Oslo, Norway; 2Sunnmøre MR-klinikk, Aalesund, Norway; 3Stavanger University Hospital, Stavanger, Norway; 4Rikshospitalet University Hospital, Oslo, Norway

This study investigates the influence of spatial heterogeneity on the diagnostic accuracy of DCE-MRI in breast tumor characterization. This is done by comparing the lesions VOI 50th-percentile versus VOI 95th-percentile values for a defined set of pharmacokinetic parameters, based on their ability for differentiating between malignant and benign lesions. Our results suggest that a significant improvement in diagnostic accuracy can be obtained by identifying the 5% region indicating the highest malignancy in the defined tumor VOI.

2484. Preliminary Results of a Physical Phantom for Quantitative Assessment of Breast MRI

Melanie Freed1,2, Jacco A. de Zwart3, Jennifer T. Loud4, Riham H. El Khouli5, Mark H. Greene4, Brandon D. Gallas1, Kyle J. Myers1, Jeff H. Duyn3, David A. Bluemke5, Aldo Badano1

1CDRH/OSEL/DIAM, FDA, Silver Spring, MD, United States; 2Department of Bioengineering, University of Maryland, College Park, MD, United States; 3NINDS/LFMI/Advanced MRI Section, National Institutes of Health, Bethesda, MD, United States; 4NCI/Clinical Genetics Branch, National Institutes of Health, Rockville, MD, United States; 5Department of Radiology and Imaging Sciences, National Institutes of Health, Bethesda, MD, United States

We are developing a physical, tissue-mimicking phantom to be used for task-based, quantitative assessment of breast MRI protocols. Here we present initial results of the phantom characterization and comparison to human data. Measured T1 and T2 relaxation values of the adipose- and glandular-mimicking phantom components agree with human values from the literature. The structure of human and phantom images is compared using the covariance kernel and found to match within patient variation.

2485. DSC MR-Mammography: Tumor Characterization Using Quantitative R2* Analysis

Endre Grøvik1, Kathinka Kurz Dæhli2, Atle Bjørnerud3, Kjell-Inge Gjesdal4

1University of Oslo, Oslo, Norway; 2Stavanger University Hospital, Stavanger, Norway; 3Rikshospitalet University Hospital, Oslo, Norway; 4Sunnmøre MR-klinikk, Aalesund, Norway

This work presents the transverse relaxation rate, R2*, as a quantitative biomarker for distinguishing between malignant and benign breast lesions. R2* was estimated on a pixel-by-pixel basis by assuming a mono-exponential dependence of a double-echo intensity scheme, yielding from a high temporal resolution sequence. The study suggested that the peak change in the transverse relaxation rate is a sensitive biomarker for tumor malignancy in DSC MR-mammography.

2486. Simulation of Breast Tumor Growth from In-Situ to Invasive Cancer Using a Mathematical Model to Correlate with Lesion Phenotypes Shown on MRI

Ke Nie1, Jeon-Hor Chen1,2, Orhan Nalcioglu1, Min-Ying Lydia Su1

1Tu & Yuen Center for Functional Onco-Imaging, University of California, Irvine, Irvine, CA, United States; 2Department of Radiology, China Medical University, Taichung, Taiwan

Mathematical modeling provides a unique means to simulate different cancer growth patterns. However, the current published models included only functional information, few of them considered the effect of environmental structure. In this study, we simulated the breast tumor growth in the duct by coupling tumor growth and duct wall deformation. By varying the key parameters, we could identify key mechanisms for DCIS to progress to invasive cancer. The simulation result is further correlated with the lesion phenotype shown on MRI. Understanding these biological growth patterns of DCIS may be further used to refine diagnostic criteria.

2487. MRI Detection of Small Calcium Crystals in Air Bubble-Free Agarose Phantoms: Potential Applications to Imaging Microcalcifications in Breast Cancer

Bo Elizabeth Peng1, Sean Foxley2, Jeremy Palgen1, Robin Holmes2, Elizabeth Hipp2, Gillian Newstead2, Gregory S. Karczmar2, Devkumar Mustafi1,2

1Biochemistry & Molecular Biology, The University of Chicago, Chicago, IL, United States; 2Radiology, The University of Chicago, Chicago, IL, United States

We tested several MRI methods for the identification and characterization of small calcium crystals for probing microcalcifications in breast cancer. High-resolution MR images were acquired of small Ca-crystals imbedded in air bubble-free agarose phantoms in clinical and research magnets. Two types of Ca-crystals that are commonly associated with benign and malignant breast lesions, are clearly detectable and distinguishable by MRI, but not distinguishable on x-ray mammograms. The present results lend support to the feasibility of clinical visualization and analysis of microcalcifications by MRI. Detection of microcalcifications by MRI would increase sensitivity and specificity for breast cancer detection.

2488. Microcalcification Detection Using Susceptibility Weighted Phase Imaging: Cross-Correlation and Relative Magnetic Susceptibility Difference Methods

Richard Baheza1, Brian Welch2, John Gore3, Thomas Yankeelov3

1Biomedical Engineering, Vanderbilt, Nashville, TN, United States; 2Philips Healthcare; 3Institute of Imag Science and Dep of Radiology Sciences, Vanderbilt, Nashville, TN, United States

The possibility of detecting calcium deposits in breast has been investigated by simulation and experimentally. Susceptibility weighted imaging is used to simulate and measure signature due to magnetic susceptibility difference between calcium and water in tissue. Simulated and experimental data with different levels of signal to noise ratio (SNR) and resolution are analyzed by two methods. Crosscorrelation between simulated phase and data, and the relative magnetic susceptibility difference map, computed directly from data. Both methods are compared to locate 1mm object induced signature. Results suggest SNRâ‰¥20 and voxel size â‰¤ 0.25 mm (isotropic) are needed for both methods to work.

2489. Detection of Breast Micro-Calcifications with MRI at 3T:

Riham Hossam El Din El Khouli1, David Thomasson1, Katarzyna Macura2, Sarah Mezban2, wei Liu3, Michael Jacobs2, Richard Edden4, Peter Barker2, David Bluemke1

1Radiology and Imaging Sciences, NIH/Clinical Center, Bethesda, MD, United States; 2Radiology and Radiological Sciences, Johns Hopkins University School of Medicine; 3NIH/NCI; 4Cardiff University

Micro-calcifications (< 1 mm) are a fundamental marker of breast cancer by x-ray mammography, especially for the early diagnosis of ductal carcinoma in situ (DCIS). However with MRI, micro-calcifications are rarely detected using standard pulse sequences. The purpose of this study was to optimize MRI approaches for detecting micro-calcifications in the breast in comparison to mammography and conventional MRI. We achieved high spatial resolution and good visualization of micro-calcifications using a proton density weighted ultra-short TE MRI sequence with radial reconstruction. Ultra-short TE MRI has potential for detection of mammographically visualized micro-calcifications.

2490. Distinguishing Molecular Subtypes of Breast Cancer Based on Computer-Aided Diagnosis of DCE-MRI

Shannon Agner1, Mark Rosen2, Sarah Englander2, Diana Sobers1, Kathleen Thomas2, John Tomaszewski3, Michael Feldman3, Shridar Ganesan1, Mitchell Schnall2, Anant Madabhushi1

1Biomedical Engineering, Rutgers University, Piscataway, NJ, United States; 2Radiology, University of Pennsylvania, Philadelphia, PA, United States; 3Pathology, University of Pennsylvania, Philadelphia, PA, United States

Previous studies based on visual inspection of breast tumors suggest that molecular subtypes of breast cancer are associated with distinct imaging phenotypes on DCE-MRI. In this study, we develop a computer-aided diagnosis tool that utilizes textural kinetics, an attribute that captures time related changes in internal lesion texture, to distinguish between 20 triple negative (estrogen receptor (ER) negative/ progesterone receptor (PR) negative/ human epidermal growth factor (HER2) receptor negative) and 21 ER positive tumors. Our CAD system was found to outperform classifiers that were driven by morphology, signal intensity kinetics, peak contrast texture, and pharmacokinetic parameters.

2491. Improved 3D MR Imaging Using Virtual Coil Deconvolution for Effective Density Weighted Imaging (VIDED)

Marcel Gutberlet1, Anne Roth1, Dietbert Hahn1, Herbert Köstler1

1Institut fuer Roentgendiagnostik, University of Wuerzburg, Wuerzburg, Bavaria, Germany

A novel method is presented allowing improving 3D-MRI. Virtual coil deconvolution imaging for effective density weighted imaging (VIDED) combines the virtual coil concept with density weighted imaging. DW imaging allows improving the spatial response function at an optimal signal-to-noise ratio but at the expense of incoherent aliasing. In VIDED imaging this aliasing is suppressed by virtual coil deconvolution imaging which is a method allowing parallel imaging even for single receiver coils. VIDED imaging was applied in slice direction of 3D-MRI improving the slice profile, increasing the SNR up to 17% and the FOV in slice direction approximately by 25%.

2492. Saturation-Recovery Snapshot FLASH Reduces RF Pulse Angle Inhomogeneity Artefacts in DCE-MRI of the Breast at 3T.

Che A. Azlan1,2, Trevor S. Ahearn1, Pierluigi Di Giovanni1, Scott I.K. Semple3, Fiona J. Gilbert1, Thomas W. Redpath1

1Aberdeen Biomedical Imaging Centre, University of Aberdeen, Aberdeen, Scotland, United Kingdom; 2Department of Biomedical Imaging, University of Malaya, Kuala Lumpur, Malaysia; 3Department of Medical Physics, University of Edinburgh, Edinburgh, Scotland, United Kingdom

The objective of this study was to evaluate the effectiveness of Hoffmann's method of saturation-recovery snapshot FLASH (SRSF) to minimise the effect of radiofrequency (RF) pulse angle inhomogeneity in breast dynamic contrast-enhanced (DCE)-MRI at 3T. We employed computer simulation and experiment on gel phantom for this purpose. The simulation shows that Hoffmann’s SRSF produces a robust saturation in the presence of expected RF inhomogeneity. The enhancement ratio data acquired broadly matches the simulation. Implementing this method may be a solution to minimise the effects of RF pulse angle inhomogeneity in DCE-MRI of the breast at 3T.

2493. Patient-Specific Calibration for Breast MRI: Breast-Coil Insertable Reference Phantom

Marieke Heisen1, Bo Peng2, Abbie Marie Wood3, Devkumar Mustafi2,3, Johannes Buurman4, Gillian M. Newstead3, Gregory S. Karczmar3

1Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands; 2Biochemistry & Molecular Biology, The University of Chicago, Chicago, IL, United States; 3Radiology, The University of Chicago, Chicago, IL, United States; 4Healthcare Informatics, Philips Healthcare, Best, Netherlands

A unique calibration phantom was designed for routine use in breast MRI. It was used to correct the variable flip angles in a precontrast T1-measurement, and to inspect T1 sensitivity in the clinically employed T1-weighted dynamic contrast-enhanced protocol. The flip angle correction altered the T1 estimates in breast tissue significantly. The clinical protocol demonstrated an increase in signal intensity for decreasing T1 (as expected) until a certain level, after which signal attenuation occurred. The quality of the breast images acquired with the phantom in place was found to be normal by an experienced mammographer.

2494. MR Imaging Features of Invasive Lobular Carcinoma: A Comparison with Invasive Ductal Carcinoma

Sung Hun Kim1, Jae Young Byun1, Eun Suk Cha1, Hyun Sook Kim1, Jae Jeong Choi1

1Radiology, College of Medicine, the Catholic University of Korea, Seocho gu, Seoul, Korea, Republic of

Invasive lobular carcinoma (ILC) is the second most common breast cancer after invasive ductal carcinoma (IDC). The incidence of ILC has continuously increased probably due to hormone replacement therapy. There were little studies to compare the imaging findings of ILC and IDC according to BI-RADS. The purposes of our study were to characterize the mammographic and MR imaing features of ILC and to compare these imaging features with those of IDC. Furthermore, the multiplicity and MRI diagnostic accuracy to detect the multiplicity apart from the index mass were determined.

2495. BOLD Imaging of Compressed Breast Hemodynamics

Stefan Alexandru Carp1, Azma Mareyam1, Lawrence Wald1, David Alan Boas1

1Radiology, Massachusetts General Hospital, Charlestown, MA, United States

External compression induced hemodynamic changes in the breast have recently been investigated as potential biomarkers of breast cancer. Using fast diffuse NIR spectroscopy our group has demonstrated the non-invasive estimation of breast tissue blood flow and oxygen consumption. Consequently, we have designed an integrated MRI-optical breast compression platform for simultaneous acquisition of MR and optical images. MR scans provide structural prior information for optical reconstructions, as well as hemodynamic (BOLD) images for cross-validation against optically measured deoxy-hemoglobin. We describe the MRI breast compression platform and present initial results demonstrating contrast between the BOLD signal evolution in fibro-glandular vs. adipose tissue.

2496. Development of Tissue Susceptibility Matched Pyrolytic Graphite Foam for Improved Frequency Selective Fat Suppression and Motion Suppression in Breast MRI

Gary Lee1, Patrick Goodwill1, Kevin Phuong2, Ben Inglis3, Brian Hargreaves4, Steven Conolly1,2

1Berkeley/UCSF Bioengineering Joint Graduate Group, Berkeley, CA, United States; 2Bioengineering, University of California - Berkeley, Berkeley, CA, United States; 3Henry J Wheeler, Jr. Brain Imaging Center, Berkeley, CA, United States; 4Radiology, Stanford University, Palo Alto, CA, United States

DCE breast MRI is emerging as the second most common diagnostic imaging modality for breast cancer, which has ~200,000 new cases and ~40,000 deaths annually. However, breast MRI still lacks adequate specificity. Magnetic susceptibility mismatches near the breast/air interface contribute to field inhomogeneities which make frequency selective fat suppression techniques more difficult. We have developed tissue susceptibility matched pyrolytic graphite foam that is lightweight, safe for patients, and compatible with embedded RF coils. PG foams may improve frequency selective fat suppression for breast MRI and provide more robust motion suppression, which may lead to improved specificity in breast cancer diagnosis.

2497. Cactus Spines as Fiducials for MRI and Pathology Correlation of Ex-Vivo Human Lymph Nodes

Mies A. Korteweg1, Jaco J.M. Zwanenburg1, Cristian Koolstra, Paul J. van Diest2, Arjen J. Witkamp3, Willem P.Th.M. Mali1, Peter R. Luijten1, Wouter B. Veldhuis1

1Radiology, University Medical Center Utrecht, Utrecht, Netherlands; 2Pathology, University Medical Center Utrecht, Utrecht, Netherlands; 3Surgery, University Medical Center Utrecht, Netherlands

We describe the properties and suitability of cactus spines used as fiducial markers in ex-vivo human lymph nodes for the correlation of MRI to histopathology. In 42 nodes cactus spines were inserted before scanning at 7T. Afterwards the nodes were pathologically examined. Geometric distortions, susceptibility- or pathologic examination artifacts and identification on MRI were scored. Cactus spines were readily identified both on MRI and at histopathology. No interference was noted for either analysis. It was concluded that cactus spines are suitable fiducials which aid in the accurate correlation of intranodal imaging features to histopathology.

2498. Local Excitation Important for Breast MR: Signal Energy from Outside the FOV Decreases Contrast Using Non-Cartesian Acquisitions

Matt Smith1, Krishna Kurpad2, Catherine Moran1, Xu Zhai1, Walter Block1,3, Sean Fain1,3

1Medical Physics, University of Wisconsin, Madison, WI, United States; 2Radiology, University of Wisconsin, Madison, WI, United States; 3Biomedical Engineering, University of Wisconsin, Madison, WI, United States

Regardless of the sampling technique, the volume of interest is degraded by excited signal energy outside the FOV. With 3D non-Cartesian acquisitions, the effect is incoherent streaking with noise-like appearance. Commercial receive only breast coils require slice/slab excitation from the body coil, exciting tissue outside the FOV. A local transmit/receive breast coil based on a solenoid design is compared with a commercial receive-only coil to demonstrate that local excitation minimizes the unwanted signal energy contaminating the FOV for non-Cartesian breast MR. Measurements of contrast are higher and more consistent using a 3DPR SSFP sequence with a local transmit/receive breast coil.

2499. Adaptive 3D Radial MRI Based on Multidimensional Golden Means for Supine Breast Imaging

Peter Siegler1, Rachel W.-C. Chan2, Elizabeth A. Ramsay1, Donald B. Plewes1

1Imaging Research, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada; 2Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada

Dynamic contrast-enhanced breast MRI shows a high sensitivity for breast cancer but is commonly done in prone position which complicates its use for image-aided strategies. Recently, supine unilateral breast MRI with compensation for respiratory motion was successfully implemented. However, standard Cartesian sampling has no isotropic spatial resolution, which is desirable for image-aided applications. Here, 3D projection reconstruction based on multidimensional golden means was tested for use in supine breast MRI. The technique allowed post-processed compensation for respiratory motion, which is intrinsic in a supine position of the patient, without the need to choose any motion-compensation settings prior to the scan.

2500. Towards a Microspectroscopy Catheter for Early-Stage Breast Cancer Detection

Debra Strick Rivera1, Jack W. Judy2, W Gilbert Clarke2, Dixie J. Mills3, Allen C. Chu2, Mark S. Cohen2

1Neurophysics, Max Planck Institute, Leipzig, Saxony, Germany; 2University of California, Los Angeles; 3Dr. Susan Love Research Foundation

Early-detection of breast cancer is unreliable, and of increased importance due to encouraging results of intraductal application of chemotherapy. We present a prototype radio-frequency transceiver for intraductal microspectroscopy, including soak-tests and heating studies. We demonstrate that the microcoil prototype is capable of resolving fat and water spectra in a sample with 5000-fold fewer spins than a state of the art matrix coil.

2501. Breast Perfusion Imaging Using Arterial Spin Labeling

Misung Han1,2, Brian A. Hargreaves1, Bruce L. Daniel1, David C. Alsop3,4, Philip M. Robson, 4,5, Eric Han6, Pauline W. Worters1, Ajit Shankaranarayanan6

1Radiology, Stanford University, Stanford, CA, United States; 2Electrial Engineering, Stanford University, Stanford, CA, United States; 3Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States; 4Radiology, Harvard Medical School, Boston, MA, United States; 5Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School , Boston, MA, United States; 6Applied Science Lab, GE Healthcare, Menlo Park, CA, United States

Malignant breast tumors induce high level angiogenesis, resulting in increased vascularity and perfusion. For breast MRI, dynamic contrast-enhanced MRI is most widely used to detect and characterize tumors; on the other hand, arterial spin labeling (ASL) technique is very challenging due to low baseline flow in breasts. Here, we show our experience in 2D breast ASL using FAIR labeling and background suppression in both volunteers and patients. With our technique, higher perfusion signal was depicted in tumor.

2502. Improved Fat Suppression with High Resolution Balanced Steady State Imaging in the Breast

Dorothee Barbara Engel1, Catherine Judith Moran2, Fred Kelcz3, Stephan O. Schoenberg1, Walter Block2

1Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim, Mannheim, Germany; 2Department of Medical Physics, University of Wisconsin, Madison, WI, United States; 3Department of Radiology, University of Wisconsin, Madison, WI, United States

While the Dynamic Contrast Enhanced (DCE) acquisition remains the centerpiece of breast MRI, both signal intensity and the depiction of lesion morphology in T2-weighted images can help to distinguish malignant versus benign lesions. With TRs on the order of seconds, T2-weighted acquisitions are generally inefficient and most often acquired with high in-plane resolution but low through plane resolution. A radial bSSFP acquisition termed 3DPR-SSFP has been shown to provide improved depiction of lesion morphology in comparison to conventional T2-weighed acquisitions. We evaluate the performance of two methods for improving fat suppression of 3DPR-SSFP while retaining the advantage of clear depiction of fine morphological details in the breast.

2503. Resolving Arterial Phase in Dynamic Breast MRI Using a Fast TWIST Acquisition During Injection Delay

Karl-Heinz Herrmann1, Pascal A. Baltzer, Ines Krumbein, Christian Geppert2, Werner A. Kaiser, Jürgen R. Reichenbach1

1Medical Physics Group, Department of Diagnostic and Interventional Radiology, University Hospital Jena, Jena, Thüringen, Germany; 2MR Oncology, Siemens Healthcare, Erlangen

In MR Mammography pathologic vascularisation is utilized for the diagnosis of tumors. Many standard dynamic MRM protocols contain a delay of 35s, during which the contrast agent is applied, between the native scan and the following multiple post-CA scans. This injection delay can be efﬁciently used to acquire additional dynamic data sets with both high temporal (5.7s) and spatial resolution (0.9x0.9x1.5mm) using a 3D gradient echo view sharing sequence with stochastic trajectories (TWIST). This allows to resolve the arterial phase of the contrast agents ﬁrst pass and helps to detect anomalous arterial supply vessels to suspect lesions.

Lung & Mediastinum MRI

Hall B Wednesday 13:30-15:30

2504. Inflammation Assessment in the Lungs of LPS-Challenged Rodents: Comparison Between Radial Ultra-Short Echo Time (UTE) and Cartesian MR Imaging

Magdalena Zurek1, Laura Carrero-Gonzalez2,3, Selina Bucher2, Thomas Kaulisch2, Detlef Stiller2, Yannick Crémillieux1

1Université de Lyon, Laboratoire CREATIS-LRMN, Lyon, France; 2Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach, Germany; 3Universidad Complutense de Madrid, Madrid, Spain

A radial ultra short-echo time (UTE) sequence has been shown to be appropriate in pulmonary imaging due to its robustness against motion and its improved image resolution. In this study, we evaluated the accuracy of edema detection using two protocols based on conventional-Cartesian and UTE radial imaging approaches. Despite degraded image quality in case of Cartesian images due to the motion, similar inflammation extent was found for both approaches. The UTE technique, applied under free-breathing conditions, will certainly prove to be quite useful in routine MR investigations applied on models of lung diseases associated with inflammation or mucous hypersecretion.

2505. Ultrashort Echo Time (UTE) MR Lung Imaging with Respiratory Motion Compensation

Jiangsheng Yu1, Yiqun Xue1, Hamidreza Saligheh Rad1, Hee Kwon Song1

1Laboratory for Structural NMR Imaging, Department of Radiology,, University of Pennsylvania, Philadelphia, PA, United States

Ultra-short echo time (UTE) MRI has been successfully applied to lung imaging, but so far the issue of respiratory motion during imaging the lung parenchyma has not yet been addressed. In this work, a respiratory motion-compensated UTE lung MRI technique is presented. This technique applies the golden-angle view increment strategy in conjunction with respiratory self-gating to reconstruct images at different respiratory phases to reduce respiratory motion artifacts. The in-vivo results demonstrate that lung image quality is significantly enhanced with improved visualization and delineation of lung vasculature, as well as improved SNR, as compared to conventional gradient echo images.

2506. Comparison of Lung T2* Measurements at 1.5T and 3.0T with Ultrashort Echo Time (UTE) Sequence

Jiangsheng Yu1, Yiqun Xue1, Hee Kwon Song1

1University of Pennsylvania, Philadelphia, PA, United States

Accurate assessments of lung T2* may be important as it has the potential to detect structural and functional changes caused by lung diseases such as emphysema, chronic bronchitis and fibrosis. While measurements have been carried out in both animals and humans at 1.5T, studies on human lung at 3T have not yet been reported. In this work, we compare T2* values in normal human lungs at 1.5T and 3.0T using an ultrashort echo time (UTE) pulse sequence. Results show the average lung T2* of 0.72 (±0.17) ms at 3.0T is considerably shorter than 2.2 (±0.43) ms at 1.5T.

2507. Time-Resolved Lung Perfusion- And Ventilation-Weighted MRI by Wavelet Analysis

Grzegorz Bauman1,2, Julien Dinkel3, Michael Puderbach3, Lothar Rudi Schad2

1Medical Physics in Radiology, German Cancer Research Center, Heidelberg, Germany; 2Computer Assisted Clinical Medicine, University of Heidelberg, Mannheim, Germany; 3Department of Radiology, German Cancer Research Center, Heidelberg, Germany

Non-contrast based assessment of the pulmonary function using MRI remains challenging. We propose a novel post-processing method based on the Wavelet analysis to retrieve information about pulmonary perfusion and ventilation. The method utilizes rapid acquisition of time-resolved MR-data using a 2D Steady-State Free Precession sequence implemented on a 1.5 T whole-body MR-scanner. Wavelet transform allows for a robust analysis of non-stationary physiological signals (respiratory/cardiac cycles). The aim of this study was to show feasibility of the proposed approach.

2508. Improved Visualization of Pulmonary Parenchyma Using SSFP Sequence for Dynamic MR-Studies

Grzegorz Bauman1,2, Michael Deimling3, Michael Puderbach4, Lothar Rudi Schad2

1Medical Physics in Radiology, German Cancer Research Center, Heidelberg, Germany; 2Computer Assisted Clinical Medicine, University of Heidelberg, Mannheim, Germany; 3Siemens Healthcare, Erlangen, Germany; 4Department of Radiology, German Cancer Research Center, Heidelberg, Germany

In lung MRI, due to the fast signal dephasing, respiratory motion and cardiac pulsation, very fast imaging sequences using short repetition times or the application of triggering techniques are required. The aim of this work was to numerically simulate and optimize the Steady-State Free Precession (SSFP) imaging scheme for dynamic studies on a 1.5 T whole-body MR-scanner. Fast imaging with the SSFP sequence using a combination of the central k-space sampling, parallel imaging, high bandwidth and minimal inter-echo sampling allowed to improve the visualization of the pulmonary tissue sufficiently for functional lung MRI.

2509. High Resolution T2 Weighted Lung Imaging with a Radial Turbo Spin-Echo Sequence

Michael Völker1, Philipp Ehses1, Martin Blaimer2, Felix Breuer2, Peter Michael Jakob1,2

1Department of Experimental Physics 5, University of Würzburg, Würzburg, Bavaria, Germany; 2Research Center for Magnetic Resonance Bavaria (MRB), Würzburg, Germany

A segmented radial Turbo Spin-Echo (rTSE) sequence was investigated towards its feasibility for high resolution lung imaging under free breathing conditions. No triggering techniques were involved to define the limits of the sequence itself. Unlike ultrafast singleshot techniques such as HASTE resolution is not intrinsically limited by the T2 signal decay while motion, especially of the beating heart, poses only a small problem in comparison with conventional Cartesian TSE. In addition, arbitrary T2 contrasts may be generated by postprocessing a single dataset allowing for the calculation of quantitative T2 maps.

2510. Proton MRI of Human Lung Using 2D Radial Acquisition at 1.5 T and 3.0 T

Jascha Zapp1, Simon Konstandin1, Lothar R. Schad1

1Computer Assisted Clinical Medicine, Heidelberg University, Mannheim, Germany

MRI of the lung is challenging because of low proton density, respiratory and cardiac motion and susceptibility effects at air-tissue interfaces. A healthy volunteer was examined using a 2D radial gradient echo technique (resolution: 0.8mm x 0.8mm x 5.0mm) with conventional (full) RF pulses (TE=0.77ms) and half RF pulses (TE=0.02ms) at 1.5T and 3.0T. Average SNR in lung parenchyma resulted in an increase of 56% at 3.0T compared to 1.5T with TE=0.02ms. The result shows that SNR in proton MRI of human lung at 3.0T is superior to 1.5T when using a 2D radial sequence with ultrashort echo time.

2511. Feasibility of Using Linear Combination SSFP for Lung MRI at 3 T

Atiyah Yahya1,2, Keith Wachowicz1,2, B. Gino Fallone1,2

1Department of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada; 2Department of Oncology, University of Alberta, Edmonton, Alberta, Canada

MRI of the lungs is challenging because of the low proton density and because of the large number of air-tissue interfaces which create susceptibility gradients. Lung MRI has shown to be feasible at 3 T using the HASTE sequence with parallel imaging. In this work we examine the feasibility of applying Linear Combination SSFP (LCSSFP) for lung MRI at 3 T. Experiments were conducted on a normal volunteer and lung images were acquired with both HASTE and LCSSFP. The images acquired with LCSSFP were clearer and did not suffer from blurring compared to the HASTE images.

2512. MRI as a Non-X Ray Based Imaging Alternative to Study Experimental Lung Fibrosis Induced by Bleomycin in Rats

Anna Louise Babin1,2, Catherine Cannet1, Christelle Gerard1, Clive P. Page3, Nicolau Beckmann1

1Global Imaging Group, Novartis Institutes for BioMedical Research, Basel, BS, Switzerland; 2Sackler Institute of Pulmonary Pharmacology, King’s College, London, SE1 1UL, United Kingdom; 3Sackler Institute of Pulmonary Pharmacology, King's College, London, SE1 1UL, United Kingdom

Micro-CT has been shown to be useful in characterizing anatomical changes related to lung fibrosis models in rats. However, radiation doses are an issue both in the clinics and in experimental studies, and repetitive measurements are limited. In the present work, we show that proton MRI can be used to follow longitudinally in spontaneously breathing rats the development of structural changes related to lung fibrosis induced by bleomycin administration, and thus MRI represents a non-X ray based imaging alternative to study experimental fibrosis.

2513. Non-Invasive Assessment of Mucociliary Clearance with Micron-Sized Iron Oxide Particles in Rat Lungs

Selina Bucher1, Michael Neumaier1, Sascha Koehler2, Birgit Jung3, Detlef Stiller1

1In-Vivo Imaging Unit, Dept. of Drug Discovery Support, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach, BW, Germany; 2Method Development, Bruker BioSpin MRI GmbH, Ettlingen, Germany; 3Dept. of Respiratory Diseases Research, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach, BW, Germany

Chronic obstructive pulmonary disease (COPD) is characterized by chronic inflammation and mucus production. Because an excess of mucus triggers infections, an efficient mucociliary clearance (MCC) is important. To detect therapy-induced changes in MCC, non-invasive imaging techniques are needed. We used 2D radial MRI and micron-sized iron-oxide particles to evaluate MCC in the rat lung, where four different iron-oxide particles yielded an attenuated MR signal. Clearance of 4.5 µm-sized particles occurred within one day, whereas smaller and larger particles were not cleared. Our results indicate a great potential for MRI with micron-sized iron-oxide particles to visualize and quantify MCC in patients.

2514. Fast and Robust T1 Mapping of the Human Lung at Different Sites

Jakob Kreutner1, Ruobing Yang2, Simon Triphan1,3, Martin Blaimer3, Felix Breuer3, Peter Michael Jakob1,3

1Experimental Physics 5, University of Würzburg, Würzburg, Bavaria, Germany; 2University of British Columbia, Vancouver, Canada; 3Research Center Magnetic Resonance Bavaria, Würzburg, Germany

Characterization of pathologic lung tissue necessitates a robust method for diagnosis. T1 relaxation times provide information about oxygen transfer in the lung. To demonstrate the robustness of the IR Snapshot FLASH sequence we repeatedly quantified T1 at different sites using a lung phantom made of several Gd-DTPA doped bottles. The results show an excellent reproducibility of the relaxation times.

2515. Mapping the Ventilation–perfusion Ratio in Chronic Obstructive Pulmonary Disease Using Oxygen-Enhanced MRI

Penny Louise Hubbard1,2, Geoff J. M. Parker1,2, Dave Singh3, Jørgen Vestbo3, Simon S. Young4, Eva Bondesson5, Lars E. Olsson6, Josephine H. Naish1,2

1Imaging Sciences and Biomedical Engineering, University of Manchester, Manchester, United Kingdom; 2The University of Manchester Biomedical Imaging Institute, Manchester, United Kingdom; 3Airway Pharmacology Group, School of Translational Medicine,, University Hospital of South Manchester Foundation Trust, Manchester, United Kingdom; 4AstraZeneca R & D, Charnwood, United Kingdom; 5AstraZeneca R & D, Lund, Sweden; 6AstraZeneca R & D, Mölndal, Sweden

We present a regional characterisation of the ventilation-perfusion ratio using a novel two-compartment physiological model analysis of oxygen-enhanced MRI data. A preliminary analysis of subjects with chronic obstructive pulmonary disease and age-matched healthy subjects shows how changes in T1 can be related directly to physiological parameters indicative of lung function. This novel MR method is minimally-invasive and repeatable, and reveals enhanced sensitivity to the early onset of disease than more traditional global lung function measures.

2516. Physiological Modelling of Oxygen-Enhanced MRI in the Lung

Josephine Helen Naish1,2, Geoff J M Parker1,2

1Imaging Science and Biomedical Engineering, School of Cancer and Imaging Sciences, University of Manchester, Manchester, United Kingdom; 2Biomedical Imaging Institute, University of Manchester, Manchester, United Kingdom

We present a two-compartment model of pulmonary oxygen-enhanced MRI (OE-MRI) based on known gas exchange processes in the lung. The model relates the rate of change of oxygen partial pressure to physiological parameters describing ventilation, perfusion and blood oxygen solubility and allows quantitative V/Q maps to be extracted from OE-MRI data.

2517. Fast, High Resolution T1-Mapping of the Human Lung Using an Inversion Recovery Radial Golden Angle Acquisition.

Simon Triphan1, Philipp Ehses2, Martin Blaimer1, Jakob Kreutner2, Felix Breuer1, Peter Jakob, 12

1Research Center Magnetic Resonance Bavaria e.V., Würzburg, Bayern, Germany; 2Experimentelle Physik 5, Universität Würzburg, Würzburg, Bayern, Germany

The quantification of T1 in the human lung at 1.5T using an Inversion Recovery Snapshot FLASH experiment was improved by employing an asymmetric radial readout scheme: By measuring k-space with golden angle radial projections with maximal echo asymmetry, echo times could be significantly reduced yielding improved signal from lung tissue. The acquisition scheme was combined with a KWIC-filter technique to reconstruct images at subsequent points in time along signal recovery, thereby achieving a higher temporal resolution compared to a cartesian measurement. The improved SNR and higher temporal resolution was used to calculate T1 maps at an increased spatial resolution.

2518. Feasibility Study of in Situ Lung MRE in a Porcine Model: Correlation of Shear Stiffness and Transpulmonary Pressures

Yogesh K. Mariappan1, Arunark Kolipaka1, Richard L. Ehman1, Kiaran P. McGee1

1Department of Radiology, Mayo Clinic, Rochester, MN, United States

Previous lung magnetic resonance elastography (MRE) animal experiments have indicated that it is feasible to quantitate the shear modulus of lungs with 1H MRI with the driver in direct contact with the lungs. Here, we tested the applicability of this technique in an in situ porcine model with a noninvasive mechanical driver placed on the chest wall. Further, the feasibility of this technique to measure the change in stiffness of the lung parenchyma as a function of transpulmonary pressure was also evaluated. It was found that lung stiffness can be quantified with this setup and that shear stiffness increases with increasing transpulmonary pressure.

2519. MRE of in Vivo Human Lung Parenchyma: Feasibility Study of Motion Encoding Using the Imaging Gradients with 1H MRI

Yogesh K. Mariappan1, Kevin J. Glaser1, Armando Manduca1, Richard L. Ehman1, Kiaran P. McGee1

1Department of Radiology, Mayo Clinic, Rochester, MN, United States

Application of Magnetic Resonance Elastography within the lung is challenging because of the inherently low 1H MR signal. The additional motion-sensitizing gradients inserted into the conventional MR sequence necessary for MRE results in longer echo times, further degrading the signal from lung parenchyma. We hypothesized that with appropriate manipulations, the crusher gradients of a spin echo sequence can be used for motion detection, while maintaining a short echo time. We tested this hypothesis in healthy human volunteers and found that it is feasible to detect motion within the lungs with the imaging gradients while maintaining sufficient lung tissue signal.

2520. A Novel Method Using Proton MRI and Image Registration to Investigate Relative Regional Pulmonary Compliance

Alexandra Rose Morgan1,2, Geoff J.M. Parker1,2, Marietta L.J. Scott3, Tim F. Cootes1,2, Josephine H. Naish1,2

1Imaging Science and Biomedical Engineering, School of Cancer and Imaging Sciences, The University of Manchester, Manchester, United Kingdom; 2The Biomedical Imaging Institute, The University of Manchester, Manchester, United Kingdom; 3AstraZeneca, Alderley Park, Macclesfield, United Kingdom

Current diagnosis methods in chronic obstructive pulmonary disease (COPD) are not capable of examining regional pathological changes in mechanical properties. We have developed a method for investigating relative regional pulmonary compliance using proton magnetic resonance imaging (MRI). A 2D half-Fourier acquired single-shot turbo spin-echo (HASTE) sequence was optimised for lung imaging. A mesh-based group-wise affine image registration was applied to images ordered according to respiratory cycle position. Information from the registration allowed relative regional compliance measures to be extracted and mapped over the lung. Maps show differences between healthy volunteers and COPD patients and can indicate likely regions of disease.

2521. Quantification of Bleomycin Induced Lung Injury by Means of 1H Magnetic Resonance Elastography

Kiaran P. McGee1, Richard L. Ehman1, Rolf D. Hubmayr2, David L. Levin1, Mary Breen3, Debora Rasmussen2, Yogesh K. Mariappan1

1Radiology, Mayo Clinic and Foundation, Rochester, MN, United States; 2Pulmonology & Critical Care, Mayo Clinic and Foundation, Rochester, MN, United States; 3College of Arts and Sciences, Boston College, Boston, MA, United States

Interstitial lung disease (ILD) induced end stage fibrosis is a multi phase process that includes presence of an exudate followed by either edema clearance or organization of the space filling material and fibrosis. We have applied magnetic resonance elastography (MRE) to determine if this method can differentiate between normal and those processes associated with ILD. MRE estimates of shear modulus increased following lung injury when compared to an air-filled lung suggesting that lung injury-induced restructuring of lung parenchyma results in changes to the intrinsic mechanical properties of the lung and that these changes can be quantitated with MRE.

2522. Free-Breath DCE MRI for Solitary Pulmonary Nodule with Motion Correction Based on Non-Rigid Image Registration

Junichi Tokuda1, Hatsuho Mamata1, Ritu R. Gill1, Samuel Patz1, Nobuhiko Hata1, Robert E. Lenkinski2, David J. Sugarbaker3, Hiroto Hatabu1

1Department of Radiology, Brigham and Women's Hospital, Boston, MA, United States; 2Department of Radiology, Beth Israel Deaconess Medical Center, Boston, MA, United States; 3Department of Surgery, Brigham and Women's Hospital, Boston, MA, United States

We demonstrate perfusion analysis of solitary pulmonary nodule based on free-breath DCE MRI. In DCE MRI studies, the kinetics of signal variation at lesions following the administration of the contrast agent is analyzed from time-intensity curve. Thus, it is crucial to measure the signal intensity at the corresponding regions in each frame in the time-series of images for accurate signal intensity curve analysis. However, the respiratory motion of the subjects during scans causes misalignment of anatomical regions among the frames resulting inaccuracy of time-intensity curve. In this paper, we compare perfusion analyses based on motion-compensated MRI data and manual measurement.

2523. Non-Contrast-Enhanced Pulmonary MR Imaging: Comparison of Capability for Nodule Screening Between 1.5T and 3.0T MR Systems

Keiko Matsumoto1, Yoshiharu Ohno1, Hisanobu Koyama1, Munenobu Nogami1, Daisuke Takenaka1, Yumiko Onishi1, Nobulazu Aoyama2, Hideaki Kawamitsu2, Tsutomu Araki3, Kazuro Sugimura1

1Department of Radiology, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan; 2Division of Radiology, Kobe University Hospital, Kobe, Hyogo, Japan; 3Department of Radiology, University of Yamanashi, Japan

Academic and social interest to radiation induced cancer development on CT examination is increasing in the world. Since 1997, several investigators have suggested that pulmonary MR imaging on 1.5T MR system has potential for nodule detection as substitution to CT. To the best of our knowledge, no one directly compare the capability of non-contrast-enhanced (non-CE) pulmonary MRI for pulmonary nodule detection between 1.5T and 3.0T MR systems. The purpose of this study was to prospectively and directly compare the capability of non-CE pulmonary MR imaging on 3.0T MR system for nodule detection than that on 1.5T MR system.

2524. Blood Supply and Vascularization of Lung Cancer, Studies by MRI and Optical Imaging

Gregory Jacques Ramniceanu1, Erez Eyal2, Inbal Biton3, Nava Nevo2, Raanan Margalit4, Raya Eilam-Altstadter3, Hadassa Degani1

1Biological regulation, Weizmann Institute of Science, Rehovot, Israel; 2biological regulation, Weizmann Institute of Science, Rehovot, Israel; 3Veterinary Resources, Weizmann Institute of Science, Rehovot, Israel; 4Immunology, Weizmann Institute of Science, Rehovot, Israel

The lung vasculature is composed of two systems, the bronchial and the pulmonary circulations. It is still unknown which of these two circulations, or both, contribute to the feeding of lung tumors during their progression .To answer this basic we characterize the perfusion parameters and the role of angiogenesis and interstitial fluid pressure in the lung tumors using MRI and optical imaging methods. Specifically we focus on imaging interstitial fluid pressure using a slow infusion protocol of the contrast agent.

2525. DC Gated High Resolution 3D MRI of the Human Lung Under Free Breathing

Stefan Weick1, Philipp Ehses2, Martin Blaimer2, F. A. Breuer2, P. M. Jakob1,2

1Department of Experimental Physics 5, University of Wuerzburg, Wuerzburg, Bavaria, Germany; 2Research Center for Magnetic Resonance Bavaria (MRB)

In this work, 3D Flash examinations of the human lung were performed during free respiration using the DC signal for self-gating. Short echo times (TE) are required to provide sufficiently SNR because of the short T2* of the lung tissue. It is shown that the DC signal can be acquired after the actual imaging module still providing enough quality for respiratory gating and simultaneously providing very short echo times. The maxima and minima of the DC signal were used to define threshold values for data rejection and high resolution images were reconstructed retrospectively.

2526. Dynamic MR Perfusion Imaging Vs. Time-Resolved MR Angiography Vs. MDCT: Disease Extent Assessment and Outcome Prediction for Patients with Acute Pulmonary Thromboembolism

Keiko Matsumoto1, Yoshiharu Ohno1, Hisanobu Koyama1, Yumiko Onishi1, Daisuke Takenaka1, Munenobu Nogami1, Nobukazu Aoyama2, Hideaki Kawamitsu2, Tsutomu Araki3, Kazuro Sugimura1

1Department of Radiology, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan; 2Division of Radiology, Kobe University Hospital, Kobe, Japan; 3Department of Radiology, University of Yamanashi, Japan

MDCT has become the first imaging examination in suspected APTE patients. As well as technical advances of CT, technical advances of magnetic resonance (MR) imaging make it possible to obtain time-resolved MR angiography or perfusion MR imaging (perfusion MRI) in APTE patients. We hypothesized that quantitatively assessed pulmonary perfusion parameters from contrast-enhanced perfusion MRI have potential for disease extent assessment and have predictive capability of patient outcome in APTE patients. The aim of our study was therefore to directly compare the capability for disease severity assessment and patient outcome prediction of MDCT and MR techniques in APTE patients.

2527. Exploration of Gas Flow During High Frequency Oscillated Ventilation by 19F-Gas-MRI

Janet Friedrich1, Julien Rivoire1, Alexander Wiegbert Scholz2, Maxim Terekhov1, Rainer Köbrich2, Lars Krenkel3, Claus Wagner3, Laura Maria Schreiber1

1Section of Medical Physics, Department of Diagnostic and Interventional Radiology, Johannes Gutenberg University Medical Center, Mainz, Germany; 2Department of Anesthesiology, Johannes Gutenberg University Medical Center, Mainz, Germany; 3German Aerospace Center, Göttingen, Germany

To detect convective gas flow inside the large airways during high frequency oscillated ventilation (HFOV) the fluorinated contrast gas Heptafluoropropane was used for 19F-MRI. In a first study the comparison between constant flow measurements and Computational Fluid Dynamics (CFD) simulations provided a good agreement. In a following experiment oscillated flow was applied to a lung phantom consisting of ventilation bag and long pipe. The pressure wave inside the pipe was explored point-by-point and corresponding velocities were determined. With these experiments it could be shown for the first time that flow measurement during HFOV using fluorinated contrast gas is feasible.

Hyperpolarized Gas Imaging

Hall B Thursday 13:30-15:30

2528. Comparison of Hyperpolarized 3He and 129Xe for Measurement of Absolute Ventilated Lung Volume of Rat Lungs

Matthew S. Fox1,2, Alexei Ouriadov1, William Dominguez-Viqueira1,3, Marcus Couch1,2, Giles E. Santyr1,3

1Imaging, Robarts Research Institute, London, Ontario, Canada; 2Physics and Astronomy Dept, University of Western Ontario, London, Ontario, Canada; 3Medical Biophysics, University of Western Ontario, London, Ontario, Canada

Magnetic Resonance (MR) imaging using hyperpolarized noble gases (HNG) 3He and 129Xe provides a non-invasive approach for probing both lung function and structure. Measurement of ventilated lung volumes are useful for characterizing chronic obstructive pulmonary disease, quantifying the diffusing capacity of xenon and may be useful in measuring lung mechanics such as compliance. The objective of this work was to perform 3D MR imaging in rats under similar ventilation conditions and compare measured ventilated volumes obtained from the two gases in an effort to show that 129Xe is just as accurate as 3He which has already been validated by microCT.

2529. Hyperpolarized Xenon-129 Ventilation MRI: Preliminary Results in Normal Subjects and Patients with Lung Disease

Talissa A. Altes1, John P. Mugler1, Isabel M. Dregely2, Stephen Ketel3, Iulian C. Ruset2,3, Eduard E. de Lange1, F William Hersman2,3, Kai Ruppert1

1Radiology, University of Virginia, Charlottesville, VA, United States; 2Physics, University of New Hampshire, Durham, NH; 3Xemed, LCC, Durham, NH

The purpose of this study was to assess the feasibility and currently achievable quality of hyperpolarized xenon-129 ventilation (spin density) MRI in normal subjects (n=7) and patients with asthma (n=5), chronic obstructive pulmonary disease (COPD) (n=4), cystic fibrosis (CF) (n=1), and sickle cell disease (SCD) (n=1). As seen previously with helium, the normal subjects had homogeneous ventilation with few if any ventilation defects. Focal ventilation defects were found in all patients with obstructive lung diseases. Qualitatively the hyperpolarized xenon-129 ventilation images are similar although not identical to previously acquired hyperpolarized helium-3 ventilation images in different patients with similar disease states.

2530. Synchronised Acquisition of Hyperpolarised 3He and 1H MR Images of the Lungs During the Same Breath-Hold

Jim M. Wild1, Salma Ajraoui1, Martin H. Deppe1, Steven R. Parnell1, Helen Marshall1, James Swinscoe2, Matthew Hatton2, Juan Parra-Robles1, Rob H. Ireland1

1Academic Radiology, University of Sheffield, Sheffield, Yorkshire, United Kingdom; 2Weston Park Hopital, Sheffield, United Kingdom

Combined 1H MRI of lung anatomy with hyperpolarised gas MRI of lung function has previously required acquisition of separate breath-hold exams, with separate MRI pulse sequences and dedicated RF coils, resulting in images that were not spatially registered or temporally synchronised. Here 1H anatomical and 3He ventilation MRI from human lungs were acquired in the same breath-hold using decoupled RF hardware and optimised dual acquisition MRI pulse sequences. The resulting 3He and 1H images acquired in the same breath (from volunteers and patients with lung disease), showed superior registration to those acquired in repeat breath-hold manoeuvres.

2531. Inter-Observer Reproducibility of Longitudinal Hyperpolarized Helium-3 Magnetic Resonance Imaging of Chronic Obstructive Pulmonary Disease

Miranda Kirby1,2, Lindsay Mathew1,2, Andrew Wheatley1, David G. McCormack3, Grace Parraga1,4

1Imaging Research Laboratories, Robarts Research Institute, London, Ontario, Canada; 2Medical Biophysics, The University of Western Ontario; 3Division of Respirology, Department of Medicine, The University of Western Ontario; 4Graduate Program in Biomedical Engineering, The University of Western Ontario

Here we evaluate the associations between hyperpolarized Helium-3 Magnetic Resonance Imaging (3He MRI) longitudinal changes measured in Chronic Obstructive Pulmonary Disease (COPD) ex-smokers, with SNR and inter-observer variability. Spin density images for 15 subjects were segmented to obtain ventilation defect volume (VDV) measurements at baseline and 26 months. Inter-observer reproducibility was determined for two observers; ICC= .93, COV= 26% and r2= .78 (p3T). However, SNR improvements of up to 300% have been demonstrated in rat lung at 73.5mT using Litz-wire coils. In this work the SNR for HNG MRI of rat lung was investigated theoretically and in vivo, using multi-turn Litz-wire coils at 73.5mT and compared to images obtained at 3T using 129Xe and 3He. The use of Litz-wire coils significantly reduces the advantage (from factor ten to a factor of two) of using high fields for HNG imaging of rat lungs.

2561. Quantitative Assessment of Alveolar Recruitment with Hyperpolarized Gas MRI

Kiarash Emami1, Masaru Ishii2, Stephen J. Kadlecek1, Jianliang Zhu3, Stephen Pickup1, Yi Xin1, Puttisarn Mongkolwisetwara1, Harrilla Profka1, Rahim R. Rizi1

1Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States; 2Department of Otolaryngology, Johns Hopkins University, Baltimore, MD, United States; 3Department of Surgery, University of Pennsylvania, Philadelphia, PA, United States

This study evaluates the preliminary use of HP gas diffusion MRI to assess alveolar recruitment dynamics in a healthy rat model. After a period of ventilation at zero positive end-expiratory pressure (PEEP), recruitment was studied at elevated PEEP and constant tidal volume. After recruitment, it was found that regional ADC values initially diminished and consistently recovered with the removal of elevated PEEP. It is therefore proposed that before recruitment, accumulated alveolar collapse causes the over-extension of active alveoli (high ADC); after recruitment, the fixed tidal volume is shared by the greater number of recruited alveoli (corresponding to decreased ADC).

2562. Alveolar Gas Diffusion MRI as a Function of Pulmonary Pressure

Kiarash Emami1, Stephen J. Kadlecek1, Yi Xin1, Puttisarn Mongkolwisetwara1, Harrilla Profka1, Stephen Pickup1, Jianliang Zhu2, Masaru Ishii3, Rahim R. Rizi1

1Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States; 2Department of Surgery, University of Pennsylvania, Philadelphia, PA, United States; 3Department of Otolaryngology, Johns Hopkins University, Baltimore, MD, United States

In this work, we evaluate the use of HP gas ADC measurements to assess the positive end-expiratory pressure (PEEP) dependence of alveolar recruitment in a healthy rat model. By maintaining a constant tidal volume, ADC can be decoupled from volume dependence and thus considered a measurement of average alveolar size. In general, it was found that higher ADC values correspond with large PEEP. Additionally, at any given PEEP, the end-inhale ADC value is larger than the end-exhale ADC value, supporting the theory that in low-recruitment conditions (large numbers of collapsed alveoli), active alveoli are over-inflated (yielding high ADC).

2563. Quantitative Assessment of Idiopathic Pulmonary Fibrosis with Hyperpolarized Gas MRI

Michael J. Stephen1, Kiarash Emami2, John M. Woodburn2, Elaine Chia2, Stephen J. Kadlecek2, Jianliang Zhu3, Masaru Ishii4, Milton Rossman1, Benjamin Pullinger2, Stephen Pickup2, Rahim R. Rizi2

1Department of Pulmonary and Critical Care, University of Pennsylvania, Philadelphia, PA, United States; 2Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States; 3Department of Surgery, VA Medical Center, Philadelphia, PA, United States; 4Department of Otolaryngology, Johns Hopkins University, Baltimore, MD, United States

This study demonstrates the first attempt to use hyperpolarized gas MR images of lung ventilation and apparent diffusion (ADC) in an animal model of interstitial lung disease. The efficacy of hyperpolarized 3He MRI metrics in assessing idiopathic pulmonary fibrosis (IPF) was evaluated in a bleomycin rat model. Results showed that fractional ventilation 3 weeks after bleomycin administration was significantly lower than in the control animals, and ADC measurements followed similar trends. Hyperpolarized gas MRI is a promising diagnostic for IPF and an improvement over current diagnostics in its regional sensitivity and benignancy.

2564. Regional Pulmonary Pressure Over Volume Curves of the Rat Lung Measured by Polarized 3He Magnetic Resonance Imaging

Angelos Kyriazis1,2, Ignacio Rodriguez1,2, Jose-Manuel Perez-Sanchez3, Lars E. Olsson4, Jesus Ruiz-Cabello1,2

1Universidad Complutense de Madrid, Instituto de Estudios Biofuncionales, Madrid, Spain; 2CIBER de Enfermedades Respiratorias, Spain; 3Orsay and Kremlin-Bicetre, U2R2M, Paris, France; 4DECS Imaging, AstraZeneca R&D, Mölndal, Sweden

A method to estimate regional lung volume over time based on spin-density 3He images is presented. Combining this with the tracheal pressure, regional volume over pressure is appraised. The static ROI are the left and the right lobe of the lung. Physiological parameters were calculated for the two ROI and for the whole lung. The method is proven reproducible because the measurements of the ROI of the same animal as well as the measurements of different animals agreed satisfactorily. The method may differentiate not only healthy from diseased animals but also healthy from diseased areas of the lung.

2565. In Vivo Comparison of 2D and 3D T2* in the Rat Lung Using Hyperpolarized Helium-3 MRI at 1.5 T

Kyle Hill1,2, José-Manuel Pérez-Sánchez2, Roberta Santarelli2, Mathieu Sarracanie2, Pascal Hagot2, Marlies Friese2, Xavier Maître2, Luc Darrasse2

1University of Oxford, Oxford, Oxfordshire, United Kingdom; 2Imagerie par Résonance Magnétique Médicale et Multimodalité (UMR 8081), Univ Paris-Sud, CNRS, Paris, Le Kremlin-Bicêtre, France

The T¬2* of hyperpolarized helium-3 in the lungs has shown promise in characterizing lung microstructure due to its sensitivity to local gradients caused by gas-tissue interfaces, whose abundance per unit volume changes with lung inflation and pathological modification. Despite the lung’s three-dimensional structure, most measurements of helium-3 T¬2* have been performed using projection imaging which neglects the complex microstructure’s effects. This work uses five rats in vivo to compare the T2* in a projection image with 3D imaging and shows that 3D is necessary to detect statistically different local phenomena that may not be apparent in projection imaging.

2566. Gravity Dependent Ventilation of Rats Measured by Hyperpolarised Helium MRI and Electric Impedence Tomography

Marlies Elly Joy Friese1, Kimble R. Dunster, 12, Gary J. Cowin1, Deming Wang1, Graham Galloway1, John Fraser3,4, Andreas Schibler, 4,5

1Centre for Magnetic Resonance, The University of Queensland, Brisbane, Queensland, Australia; 2Medical Engineering Research Facility,, Queensland University of Technology, Brisbane, Queensland, Australia; 3Paediatric Intensive Care Unit,, Mater Children’s Hospital, Brisbane, Queensland, Australia; 4Critical Care Research Group, The Prince Charles Hospital, Brisbane, Queensland, Australia; 5Paediatric Intensive Care Unit, Mater Children’s Hospital, Brisbane, Queensland, Australia

Gravity-dependent ventilation distribution was investigated in using both hyperpolarised helium-3 magnetic resonance imaging (HP3He MRI) and electrical impedance tomography (EIT). Time averaged EIT data and HP3HeMRI images of apnoea showed ventilation distribution in rats to be gravity dependent, whereas regional filling characteristics are dependent on anatomy. HP3He MRI and EIT data agree where they can be compared. HP3He MRI provides data on real geometry which EIT cannot as EIT tomograms are reconstructed to a circular image. Dynamic imaging of the breathing cycle with HP3He is still needed to make a full comparison of the two methods.

2567. Respiratory Impedance in a Mouse Model of Asthma Using Hyperpolarized 3He MR Imaging

Suryanarayanan Sivaram Kaushik1, John Nouls1, Erin Potts2, Zackary Cleveland1, W Michael Foster2, Bastiaan Driehuys1

1Center for In-Vivo Microscopy, Duke University Medical Center, Durham, NC, United States; 2Pulmonary and Critical Care Medicine, Duke University Medical Center, Durham, NC, United States

The broncho-constriction and inflammation associated with asthma contributes to increased airway impedance. This impedance is typically measured using global respiratory mechanics techniques such as FlexiVent. However, the time course of broncho-constriction can also be directly visualized using hyperpolarized (HP) 3He MRI. This imaging-based technique provides a time-dependent method for quantifying central airway impedance and may be useful to assess the regional contributions to globally measured impedance. Here, we discuss the method we used in obtaining the upper airway impedance during a Methacholine (Mch) challenge, in a mouse model of asthma.

2568. Relaxation of Hyperpolarized 129Xe in a Flexible Gas Reservoir

Harald E. Möller1,2, Zackary I. Cleveland2, Laurence W. Hedlund2, Bastiaan Driehuys2

1Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany; 2Center for In Vivo Microscopy, Duke University Medical Center, Durham, NC, United States

In experiments involving repeated deliveries of hyperpolarized (HP) gas, the delivered magnetization is not constant due to unavoidable relaxation during HP gas storage. Moreover, the spin-lattice relaxation time, T1R, inside flexible plastic bags, which often serve as HP gas reservoirs, is not constant. The change of T1R of HP 129Xe in a deflating bag can be quantitatively described by a model based on simple spherical geometry and the kinetic theory of gases to account for relaxation mechanisms in the bulk gas and on the container walls. Results might be used for optimizing signal utilization and improving the point-spread function.

2569. Hyperpolarized 3He Image Feature Analysis in Asthmatics

Nicholas James Tustison1, Talissa A. Altes2, Gang Song1, Eduard E. de Lange2, John P. Mugler III2, James C. Gee1

1Radiology, University of Pennsylvania, Philadelphia, PA, United States; 2Radiology, University of Virginia, Charlottesville, VA, United States

We analyze features extracted from hyperpolarized helium-3 ventilation images in asthmatic and normal populations and quantify their discriminatory abilities in characterizing clinical diagnosis relative to spirometric features.

2570. Retrospective Bias Correction of Hyperpolarized 3He MRI of the Lung

Nicholas James Tustison1, Talissa A. Altes2, G. Wilson Miller2, Eduard E. de Lange2, John P. Mugler III2, James C. Gee1

1Radiology, University of Pennsylvania, Philadelphia, PA, United States; 2Radiology, University of Virginia, Charlottesville, VA, United States

We present an open source bias correction algorithm based on the popular N3 algorithm and demonstrate its superior performance for nonuniform intensity correction in hyperpolarized helium-3 lung images.

2571. Hyperpolarized 3He Magnetic Resonance Image Registration Tools for Longitudinal and Multi-Modality Studies

Lindsay Mathew1,2, Usaf Aladl1, Aaron Fenster1,2, Grace Parraga1,2

1Imaging Research Laboratories, Robarts Research Institute, London, Ontario, Canada; 2Medical Biophysics, The University of Western Ontario, London, Ontario, Canada

Hyperpolarized 3He MRI has shown promise as a treatment planning tool for lung cancer. Current barriers to the application of this technology include a lack of accurate image registration techniques. Registration of longitudinally acquired 3He MRI scans and 3He MRI to CT will allow for both detection of regional changes in lung function, and determination of ventilation defect pathology. In this study accuracy and variability of 3He MRI registration techniques were evaluated from a dataset consisting of subjects scanned longitudinally at our center. The Fiducial Localization Error and Fiducial Registration Error were evaluated as metrics of registration accuracy and precision.

2572. Quantitative Evaluation of Hyperpolarized Gas Retention in the Lungs During Time Resolved 3D MRI

Jionghan Dai1, Eric Peterson2, James H. Holmes3, Sean B. Fain1,4

1Medical Physics, University of Wisconsin - Madison, Madison, WI, United States; 2Biomedical Engineering, University of Wisconsin - Madison, Madison, WI, United States; 3Applied Science Lab, GE Healthcare, Madison, WI, United States; 4Radiology, University of Wisconsin - Madison, Madison, WI, United States

This work seeks to provide a quantitative regional measure of gas retention in the lung. A 3D multi-echo projection acquisition is used, accompanied with an iterative HYPR reconstruction to provide a time resolved 3D image series. Post exhalation images are used to generate quantitative maps of gas retention. To summarize, this work presents potential new methods to characterize the gas retention under forced exhalation using hyperpolarized noble gas MRI.

2573. B1 Self-Calibration for Artifact Removal in Radial Hyperpolarised 3He Lung Imaging

Helen Marshall1, Salma Ajraoui1, Martin Deppe1, James M. Wild1

1Academic Unit of Radiology, University of Sheffield, Sheffield, South Yorkshire, United Kingdom

In hyperpolarised 3He lung MRI the transverse signal decays with each RF excitation, imposing a k-space filter on the acquired data. For radially acquired data this filter causes streaking, angular shading and loss of spatial resolution in the images. Radial acquisition samples the centre of k-space with every projection, so tracking the signal decay. The inverse of this decay function was used to retrospectively compensate the data leading to improved image quality. The average flip angle per slice was calculated from the radial data and found to correspond well with conventional flip angle maps providing a means of B1 self-calibration.

2574. Performance of Three Transmitter Calibration Methods for Hyperpolarized Gas MRI in the Presence of B0 and B1 Inhomogeneity

Kun Qing1, Grady Wilson Miller2, John Philip Mugler, 12

1Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, United States; 2Department of Radiology, University of Virginia, Charlottesville, VA, United States

A low-flip-angle, phase-based method for calibrating the transmitter voltage for hyperpolarized gas MRI has been presented in previous studies. This work introduces two optimized versions of the phase-based method, and evaluates their performance in the presence of B0 and B1 inhomogeneities compared to that for an amplitude-based method. Results show that the accuracy of all three methods is affected by significant B1 inhomogeneity; for significant B0 inhomogeneity, the amplitude-based method is robust while the phase-based methods are very sensitive, particularly at relatively low flip angles.

2575. Proton Acquisition with Variable Flip Angle to Simulate and Optimized Hyperpolarized 3He MRI with Parallel Acquisition

Julien Rivoire1, Maxin Terekhov1, Laura Maria Schreiber1

1Department of Diagnostic and Interventional Radiology, Section of Medical Physics, Johannes Gutenberg University Medical Center, Mainz, Germany

To employ the scanner’s software computational capabilities and to simulate the complete measurement process without using expensive hyperpolarized gas, we developed the dedicated 1H MRI acquisition protocol using variable flip angle pulse sequence to simulate hyperpolarized magnetization decay. The protocol was used to study the effect of different space sampling ordering on images acquired with parallel acquisition techniques. Via the calculation of point-spread-function, the effects of the trajectories were quantitatively compared.

2576. Hyperpolarized Steady-State Free Precession with Variable Flip Angles (BSSFP-VFA)

Martin H. Deppe1, Jim M. Wild1

1Academic Radiology, University of Sheffield, Sheffield, Yorkshire, United Kingdom

In imaging of hyperpolarized nuclei, balanced Steady-State Free Precession (bSSFP) sequences present a high SNR alternative to the most commonly used Spoiled Gradient Echo (SPGR) sequences. Because hyperpolarized nuclei are not at thermal equilibrium, the longitudinal magnetization does not recover during an imaging experiment, but decays to a negligible value with T1. This work presents analytical expressions for variable flip angle schedules that maintain constant transverse magnetization, optimizing the effective k-space filter imposed by decay of hyperpolarization, and hence reducing image blurring. The validity of the obtained expression is demonstrated in phantom experiments.

2577. High-Efficiency Continuous Production of Hyperpolarized 129Xe Using Line-Narrowed Diode Lasers and Optimized Cell for High Concentration of Optically Pumped Rubidium

Mineyuki Hattori1, Takashi Hiraga2, Morio Murayama3, Norio Ohtake3

1Photonics, AIST, Tsukuba, Ibaraki, Japan; 2Photonics, AIST, Ikeda, Osaka, Japan; 3Toyoko Kagaku Co., Ltd., Kawasaki, Kanagawa, Japan

A compact flow-through-type apparatus for the high-efficiency continuous production of hyperpolarized 129Xe using line-narrowed diode lasers and an optimized cell for obtaining a higher rubidium vapor concentration at a higher temperature (~220 oC) was developed.

2578. McConnell-Bloch Modeling of HyperCEST with Xenon Biosensors

Richard Matthew Ramirez1, Todd K. Stevens1, Monica A. Smith2, David E. Wemmer1, Alexander Pines1

1Department of Chemistry, University of California, Berkeley, Berkeley, CA, United States; 2Biophysics Graduate Group, University of California, Berkeley, Berkeley, CA, United States

The McConnell-Bloch equations were modified to account for the use of hyperpolarized xenon, and then applied to fit experimental data obtained from hyperCEST experiments in which Xe exchanges into and out of a supramolecular host. A variety of physical parameters were tested and rate constants for the reversible exchange were determined, which are important in determining the amount of contrast generated from these agents.

2579. Metastability Exchange Optical Pumping of 3He at 1.5T for a In-Situ Polariser

guilhem Collier1, Anna Nikiel1, Tadeusz Palasz1, Bartek Glowacz1, Mateusz Suchanek2, Zbigniew Olejniczak3, Tomasz Dohnalik1

1M. Smoluchowski Institute of Physics, Jagiellonian University, Krakow, Malopolska, Poland; 2Department of Physics, Agricultural University, Krakow, Poland; 3Institute of Nuclear Physics, Polish Academy of Sciences, Krakow

The feasibility of building an in situ high field polariser of 3He using the Metastability Exchange Optical Pumping (MEOP) technique is studying here. The first results obtained with different closed cells of 3He show the possibility to produce hyperpolarised gas up to 30% at 267 mbar and 67% at 32 mbar with a volume nagnetization production never obtained yet.

2580. Pressure Dependent Signal Enhancement in Hyper-CEST

Wolfgang Kilian1, Lorenz Mitschang1, Christian Freund2, Andreas Schlundt2

1Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, 10587 Berlin, Germany; 2Leibnizinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Str. 10, 13125 Berlin, Germany

The so called hyper-CEST method promises tremendous potential on molecule-specific MR imaging using hyperpolarized 129Xe caged in functionalized cryptophane cages. Here we present a model which allows for an optimization of the hyper-CEST sensitivity in biosensor applications, by variation of the xenon concentration in the solution. To evaluate the model we have performed hyper-CEST measurements on samples with 5 μM and 0.5 μM biosensor concentrations and varied the dissolved xenon concentration. This comparison shows that 50 nM biosensor concentrations should be detectable within a volume of 1 ml with high sensitivity.

Hepato-Biliary & Liver

Hall B Monday 14:00-16:00

2581. Fat Content Quantification Errors Using Multiple Gradient Echo Imaging: A Phantom and Simulation Study

Benjamin Leporq1, Hélène Ratiney1, Sophie Cavassila1, Frank Pilleul2, Olivier Beuf1

1Université de Lyon, Creatis-LRMN, CNRS UMR 5220, Inserm U630, INSA-Lyon, Université Lyon 1, Villeurbanne, France; 2Université de Lyon, Creatis-LRMN, CNRS UMR 5220, Inserm U630, INSA-Lyon, Université Lyon 1, Hospices Civils de Lyon, Lyon, France

In the past decade, the incidence increase of obesity, diabetes and lipid metabolism disorders involved an epidemic increase of Non-Alcoholic Fatty Liver Diseases (NAFLD) in the occidental population. Because NAFLD can evolve into Non-Alcoholic Steato-Hepatitis (NASH) and may lead to liver fibrosis up to cirrhosis, a clinical follow-up of NAFLD would be very valuable. This work investigated fat content quantification error using different models based on multiple gradient echo imaging and presents some computer simulations, phantom study and examples of in-vivo application. Multiple gradient echo acquisitions with two different flip angles associated with a model correcting for T1 saturation and T2* decay appears to be a simple but effective non-invasive method available on all clinical systems to monitor patients with chronic liver diseases.

2582. Improvements in Hepatic Stiffness Assessment with 3-D/3-Axis MR Elastography

Meng Yin1, Kevin J. Glaser1, Jun Chen1, Jayant A. Talwalkar2, Armando Manduca1, Richard L. Ehman1

1Department of Radiology, Mayo Clinic, Rochester, MN, United States; 2Division of Gastroenterology, Mayo Clinic, Rochester, MN, United States

One advantage of liver MR elastography (MRE) over biopsy or ultrasound-based transient elastography is its ability to reduce sampling errors by measuring liver stiffness over a large portion of the liver. While existing 2-D or localized approaches yield valid results in a substantial part of the volume, a full 3-D/3-axis wave analysis is required for valid measurements of stiffness throughout the entire liver. This investigation compares a 2-D and a 3-D approach for liver MRE and demonstrates that 3-D MRE analysis improves the homogeneity of hepatic stiffness estimates.

2583. A Software Tool for Volume Registration and Atlas-Based Segmentation of Human Fat-Water MRI Data in Longitudinal Studies

Anand Arvind Joshi1, H Harry Hu2, Michael Goran3, Richard Leahy2, Arthur Toga1, Krishna Nayak2

1Department of Neurology, David Geffen School of Medicine, UCLA, Los Angeles, CA, United States; 2Ming Hsieh Department of Electrical Engineering, University of Southern California, Los Angeles; 3Keck School of Medicine, University of Southern California, Los Angeles, CA

Obesity continues to be a worldwide epidemic. Accurate quantification of subcutaneous and visceral adipose tissue depot volumes and the degree fat infiltration in the liver, the pancreas, skeletal muscle, and the kidneys, are important endpoints in determining the efficacy of therapeutic and interventional measures against obesity. For example, in longitudinal studies, measures are taken at multiple time points in each subject to determine the effects of diet, exercise, lifestyle modifications, and surgery, on fat quantity and distribution. In this work, we present an automated atlas-based tool for performing 3D volume registration and segmentation of abdominal adipose tissue depots and organs.

2584. Orthotopic Liver Transplantation: MRI Based Measurement of Donor Graft Steatosis, Graft Performance and Outcome.

David John Lomas1, Richard T. Black1, Andrew J. Patterson1, Kieren G. Hollingsworth1, Susan Davies2, Graeme J. Alexander3, Mike E. Allison3, Neville V. Jamieson4, Alex E. Gimson3, Raaj K. Praseedom4, Chris J. Watson4

1Radiology, University of Cambridge & Addenbrooke's Hospital, Cambridge, Cambridgeshire, United Kingdom; 2Pathology, University of Cambridge & Addenbrooke's Hospital, Cambridge, Cambridgeshire, United Kingdom; 3Hepatology, University of Cambridge & Addenbrooke's Hospital, Cambridge, Cambridgeshire, United Kingdom; 4Surgery, University of Cambridge & Addenbrooke's Hospital, Cambridge, Cambridgeshire, United Kingdom

The results of rapid MRI based measurement of donor graft steatosis immediately prior to orthotopic liver transplantation in 49 patients were correlated with surgical and histopathology estimates, first week graft performance and 3 and 12 month outcomes. MR measurements correlated significantly with the other steatosis estimates but did not correlate with early serum performance markers. Both MRI and pathology estimates indicated significantly increased graft steatosis in those grafts failing at 3 months but not at 12 months. Such MRI based measurements may be a valuable tool for further investigating the impact of graft steatosis on transplant outcomes.

2585. Effect of Intravenous Gadolinium on Estimation of Liver Stiffness with MR Elastography

Sudhakar Kundapur Venkatesh1, Lynette Li San Teo1, Bertrand Wei Leng Ang1, Richard L. Ehman2

1Diagnostic Imaging, National University Health System, Singapore, Singapore; 2Radiology, Mayo Clinic, Rochester, MN, United States

MR Elastography is currently the most accurate non-invasive technique for assessment of liver fibrosis. In this study, we investigated whether administration of gadolinium for routine MRI studies affects the stiffness values estimated. Our study results show that intravenous gadolinium does not affect stiffness values estimation and diagnostic performance of MRE for detection of liver fibrosis.

2586. Non-Invasive Detection of Liver Fibrosis- A Comparison Study Between MR Elastography and Diffusion Weighted MR Imaging

Sudhakar Kundapur Venkatesh1, Lynette Li San Teo1, Bertrand Wei Leng Ang1, Seng Gee Lim2, Aileen Wee3

1Diagnostic Imaging, National University Health System, Singapore, Singapore; 2Gastroenterology and Hepatology, National University Health System, Singapore, Singapore; 3Pathology, National University Health System, Singapore, Singapore

Liver biopsy is the gold standard for diagnosis of liver fibrosis, however has related risks and costs. A non-invasive marker of liver fibrosis is therefore desirable. Currently MRE and DWI are most promising tests for detection of liver fibrosis without the use of gadolinium based contrast agents. We performed a study to compare the performance of DWI and MRE for detection of liver fibrosis. Our study shows that MRE is more accurate than DWI for detection of all grades of fibrosis and in particular clinically significant fibrosis.

2587. 7T Human Liver Imaging Using Microstrip Surface Coil

Yong Pang1, Bing Wu2, Chunsheng Wang2, Daniel Vigneron2,3, Xiaoliang Zhang2,3

1Radiology and Biomedical imaging, University of California San Francisco, San Francisco, CA , United States; 2Radiology and Biomedical imaging, University of California San Francisco, San Francisco, CA, United States; 3 UCSF/UC Berkeley Joint Graduate Group in Bioengineering, San Francisco & Berkeley, CA, United States

MRI can provide clinically-valuable images for hepatic diseases and has become the most accurate noninvasive method in evaluating liver lesions. With the development of high and ultrahigh field MRI, liver images may be acquired within breath-hold period using very short TE, essentially reducing scanning time and motion artifacts. However, B1 variation can cause significant problems at high field. In this work, T1 weighted human liver images are acquired using a fast gradient echo sequence and a λ/2 microstrip surface coil on GE whole body 7T scanner. Preliminary data demonstrates the feasibility of human liver imaging at 7 Tesla.

2588. Assessment of Chemical Exchange Saturation Transfer Effects in Liver Tissue at 7T

Kejia Cai1, Mohammad Haris1, Anup Singh1, Santosh Gaddam1, Dania Daye1, Kalli Grasley1, Gerald Zsido II1, Hari Hariharan1, Ravinder Reddy1

1CMROI, Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States

The objective of the present study was to determine the chemical exchange saturation transfer (CEST) effects of water signal in normal and pathological liver samples on 7T MR clinical scanner, ex-vivo. In all liver tissue samples, the z-spectra showed a dip around ~2.75ppm downfield to the bulk water resonance, suggestive of exchangeable proton at this frequency. The pathological tissues showed significantly higher CEST contrast compared to normal. We are hypothesizing that the formation of liver fibrosis in various disease conditions may be expressing metabolites with exchanging groups resonating at the observed CEST frequency.

2589. Cost Function Guided Image Based B0 Shimming at 3T for Efficient Fat Suppression in Liver and Prostate Imaging

Jeroen Cornelis Siero1, Marielle E. Philippens2, Arjan Willem Simonetti3, Johannes Marinus Hoogduin1, Peter R. Luijten4

1Brain Division, University Medical Center Utrecht, Utrecht, Netherlands; 2Radiotherapy, University Medical Center Utrecht; 3Philips Healthcare, Best, Netherlands; 4Radiology, University Medical Center Utrecht, Utrecht, Netherlands

The potential of cost function guided shimming was shown at 3T for finding optimal shim fields that minimize B0 inhomogeneities on a user-defined region of interest while confining the B0 inhomogeneities outside this ROI. Experiments and simulations using the hybrid shimming approach show the possibility to control frequency selective fat suppression in abdomen and pelvic imaging while maintaining good B0 homogeneity in the region of interest.

2590. Reduction in Dielectric Shading in Liver on Clinical 3T Parallel Transmission MR System

Trevor Andrews1, Jimmy S. Ghostine2, Jay V. Gonyea2, George M. Ebert2, Steven P. Braff3, Christopher G. Filippi3

1Philps Healthcare, Cleveland, OH, United States; 2Radiology, Fletcher Allen Health Care-UVM, Burlington, VT, United States; 3Radiology, Fletcher Allen Health Care-University of Vermont School of Medicine, Burlington, VT, United States

Dielectric shading artifacts impair image quality for body applications at 3T and hamper clinical acceptance of 3T body imaging. Parallel radiofrequency (RF) excitation, an application of parallel imaging to transmission, at 3T, reduces dielectric shading by adjustment of RF transmission signals enabling RF “shimming” There is the added benefit of more uniform specific absorption ratio (SAR), and shorter acquisition times. Our purpose was to quantitatively validate a novel acquisition method for reducing dielectric shading using parallel transmission techniques in clinical 3T abdominal MRI. In most cases, shading artifact was nearly eliminated, and with B1 shimming this was significantly lower.

2591. Continuously Moving Table MR Imaging at 3T: A Comparison to 1.5T

Ute Ariane Ludwig1, Maxim Zaitsev1, Sandra Huff1

1Department of Diagnostic Radiology, Medical Physics, University Hospital Freiburg, Freiburg, Germany

Since the introduction of continuously moving table (CMT) imaging, metastases screening can easily performed in the whole body on clinical routine scanners. In this abstract, we want to demonstrate the feasibility of CMT techniques at higher field strengths. Clinical relevant imaging sequences have been adapted for imaging at 3T and evaluated on volunteers. Signal-to-noise ratio and contrast-to noise ratio have been compared to 1.5T. Future studies will combine CMT protocols for metastases screening with other MR modalities like perfusion imaging or spectroscopy, which benefit from the signal increase at higher field strengths.

2592. Flip Angle Optimization with Hepatobiliary Contrast Agents at 3T

Sharon Lisa D'Souza1, Alex P. Frydrychowicz1, Karl K. Vigen1, Scott K. Nagle1, Scott B. Reeder2

1Radiology, University of Wisconsin, Madison, WI, United States; 2Radiology, Medical Physics, Biomedical Engineering, and Medicine, University of Wisconsin, Madison, WI, United States

Gadolinium based contrast agents Gd-EOB-DTPA and Gd-BOPTA have hepatobiliary excretion and tremendous utility for liver lesion characterization and biliary imaging with T1 weighted imaging. Unfortunately, most T1 weighted sequences are not optimized for maximizing CNR in delayed phase hepatobiliary imaging. The purpose of this study was to perform flip angle optimization at 3.0T for delayed hepatobiliary phase imaging as part of a cross-over study comparing Gd-EOB-DTPA and Gd-BOPTA. Data show that imaging at 40-45° FA with 0.05mmol/kg Gd-EOB-DTPA at 20 minutes and 20-25° FA with 0.1mmol/kg Gd-BOPTA provides optimal CNR behavior to visualize the liver and bile ducts.

2593. Effects of a Single Intravenous Dose of Estradiol-17β D-Glucuronide on Biliary Excretion: Assessment with Gadoxetate DCEMRI

Jose Ulloa1, Simone Stahl2, Carsten Liess1, Jonathan Bright3, Angela McDermott2, Neil Woodhouse1, Jane Halliday1, Arvind Parmar1, Guy Healing2, Gerry Kenna2, Andrew Holmes1, Hervé Barjat1, John Waterton1, Paul Hockings1

1Translational Sciences, Astrazeneca, Macclesfield, Cheshire, United Kingdom; 2Safety Assessment, Astrazeneca, Macclesfield, Cheshire, United Kingdom; 3Discovery Statistics, Astrazeneca, Macclesfield, Cheshire, United Kingdom

Cholestasis is an important mechanism that can result in drug induced liver injury, a recurrent cause of attrition of new drug candidates. In rats, transporters Oatp1 and Mrp2 mediate liver uptake and clearance of gadoxetate, a hepatobiliary contrast agent used to characterise focal liver lesions. Estradiol-17β D-glucuronide (E217G) induces acute but transient cholestasis in rats through impairment of Mrp2 and Bsep function. The aim of this work was to assess whether characterisation of the kinetics of gadoxetate excretion can detect transient cholestasis induced by E217G. Results suggest this method can be used to investigate inhibition of transporters mediating biliary excretion.

2594. 3D-Liver Perfusion MR Imaging with MS-325 Blood Pool Contrast Agent to Evaluate Liver Fibrosis

Benjamin Leporq1, Olivier Beuf1, Denis Grenier1, Frank Pilleul2

1Université de Lyon, Creatis-LRMN, CNRS UMR 5220, Inserm U630, INSA-Lyon, Université Lyon 1, Villeurbanne, France; 2Université de Lyon, Creatis-LRMN, CNRS UMR 5220, Inserm U630, INSA-Lyon, Université Lyon 1, Hospices Civils de Lyon, Lyon, France

Liver fibrosis is an important cause of mortality and morbidity in patients with chronic liver. A non invasive technique to perform an early detection and a clinical follow-up of liver fibrosis is still needed. The objectives of this study was to evaluate estimated-perfusion parameters based on 1.5T-MR dynamic acquisition with the MS-325 paramagnetic blood pool agent for liver fibrosis diagnosis in comparison with histological findings. Dynamic 3D MRI was performed with a continuous free-breathing acquisition followed by a rigid-images registration. A 5-parameters dual input one compartment model was used to estimate quantitative perfusion parameters. Sixteen patients with chronic liver diseases were prospectively enrolled. Hepatic Perfusion Index and portal blood flow were found relevant parameters to discriminate between F2, F3 and F4 METAVIR stages (p 5 mmHg) and diffusion coefficients estimated using monoexponential as well as biexponential diffusion models. This result suggests a high potential of DWI parameters as surrogate markers for IFP.

2780. Multi-Modal Assessment of Longitudinal Growth of Liver Metastases in a Mouse Model of Colon Carcinoma

Prachi Pandit1,2, Samuel M. Johnston1,2, Yi Qi2, Jennifer Story3, Beth Hollister3, G A. Johnson1,2

1Biomedical Engineering, Duke University, Durham, NC, United States; 2Center for In Vivo Microscopy, Duke University, Durham, NC, United States; 3Piedmont Research Center, Morrisville, NC, United States

In this work we present a longitudinal, multi-modality study to monitor the growth of liver metastases in mouse model of colon carcinoma. We have compared the relative merits of using high-field T2-weighting MRI and contrast-enhanced microCT as a preclinical cancer imaging technique in free-breathing mice. The advantages of microCT lie in the fast acquisition of high-resolution isotropic datasets. MRI, on the other hand has higher contrast resolution, and requires neither contrast injection nor radiation dose. Both techniques, ungated MRI and respiratory-gated MicroCT, perform well in the presence of motion, and are sufficiently fast and non-invasive to allow repeated scanning.

2781. Imaging of Tumor Angiogenesis in a Novel Skin Chamber Using MRI and Optical Imaging

Tobias Bäuerle1, Clarissa Gillmann2, Reiner Umathum1, Margareta M. Müller3, Michal Neeman4, Wolfhard Semmler2, Michael Bock1

1Medical Physics in Radiology, German Cancer Research Center, Heidelberg, Germany, Germany; 2Medical Physics in Radiology, German Cancer Research Center , Heidelberg, Germany, Germany; 3Tumor- and Microenvironment, German Cancer Research Center, Heidelberg, Germany, Germany; 4Biological Regulations, The Weizmann Institute of Science, Rehovot, Israel

Tumor angiogenesis in animal models is often visualized using optical imaging or MRI. In this work we present a subcutaneous skin chamber for simultaneous optical and MR imaging to study the tumor-induced growth of blood vessels in vivo. The fully MR-compatible chamber features an optical window, and can be combined with a dedicated external loop coil.

2782. MR Characterization of the Tumor Microenvironment After Arsenic Trioxide Treatment: Evidence for an Effect on Oxygen Consumption That Radiosensitizes Solid Tumors

Caroline Diepart1, Oussama Karroum, Julie Magat, Olivier Feron, Bénédicte Jordan, Bernard Gallez

1UCL, Brussels, Belgium

As2O3 inhibits mitochondrial respiratory function in human leukemia cells. We hypothesized that As2O3 could also be an important modulator of tumor oxygenation by affecting the oxygen consumption of solid tumors. We observed an increase in tumor pO2 in two tumor models after arsenic treatment using oximetry techniques based on EPR and 19F NMR relaxometry. This effect was explained by a decrease in oxygen consumption of the tumors. Finally, the irradiation of tumors showed a regrowth delay that was significantly increased in arsenic-treated mice. As2O3 is an important modulator of pO2 by decreasing oxygen consumption and enhances the response of tumors to radiotherapy.

2783. Improving Tumour ADC Estimates and Elucidating Tumour Heterogeneity Using Adaptive Bayesian Markov Random Field Monte Carlo

Simon Walker-Samuel1, Matthew Orton1, Jessica K R Boult1, Simon P. Robinson1

1Cancer Research UK & EPSRC Cancer Imaging Centre, The Institute of Cancer Research, Sutton, Surrey, United Kingdom

A method for improving ADC estimates using an adaptive Bayesian Markov random field analysis is described and evaluated using simulations and in vivo tumour models. Via the sharing of information between neighbouring pixels, the uncertainty and error in ADC estimates are significantly reduced by a factor of up to 80%. The approach also enables the segmentation of homogeneous tissue components and a novel measure of tissue (tumour) heterogeneity is described.

2784. Serial Multiparametric MRI in Study Design and Response Evaluation of Radiation and Antiangiogenic Therapy in an Intracranial Murine Glioblastoma Model

Caroline Chung1, Warren Foltz1, Petra Wildgoose1, Kelly Burrell2, Patricia Lindsay1, Andrea Kassner3, David Jaffray1, Gelareh Zadeh4,5, Cynthia Menard1

1Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ontario, Canada; 2SickKids' Hospital, Toronto, Ontario, Canada; 3SickKids Hospital, Toronto, Onatario, Canada; 4Brain Tumour Research Centre, Toronto, Ontario, Canada; 5Toronto Western Hospital, Canada

This study demonstrates feasibility of using multiparametric micro-MRI to overcome the challenges of intracranial mouse tumour models. Baseline T2w images were used to select mice with visible tumours and to stratify mice to treatment arms based on tumour size. Serial multiparametric MRI was used to measure tumour growth and vascular changes on DCE-MRI (iAUC60) with radiation (RT) and/or sunitinib (SU) anti-angiogenic treatment. Early rises in iAUC60 were noted following both RT and SU monotherapy, while the combination of RT and SU resulted in an early significant decrease in iAUC60. These early measured DCE-MRI changes show promise as useful early biomarkers for treatment response.

2785. A Multiple Coil Array Approach for Mouse Brain Tumor Imaging

Lilia V. Ileva1, Marcelino Bernardo2,3, Diane Palmieri4, Patricia Steeg4, Joseph Kalen1, Peter Choyke2

1Small Animal Imaging Program, SAIC-Frederick, NCI-Frederick, Frederick, MD, United States; 2Molecular Imaging Program, NCI, NIH, Bethesda, MD, United States; 3Imaging Physics, SAIC-Frederick, NCI-Frederick, Frederick, MD, United States; 4Laboratory of Molecular Pharmacology, NCI, NIH, Bethesda, MD, United States

Multiple mouse MRI is of critical importance in preclinical cancer research when longitudinal studies with multiple animals is required. This work presents a four-mouse brain imaging coil system and its application in the development of a breast cancer brain metastasis mouse model. The four-mouse SENSE array is integrated in a single platform with physiological support system. Six imaging sessions on 18 mice were performed weekly to monitor the initiation and progression of the brain metastases. The usage of the multiple mouse brain coil system significantly improved the efficiency of MRI studies involving serial imaging of multiple small animals.

2786. 13C HR MAS MRS Reveals Differences in the Glucose Metabolism Between Two Breast Cancer Xenograft Models with Different Gene Expression Pattern

Maria Tunset Grinde1, Siver Andreas Moestue1, Øystein Risa1, Olav Engebraaten2, Ingrid Susann Gribbestad1

1Department of Circulation and Medical Imaging, NTNU, Trondheim, Norway; 2Department of Tumor Biology, Cancer Research Institute, Oslo University Hospital, Oslo, Norway

13C HR MAS MR spectroscopy has been used to study two breast cancer xenograft models, representing a human luminal-like and a basal-like genetic profile. The models received a bolus injection of [1-13C]glucose and the conversion from glucose to lactate and alanine was observed 10 or 15 minutes after. The luminal-like model showed a significantly lower ratio of glucose/alanine and glucose/lactate compared to the basal-like model. This can be explained by a lower uptake of glucose and/or a higher rate of glucose metabolism towards alanine and lactate in the luminal-like compared to the basal-like model.

2787. DMSO as a Potential Contrast Agent for Brain Tumours

Teresa Delgado-Goni1,2, Rui V. Simoes, 12, Milena Acosta, 12, Juana Martin-Sitjar1,2, Silvia Lope-Piedrafita, 2,3, Carles Arus1,2

1Bioquimica i Biologia Molecular, Universitat Autonoma of Barcelona, Cerdanyola del Valles, Barcelona, Spain; 2CIBER-BBN, Zaragoza, Spain; 3Servei de Ressonancia Magnetica Nuclear, Universitat Autonoma of Barcelona, Cerdanyola del Valles, Barcelona, Spain

We describe here the application of Dimethyl Sulfoxide (DMSO) as a potential contrast agent for brain tumour imaging. DMSO crosses the blood-brain-barrier, but its differential wash-out kinetics produces a clear contrast enhancement in mouse brain glioblastoma compared to nearby/peritumoral brain parenchyma, measured by SV MRS and MRSI sequences.

2788. Predicting and Monitoring Response to Chemotherapy by Benzamide Riboside in Hepatocellular Carcinoma Using Apparent Diffusion Coefficient of Water

Andriy Babsky1, Shenghong Ju2, Beena George, Stacy Bennett, Mingsheng Huang, Hiremagalur N. Jayaram, Gordon McLennan, Navin Bansal

1Radiology, Indiana University, Indianapolis, IN, United States; 2Indiana University

Implantation of N1S1 cells in the rat liver can be used as an intrahepatic hepatocellular carcinoma (HCC) model for pre-clinical study of transarterial therapy with the apoptotic agent benzamide riboside (BR). Water apparent diffusion coefficient (ADC) in HCC was higher than in nearby normal liver tissue. Intrahepatic infusion of BR was a semi-effective treatment of HCC in rats. BR therapy did not change the water ADC value, regardless of tumor sensitivity. A higher initial ADC level could be a promising sign for effective BR treatment, and in contrast, tumors with a lower initial ADC value are most likely to be resistant to BR-treatment.

2789. Dynamic Contrast-Enhanced Magnetic Resonance Imaging Reveals Differences in Xenografts with Luminal Like and Basal Like Gene Expression Pattern

Else Marie Huuse1, Siver Andre Moestue1, Olav Engebråten2,3, Tone Frost Bathen1, Ingrid Susann Gribbestad1

1Department of Circulation and Medical Imaging, Norwegian University of Science and Technology (NTNU), Trondheim, Norway; 2Department of Tumor Biology, Institute for Cancer Research, Oslo, Norway; 3Oslo University Hospital , Oslo, Norway

Molecular sub-classification of breast cancer based on gene expression pattern represents clinically distinct patient groups with different outcome. Two breast cancer xenograft models reflecting two of these groups: Basal like (ER-, poor prognosis) and luminal like (ER+, better prognosis), were characterized using DCE-MRI. Our results shows a significant higher Ktrans in basal like than in luminal like small tumors, however, this difference disappears for large tumors. Estradiol withdrawal had minor effect on growth and DCE-MRI derived parameters for the basal like tumors. The luminal like tumors ceased to grow and had a significant increase in Ktrans and ve .

2790. Comparative Analysis of Gd Vs Dy in DSC-MRI Studies of a High Grade Glioma Murine Model

Rocío Pérez-Carro1, Jesús Pacheco-Torres1, Sebastián Cerdán1, Pilar Lopez-Larrubia1

1Insituto de Investigaciones Biomedicas, CSIC/UAM, Madrid, Spain

Gd(III) is the lanthanide ion more widely used as longitudinal relaxation enhancer due to its long electronic relaxation time. Stable Gd complexes are the T1 contrast agents more used for MRI studies. Other paramagnetic lanthanides as Dy(III) are also employed as contrast agents in dynamic susceptibility contrast MRI. We used both Gd and Dy containing chelates in perfusion studies to yield parametric maps (CBF, CBV and MTT) in a high grade glioma rat model. The goal is to establish an optimal method to delimit and characterize brain regions in the murine model to test the effectiveness of antiangiogenic therapies.

2791. Modulations of Intra and Extracellular PH in Tumor Variants Defective in Either Respiration or Glycolysis, Observed by in Vivo MRS

Norbert W. Lutz1, Johanna Chiche2, Yann Le Fur1, Christophe Vilmen1, Frédéric Frassineti3, Laurent Daniel3, Jacques Pouysségur2, Patrick J. Cozzone1

1CRMBM UMR 6612 CNRS, Aix-Marseille University, Medical School, Marseille, PACA, France; 2Institute of Developmental Biology and Cancer Research CNRS UMR 6543, Centre A. Lacassagne, Nice; 3Inserm UMR 911-CRO2, Aix-Marseille University, Medical School

The current use of angiogenesis inhibitors for cancer treatment requires further modifications of the hypoxic tumor microenvironment to achieve complete tumor regression. To contribute to the development of a new treatment strategy, we investigated effects of modulations of multiple mechanisms of glycolytic activity and pH regulation on intracellular and extracellular pH (pHi, pHe) by 31P NMR spectroscopy of tumor xenografts in nude mice. Three ras-transformed fibroblast variants were compared: wild-type CCL39, and mutants defective in either glycolysis or respiration. Compared to CCL39, pHi was increased in either mutant, and pHe was less heterogenous due to a reduction of low-pHe regions.

2792. Single Dose (0.1mmol/kg) Brain Magnetic Resonance Imaging with Gadobutrol at 1.5T and 3.0T: Comparison to 0.15mmol/kg Gadoterate Meglumine

Harald Kramer1, Val M. Runge2, L Gill Naul2, Alan T. Loynachan3, Maximilian F. Reiser1, Bernd J. Wintersperger1

1Department of Clinical Radiology, University Hospital Munich, Munich, Germany; 2Scott and White Memorial Hospital, TX, United States; 3University of Kentucky, KY, United States

The detection of a link between the application of Gd contrast agents highlights the need for dedicated application protocols. The purpose of the study was to evaluate the efficacy of single dose gadobutrol compared to a substantially higher dose gadoterate meglumine in a tumor model at 1.5T and 3.0T. All animals were implanted Glioma cells using an implanted plastic brain cannula. After 7 days brain MR exams were performed whether with gadobutrol or gadoterate meglumine with a 24h interval. After the second MRI brains harvested for histopathologic assessment. Data were evaluated regarding SNR, CNR and lesion enhancement (LE).

2793. Integrated MRI Approaches to Interrogate Tumor Oxygenation and Vascular Perfusion of Orthotopic Brain Tumors in a Mouse Model

Heling Zhou1, Amyn A. Habib1, Ralph P. Mason1, Dawen Zhao1

1Radiology, UT Southwestern Medical Center, Dallas, TX, United States

Glioma is a lethal cancer. It is imperative to non-invasively evaluate intracranial tumor microenvironment. We applied multiple MRI approaches to evaluate tumor microenvironment in orthotopic gliomas in a mouse model. An interleaved T2*-weighted and T1-weighted sequence, sensitive to both blood and tissue oxygen tension, was applied to assess tumor oxygenation. Our results showed significantly increased signal intensity in intracranial tumors with oxygen inhalation. Dynamic susceptibility contrast MRI was used to evaluate vascular perfusion and correlate with change in oxygenation. Our study suggests the integrated MRI approaches will be useful to evaluate interplay of tumor oxygenation and hemodynamics.

Breast Cancer: Spectroscopy & More

Hall B Tuesday 13:30-15:30

2794. Intrinsic Susceptibility Contrast (R2*) in the Evaluation of Tumour Oxygenation at Baseline and in Response to Neoadjuvant Chemotherapy in Breast Cancer

Sonia P. Li1, N J. Taylor2, J J. Stirling2, Mei-Lin W. Ah-See1, Mark J. Beresford1, David J. Collins3, James A. d'Arcy3, Andreas Makris1, Anwar R. Padhani2

1Mount Vernon Hospital, Northwood, Middlesex HA6 2RN, United Kingdom; 2Paul Strickland Scanner Centre, Mount Vernon Hospital, Northwood, Middlesex HA6 2RN, United Kingdom; 3CR-UK Clinical MR Research Group, Royal Marsden Hospital, Sutton, Surrey, SM2 5PT, United Kingdom

R2* has potential to provide information about tumour oxygenation but is underexplored in breast cancer. Here, primary carcinomas were imaged with multiparametric MRI before and after 2 cycles of neoadjuvant chemotherapy. Correlations between R2* and kinetic parameters were investigated. R2* as a predictor of pathological benefit was compared with DCE/DSC-MRI parameters. Significant inverse correlations between R2* and blood flow/volume in untreated cancers confirm that R2* reflects blood oxygenation; however this relationship disappears after treatment. Increases in R2* in responders suggest that cancers become more hypoxic with successful treatment. R2* was a relatively poor response predictor compared with some DCE and DSC-MRI parameters.

2795. Phospholipid Contents Measured in Human Breast Cancer and in Healthy Glandular Breast Tissue in Vivo at 7T

Dennis WJ Klomp1, Bart van de Bank1, Alexander Raaijmakers2, Mies Korteweg1, Cecilia Possanzini3, Vincent Boer1, Nico van de Berg2, Maurice van de Bosch1, Peter Luijten1

1Radiology, University Medical Center Utrecht, Utrecht, Netherlands; 2Radiotherapy, University Medical Center Utrecht, Utrecht, Netherlands; 3Philips Health Care

In this work we demonstrate the ability to detect multiple phospholipid metabolites in vivo in the human female breast using focused field coils at 7T. For the first time ever, these signals are detected locally with a spatial resolution of 10 ml. The signals are detected from breast cancer tissue, which has a high concentration of choline levels and even from healthy, glandular breast tissue as well, which has low levels of total choline (i.e. < 0.5 mM).

2796. A Total Choline Quantification Method for Water- And Lipid-Suppressed Breast Spectra at 3T

Chenguang Zhao1, Patrick Bolan2, Melanie Royce3, Anne Marie Wallace4, Laurel Sillerud5, Steven Eberhardt6, Robert Rosenberg6, Lesley Lomo7, Stefan Posse

1Department of Neurology, University of New Mexico, Albuquerque, NM, United States; 2Center of Magnetic Resonance Research, University of Minnesota; 3Cancer Research & Treatment Center, Univeristy of New Mexico; 4Department of Surgery, University of New Mexico; 5Biochemistry and Molecular Biology, University of New Mexico; 6Department of Radiology, University of New Mexico; 7Pathology, University of New Mexico

Quantification of total Choline compounds in breast spectra is challenging due to the contamination of unsuppressed lipids. In vivo breast spectra in healthy controls were acquired using proton echo planar spectroscopic imaging. Localized spectra were fitted across the 4.0-2.0ppm range by LCModel using a basis-set with singlet resonances for tCho and lipid peaks. LCModel fitting enables identification of the tCho baseline and quantification of the peak area by spectral integration. In vivo tCho concentrations were consistent with literature values. This method is suitable for automatic tCho quantification of breast spectroscopic imaging data of low quality.

2797. Digital Breast Phantom for Evaluating Dynamic Accelerated Imaging Methods

Leah Christine Henze1, Catherine J. Moran2, Matthew R. Smith2, Frederick Kelcz3, Alexey Samsonov3, Sean B. Fain2, Walter F. Block, 12

1Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States; 2Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, United States; 3Department of Radiology, University of Wisconsin-Madison, Madison, WI, United States

Improving temporal resolution without compromising spatial resolution has the potential to improve differential diagnosis in breast cancer. Several accelerated imaging methods exist that may aid in this endeavor but it is difficult to quantitatively measure and compare their respective performance. To address this problem, we have created a digital breast phantom comprised of enhancing lesions surrounded by normal background breast tissue. This phantom provides realistic, simulated k-space data for both Cartesian and non Cartesian acceleration methods. We describe the creation of this phantom and demonstrate its use.

2798. Time-To-Peak and Spherical Shape Index from Dynamic Contrast Enhanced MRI as Combined Predictors of Tumor Malignancy

Fang Liu1,2, Anat Kornecki3, Olga Shmuilovich3, Neil Gelman1,2

1Lawson Imaging, Lawson Health Research Institute, London, Ontario, Canada; 2Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada; 3Department of Diagnostic Imaging, St. Joseph's Health Center, London, Ontario, Canada

Most previous quantitative studies using dynamic contrast enhanced MRI of the breast have analyzed either signal time evolution features or morphological features as predictors of malignancy. However, combined use of both types of features should provide stronger predictors. In this study, a time evolution feature (time to peak (TTP)) and a 3D morphological feature (spherical shape index (SSI)), both obtained from tumor regions segmented automatically with K-means clustering, were investigated as independent and combined predictors of malignancy. Results suggest that the combination provides stronger discrimination of malignant versus benign lesions than either feature alone.

2799. Improving Suspicious Breast Lesion Characterization Using Lesion Fractional Volume Washout Kinetic Analysis

Jie Huang1, Lori Hoisington1, Sarah Schafer1, Xiaopeng Zong1, Kevin Berger1

1Department of Radiology, Michigan State University, East Lansing, MI, United States

This study investigated using lesion fractional volume washout (WO) kinetic analysis for improving the characterization of suspicious contrast-enhancing breast lesions. The WO volume fraction was found to be significantly different between the biopsy-proven benign and malignant lesions of all the suspicious breast lesions with BI-RADS assessment of 4 or 5. It showed a potential to improve the positive predictive value of the biopsies by an improvement rate of 86.8%, and consequently would yield a 72.2% reduction rate to the total number of unnecessary biopsies.

2800. Qualitative and Quantitative Assessment of Breast Tumour Appearance in Diffusion-Weighted Imaging and Correlation with Molecular Prognostic Factors

Giuseppe Petralia1, Luke Bonello1, Paul Summers1, Sara Raimondi2, Ala Malasevschi1, Roberto Di Filippi1, Dow-Mu Koh3, Marzia Locatelli4, Giuseppe Curigliano4, Massimo Bellomi1

1Radiology, Istituto Europeo di Oncologia, Milan, Lombardia, Italy; 2Epidemiology and Biostatistics, Istituto Europeo di Oncologia, Milan, Lombardia, Italy; 3Radiology, Royal Marsden Hospital, Sutton, United Kingdom; 4Medical Oncology, Istituto Europeo di Oncologia, Milan, Lombardia, Italy

We performed a qualitative analysis of diffusion weighted magnetic resonance imaging (DW-MRI) of breast tumours to identify common semiotic characteristics, and a quantitative analysis in 28 patients to examine the correlation of DW-MRI with molecular prognostic factors, and to assess the interobserver variability in the calculation of ADC values. Hyper-intensity in DW images and low ADC values (mean 1.1 x 10-3mm2/sec) were common characteristics in the breast tumours studied. Interobserver variability was 20%.A marginally significant correlation between ADC value and percentage of PgR and possible higher mean ADC values for the LUMINAL A subtype warrant further study.

Prostate Cancer - Clinical

Hall B Wednesday 13:30-15:30

2801. DCE-MRI at 3T in Patients with Advanced Prostate Cancer Undergoing Androgen Deprivation Therapy

Tristan Barrett1, Andrew Gill1,2, Masako Kataoka1, Vincent J. Gnanapragasam3, Andrew Priest1,2, Ilse Joubert1, Mary McLean2,4, Martin J. Graves1, David J. Lomas1, John R. Griffiths2, David Neal3,5, Evis Sala1

1Radiology, Addenbrooke's Hospital, Cambridge, United Kingdom; 2Medical Physics, Addenbrooke's Hospital, Cambridge, United Kingdom; 3Urology, Addenbrooke's Hospital, Cambridge, United Kingdom; 4 Cambridge Research Institute, Cancer Research UK,, Cambridge, United Kingdom; 5Cambridge Research Institute, Cancer Research UK, Cambridge, United Kingdom

Prostate cancer is the commonest malignancy in UK men. Androgen deprivation therapy (ADT) remains an important treatment. However, 51% eventually develop resistance, making it necessary to identify quantitative markers that demonstrate ADT response. We used dynamic-contrast-enhancement (DCE)-MRI to measure permeability parameters before and 3 months after ADT in 12 patients with biopsy-proven prostate cancer. There was a significant reduction in all parameters measured (Ktrans, kep, Ve, IAUGC-90), whereas ‘normal’ tissue showed no significant change. These results suggest that DCE-MRI has potential to monitor ADT response and select to patients with AD resistance at early time-points, allowing consideration of other treatments.

2802. Can Ex-Vivo MRI Be Used for Correlating Diffusion Weighted Imaging Parameters to Pathology for Validation of In-Vivo Multiparametric MRI

Michael A. Jacobs1,2, Vadappuram Chacko1, Baasil Okollie1, Tamara Lotan3, Katarzyna J. Macura1

1The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, United States; 2Sidney Kimmel Comprehensive Cancer Center, The Johns Hopkins University School of Medicine; 3Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States

By using a multiparametric approach to investigate the in-vivo and ex-viso characteristics of prostate cancer a better understanding of prostate cancer aggressiveness and tumor staging can be realized. This radiological-pathological correlation will assist in detection, localization, assessment of the tumor microenvironment. Such a comprehensive approach offers more power to evaluate prostate disease than any single measure alone.

2803. The Effect of Spatial Resolution on the Correspondence Between Hematoxylin-Eosin Stained Sections and MR Images for Prostate Cancer

Greetje Groenendaal1, Maaike R. Moman1, Johannes G. Korporaal1, Paul J. van Diest2, Marco van Vulpen1, Marielle E.P. Philippens1, Uulke A. van der Heide1

1Radiotherapy, University Medical Center Utrecht, Utrecht, Netherlands; 2Pathology, University Medical Center Utrecht, Utrecht, Netherlands

Sensitivity and specificity values of DW-MRI and DCE-MRI for prostate cancer are often based on the correspondence of imaging and pathology within relatively large volumes inside the prostate. However, for prognosis, therapy selection and focal therapy, decisions on a voxel level are required. We investigated at which spatial resolution validation of MR images with hematoxylin-eosin stained sections is meaningful. We found that the chance is small that matching tumor voxels are found on the MR images and pathology within a volume smaller than 0.4 cc. This puts limitations on the accuracy at which tumor volume and extent can be determined.

2804. Echo Planar Spectroscopic Imaging with Peak-Enhanced 2D-Capon Analysis for Prostate Studies

Fred J. Frigo1, Andreas Ebel1

1GE Healthcare, Waukesha, WI, United States

Two-dimensional echo planar spectroscopic imaging (EPSI) may be used for clinical evaluation of the human prostate. The results of EPSI studies are typically represented as the set of MRS absorption spectra in which the concentration of each metabolite can be determined on the basis of its frequency representation in the voxel of interest. In addition to frequency information, the damping characteristics of each metabolite can also be determined by using two-dimensional Capon analysis. This damping information may be used in conjunction with the frequency information to more easily identify metabolites during clinical diagnosis of EPSI prostate studies.

2805. 31P MR Spectroscopy for Prostate Cancer Characterization at 7Tesla

Catalina Arteaga1, Uulke A. van der Heide1, Marco van Vulpen1, Peter R. Luijten2, Dennis W.J. Klomp2

1Radiotherapy, UMC Utrecht, Utrecht, Netherlands; 2Radiology, UMC Utrecht, Utrecht, Netherlands

We showed the feasibility of obtaining 31P MRS in the prostate area at 7T with the use of anatomy imaging and optimized B0 shimming. Individual detection of PC, GPC, GPE and GPC was feasible, illustrating the benefit of going to higher spectral resolutions that can be obtained at higher fields like 7T.

2806. Signal Characterization of a Novel Two-Channel Rigid Endorectal Coil for MR Imaging of the Prostate

Niranjan Venugopal1,2, Axel Krieger3, Herve Momo Jeufnack4, Ken Bradshaw4, Boyd McCurdy5, Lawrence Ryner6

1Physics and Astronomy, University of Manitoba, Winnipeg, MB, Canada; 2Medical Physics, CancerCare Manitoba, Winnipeg, MB, Canada; 3Sentinelle Medical, Toronto, Ontario, Canada; 4Sentinelle Medical Inc.; 5Medical Physic, CancerCare Manitoba, Winnipeg, MB, Canada; 6National Research Council Institute for Biodiagnostics, Winnipeg, MB, Canada

We present a comparison of a newly designed dual-channel, rigid endorectal coil for both imaging and spectroscopic imaging of the prostate with a standard, single-channel, inflatable endorectal coil, demonstrating a SNR improvement of up to ~500% in the near-coil area (where the prostate peripheral zone is located), and up to ~150% at depth (where the prostate central zone is located). This huge SNR improvement allows for greatly improved MR/MRSI imaging of the prostate.

2807. Short Echo Time in Vivo Prostate MRSI

Niranjan Venugopal1, Boyd McCurdy2, Darrel Drachenberg3, Salem Al Mehari3, Aziz Alamri3, Gurudarshan Sandhu3, Sri Sivalingam3, Lawrence Ryner4

1Physics and Astronomy, University of Manitoba, Winnipeg, MB, Canada; 2Medical Physics, CancerCare Manitoba, Winnipeg, MB, Canada; 3Urology, University of Manitoba, Winnipeg, MB, Canada; 4National Research Council Institute for Biodiagnostics, Winnipeg, MB, Canada

We present a robust method improve the quality of in vivo prostate MRSI data acquisition by utilizing an optimized conformal voxel technique coupled with a spatial-spectral excitation PRESS pulse sequence for short echo time acquisitions.The PRESS pulse sequence was modified to include the optimized conformal voxel MR spectroscopic imaging technique (CV-MRS). In vivo implementation of this optimized MRSI technique confirms the reduction in peripheral lipid contamination, and improved the quality of spectra throughout the prostate. In summary we have demonstrated the utility of short TE in vivo prostate MRSI acquisitions, which provides significant signal increase and reveal short TE metabolites to potentially improve prostate cancer detection.

2808. Clinical Prostate T1 Quantification Using a Magnetization-Prepared Spiral Technique

Warren Foltz1, Masoom Haider2,3, Peter Chung1, Andrew Bayley1, Charles Catton1, Venkat Ramanan4, David Jaffray1, Graham Wright4, Cynthia Ménard1

1Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ontario, Canada; 2Medical Imaging, University Health Network, Toronto, Ontario, Canada; 3Medical Imaging, University of Toronto; 4Sunnybrook Research Institute, Toronto, Ontario, Canada

A magnetization-prepared spiral imaging strategy with RF cycling has been adapted for time-efficient multi-slice clinical prostate T1 quantification at 1.5T. In vitro testing validated an overall robustness to RF offsets. Pilot studies in patients without prior external beam radiation demonstrated an equivalence between zonal T1, with reduced T1 in peripheral zone tumors. Intra-patient zonal T1 variabilities motivate individial measurements for dynamic studies of vascular metrics. SNR analysis identified useful region volumes for thermal-noise insensitive measurements, to guide protocol design for future voxel-based prostate T1 mapping. High RF insensitivity combined with time-efficiency suggests method potential for robust implementation on stronger magnets.

2809. Multi-Slice Parametric Mapping in Prostate DCE-MRI

Ryan Alexander Priest1, Xin Li2, Ian J. Tagge2, William J. Woodward2, Tomasz M. Beer3,4, Charles S. Springer, Jr. 2,4, Mark G. Garzotto5,6

1Diagnostic Radiology, Oregon Health & Science University, Portland, OR, United States; 2Advanced Imaging Research Center, Oregon Health & Science University, Portland, OR, United States; 3Hematology/Oncology, Oregon Health & Science University, Portland, OR, United States; 4Knight Cancer Institute, Oregon Health & Science University, Portland, OR, United States; 5Urology, Oregon Health & Science University, Portland, OR, United States; 6Portland VA Medical Center, Portland, OR, United States

Pharmacokinetic analysis of data generated using Dynamic-Contrast-Enhanced MRI (DCE-MRI) has proven to be a valuable tool in the evaluation of the vascular pathophysiology of prostate adenocarcinoma. With improved hardware, multi-slice parametric mapping has become feasible and could provide valuable insight to complement conventional T2*-weighted images. In this study multi-slice parametric mapping was performed with DCE-MRI data using both the standard model (SM) and the first generation shutter-speed model (SSM1). Parametric maps were then compared with biopsy results.

2810. Ability of Combined DTI and DCE MRI to Predict Pathologic Gleason Score

Piotr Kozlowski1,2, Silvia D. Chang2, Edward C. Jones3, Ran Meng1, Nicholas Buchan4, S Larry Goldenberg, 4,5

1UBC MRI Research Centre, Vancouver, BC, Canada; 2Radiology, Univeristy of British Columbia, Vancouver, BC, Canada; 3Pathology and Laboratory Medicine, Univeristy of British Columbia, Vancouver, BC, Canada; 4Vancouver Prostate Centre, Vancouver, BC, Canada; 5Urologic Sciences, Univeristy of British Columbia, Vancouver, BC, Canada

DTI and DCE MRI were carried out in 27 prostate cancer patients. Mean diffusivity, fractional anisotropy and pharmacokinetic modeling parameters calculated from MRI data were correlated with Gleason score determined by biopsy and prostatectomy specimens. Mean diffusivity and fractional anisotropy correlated significantly with Gleason score, as demonstrated by the Spearman’s rank correlation test and the ordinal logistic regression modelling. These results strongly suggest that DTI MRI is capable of non-invasively grading prostate tumours.

2811. Investigation of Prostate Cancer Using Diffusion Weighted IVIM Imaging

Jörg Döpfert1, Andreas Lemke1, Anja Weidner2, Lothar Rudi Schad1

1Department of Computer Assisted Clinical Medicine, Heidelberg University, Mannheim, Germany; 2Institute of Radiology and Nuclear Medicine, Heidelberg University, Mannheim, Germany

In this work, the decrease of the apparent diffusion coefficient (ADC) in cancerous prostate tissue compared to healthy prostate tissue is investigated using the Intravoxel Incoherent Motion (IVIM) Theory. Moreover , the extracted parameters and the calculated parameter maps are analyzed with regard to the differentiation between cancerous and healthy tissue. Therefore, diffusion weighted images of the prostate of 9 patients with prostate carcinoma were acquired and evaluated, yielding a significant decrease of the ADC and the perfusion fraction in cancerous tissue compared to healthy tissue. The results suggest that the decrease of the ADC primarily comes from perfusion effects.

2812. Comparison of HASTE & EPI Diffusion Weighted Images in the Prostate

Ben Babourina-Brooks1, Gary Cowin1, Deming Wang1

1Centre for Magnetic Resonance, University of Queensland, Brisbane, Queensland, Australia

A comparison of two diffusion weighted imaging sequences, Echo Planar Imaging (EPI) and Half fourier Aquisition Single shot Turbo spin echo (HASTE), was conducted in the prostate. EPI, which is currently the main DWI method, is highly susceptible to artifacts, namely magnetic susceptibility and chemical shift. We propose to use a HASTE sequence, which is less affected by these artifacts, to gain more reproducible Apparent Diffusion Coefficient (ADC) values and increase ADC map quality. Advancements in this area will lead to more accurate prostate cancer localisation.

2813. 3T MR Spectroscopic Imaging with and Without Endorectal Coil in Localizing Prostate Cancer: An Initial Experience

Derya Yakar1, Stijn Heijmink, Jelle Barentsz, Christina Hulsbergen - Van de Kaa, Jurgen Fütterer, Tom Scheenen

1Radboud University Nijmegen Medical Centre, Nijmegen, Gelderland, Netherlands

Currently used techniques in localizing prostate cancer (Pca) have definite shortcomings. We studied the potential of 3D- magnetic resonance spectroscopic imaging (MRSI) with and without an endorectal coil (ERC) at 3T in improving the localization of Pca. Eighteen patients with histologically proven Pca underwent an MRSI examination with and without the use of an ERC. The areas under the receiver operating characteristic curve were improved for all of the readers with the use of an ERC. For one reader this improvement was statistically significant (p< .05). Overall the AUC for all readers was quite low, with and without the use of an ERC. Emphasis have to be made on the fact that these results concern an initial experience based on a first cohort of patients examined at 3T with 3D-MRSI in our institution. In our experience more recent data of patients examined with 3D-MRSI at 3T in our institution are far more promising due to higher signal-to-noise ratios resulting in better fitted spectra and less non ratable ROIs.

2814. Clinical Prostate T2 Quantification Using a Magnetization-Prepared Spiral Technique

Warren Foltz1, Supriya Chopra1, Peter Chung1, Andrew Bayley1, Charles Catton1, David Jaffray1, Graham Wright2, Masoom Haider3,4, Cynthia Ménard1

1Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ontario, Canada; 2Sunnybrook Research Institute, Toronto, Ontario, Canada; 3Medical Imaging, University Health Network, Toronto, Ontario, Canada; 4Medical Imaging, University of Toronto

A magnetization-prepared spiral imaging technique, termed T2prep, was adapted for robust time-efficient clinical prostate evaluation, and piloted in two prostate cancer cohorts. The patient groups presented with: (A) no prior history of external beam radiation; and (B) biochemical failure after radiotherapy. Cohorts were scanned (A) without and (B) with an endo-rectal coil in tandem with a torso phased-array, respectively. Prostate zonal and tumor T2 values supported known trends. For each cohort, an SNR analysis was performed to identify minimum region volumes for thermal-noise insensitive measurements, and to guide protocol design for future voxel-based anlaysis.

2815. Early Quantititative T1 and T2 Response of the Prostate Gland During Radiotherapy

Warren Foltz1, Andy Wu1, Anna Kirilova1, Peter Chung1, Andrew Bayley1, Charles Catton1, David Jaffray1, Masoom Haider2, Cynthia Ménard1

1Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ontario, Canada; 2Medical Imaging, University Health Network, Toronto, Ontario, Canada

Magnetization-prepared spiral imaging techniques were adapted for quantitative T2 and T1 characterization of early radiation response in patients with low/intermediate risk of localized cancer throughout 8-weeks of radiotherapy. Early central gland T2 elevation preceded persistent tumor T2 elevation, and late reduction in peripheral zone T2; observations which support a known loss of contrast in diagnostic images, and a complementary role for T2 in ADC and DCE radiation response evaluation. Zonal and tumor T1 measures were insensitive to radiotherapy. However, considerable inter-patient but minor intra-patient T1 heterogeneities support a sufficiency of baseline T1 scanning for serial quantitative perfusion analysis during radiotherapy.

Cancer (Miscellaneous)

Hall B Thursday 13:30-15:30

2816. MRI-Based ‘Wait-And-See’ Policy in Clinical Complete Responders to Chemoradiation in Rectal Cancer: A Promising Alternative

Monique Maas1, Doenja Lambregts1, Ronald van Dam2, Patty Nelemans3, Guido Lammering4, Rob Jansen5, Regina Beets-Tan1, Geerard Beets2

1Radiology, Maastricht University Medical Center, Maastricht, Limburg, Netherlands; 2Surgery, Maastricht University Medical Center, Maastricht, Limburg, Netherlands; 3Epidemiology, Maastricht University Medical Center, Maastricht, Limburg, Netherlands; 4Radiotherapy, Maastricht University Medical Center, Maastricht, Limburg, Netherlands; 5Medical Oncology, Maastricht University Medical Center, Maastricht, Limburg, Netherlands

When - after neoadjuvant chemoradiation for rectal cancer - imaging could accurately select the complete responders, surgery might safely be omitted and patients can undergo a wait-and-see policy. This study aims to evaluate whether MRI at 1.5T is accurate enough to select patients for wait-and-see and can safely be used as a follow-up tool.

2817. N-Stage Assessment in Non-Small Cell Lung Cancer Patients: Comparison of Capability Among STIR Turbo SE Imaging, Diffusion-Weighted Imaging and FDG-PET/CT

Daisuke Takenaka1, Yoshiharu Ohno1, Keiko Matsumoto1, Hisanobu Koyama1, Yumiko Onishi1, Munenobu Nogami1, Nobukazu Aoyama2, Hideaki Kawamitsu2, Kazuro Sugimura1

1Radiology, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan; 2Division of Radiology, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan

FDG-PET/CT can assess morphological and metabolic information at same time, and widely utilized for N-stage assessment in non-small cell lung cancer (NSCLC) patients. In the last decade, short inversion time inversion recovery (STIR) turbo spin-echo (SE) imaging has been determined at least as valuable as PET/CT in this setting. Recently, diffusion-weighted image (DWI) is suggested as new technique for differentiation of metastatic lymph nodes from non-metastatic lymph nodes. The purpose of this study was to prospectively and directly compare capability of N-stage assessment among integrated FDG-PET/CT, STIR turbo SE imaging and DWI in NSCLC patients.

2818. Assessment of the Early Response to Chemotherapy with Diffusion-Weighted MRI in Advanced Lung Cancer Patients-Comparison with FDG-PET-

Tatsuro Tsuchida1, Miwa Morikawa2, Yukihiro Umeda2, Masato Sasaki3, Tomohito Kamibayashi1, Hirohiko Kimura1

1Dept. of Radiology, University of Fukui, Fukui, Japan; 2Dept. of Respiratory Medicine, University of Fukui, Fukui, Japan; 3Dept. of Thoracic Surgery, University of Fukui, Fukui, Japan

The purpose of this study was to examine the utility of DWI-MRI for the assessment of early response to chemotherapy in patients with advanced lung cancer by comparing FDG-PET. Twenty-two lung cancer patients received MRI, FDG-PET, and CT examination before and after 1 cycle of chemotherapy. Progression-free survival (PSF) between responder and non-responder against chemotherapy was compared by means of % change of ADC and SUV. Both index indicated that responder demonstrated significant longer PSF and DWI-MRI will be a promising tool for the assessment of the early response to chemotherapy.

2819. Perfusion MRI of Solitary Pulmonary Nodules at 3T: Assessment of Perfusion Parameters and Correlation with Histology

Hatsuho Mamata1, Junichi Tokuda1, Ritu Gill1, Robert F. Padera2, Robert E. Lenkinski3, David J. Sugarbaker4, Hiroto Hatabu1

1Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States; 2Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States; 3Radiology, Beth Israel Decones Medical Center, Harvard Medical School, Boston, MA, United States; 4Thoracic surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States

Solitary pulmonary nodule (SPN) is one of the most common findings in chest imaging. It is important to avoid unnecessary intervention for benign lesions, thereby lowering the associated mortality / morbidity. In this study, we applied perfusion MRI to evaluate perfusion characteristics of SPN and feasibility of perfusion MRI as a diagnostic tool to differentiate malignant from benign SPN. Perfusion MRI parameters and TI curve has great potential to differentiate malignant vs. benign SPN, thus to avoid unnecessary surgical interventions.

2820. Feasibility of Detecting Radiation-Induced Lung Injury in Non-Small Cell Lung Cancer Patients Using Hyperpolarized Helium-3 MRI

Rob H. Ireland1,2, Omar S. Din2, James A. Swinscoe2, Edwin JR van Beek3, Matthew QF Hatton2, Jim M. Wild1

1Academic Unit of Radiology, University of Sheffield, Sheffield, United Kingdom; 2Academic Unit of Clinical Oncology, University of Sheffield, Sheffield, United Kingdom; 3Department of Radiology, University of Iowa, Iowa, IA, United States

This preliminary work demonstrates the feasibility of pre-treatment assessment of lung ventilation and post-treatment detection of radiation-induced lung damage using 3He-MRI for NSCLC patients.

2821. Intracellular Acidification of Human Melanoma Xenografts by the Respiratory Inhibitor Lonidamine Plus Hyperglycemia: A 31P Magnetic Resonance Spectroscopy Study

Kavindra Nath1, Elliot C. Woods1, Seung Cheol Lee1, David S. Nelson1, Dennis B. Leeper2, Rong Zhou1, Lin Li1, Jerry D. Glickson1

1Radiology (Molecular Imaging Section), University of Pennsylvania, Philadelphia, PA, United States; 2Radiation Oncology, Thomas Jefferson University, Philadelphia, PA, United States

In vivo 31P magnetic resonance spectroscopy illustrates that human melanoma xenografts can be acidified by induction of hyperglycemia combined with administration of lonidamine, an inhibitor of mitochondrial respiration. In melanoma xenograft (10-13 mm diameter), intracellular pH (pHi, measured by chemical shift of the Pi resonance) was reduced by ~0.7 unit during i.v. infusion of glucose (0.6 M) for 120 min along with administration of lonidamine (50 mg/kg). Preliminary result of this study shows that lonidamine combined with hyperglycemia acidified human melanoma xenografts by reducing pHi, a more critical parameter for thermosensitization to improve tumor response to alkylating agents.

2822. Monitoring Bone Marrow Changes During Chemoradiotherapy Using MRI Fat Quantification

Mark Bydder1, Yun Liang2, Huanzhou Yu3, Ann Shimakawa3, Jean Brittain3, Graeme Bydder1, Loren Mell2

1Radiology, University of California San Diego, San Diego, CA, United States; 2Radiation Oncology, University of California San Diego, San Diego, CA, United States; 3GE Healthcare, Applied Science Lab, United States

The goal of this study was to evaluate a non-invasive magnetic resonance imaging method of fat quantification as a measure of yellow bone marrow in the pelvis and spine. This is a new technology that will enable monitoring of response to therapy and assessment of the effectiveness of strategies to reduce hematology toxicity.

2823. Motion-Sensitized Driven-Equilibrium (MSDE) Turbo Spin-Echo Sequence Increases Radiologists' Diagnostic Performance in Detection of Brain Metastasis

Eiki Nagao1, Takashi Yoshiura1, Akio Hiwatashi1, Koji Yamashita1, Hironori Kamano1, Yukihisa Takayama1, Tuvshinjargal Dashjamts1, Makoto Obara2, Tomoyuki Okuaki2, Hiroshi Honda1

1Clinical radiology of Kyushu-university, Fukuoka, Japan; 2Philips Electoronics Japan

Motion-sensitized driven-equilibrium (MSDE) sequence has been reported to effectively suppress signals from flowing blood in vessels that can mimic the brain metastases on post-contrast T1-weighted images. We performed an observer test to determine whether use of a 3D turbo spin-echo (TSE) sequence with MSDE increases radiologists?f diagnostic performances in detecting brain metastases comparing to a conventional 3D gradient-echo sequence (MPRAGE). A jackknife free-response receiver operating characteristic (JAFROC) analysis showed that TSE with MSDE increases radiologists?f diagnostic performances compared to MPRAGE. The reading time was also significantly shortened by use of MSDE.

2824. Correlation of a Priori DCE-MRI Data with Ki-67 and HIF-1α Expression Levels in Neck Nodal Metastases: Initial Analysis

Jacobus FA Jansen1, Diane Carlson1, Bhuvanesh Singh1, Hilda Stambuk1, Ya Wang1, Dennis Kraus1, Richard Wong1, Snehal Patel1, Jatin Shah1, Jason Koutcher1, Amita Shukla-Dave1

1MSKCC, NY, United States

Pretreatment DCE-MRI was performed on neck nodal metastases of 12 patients who underwent surgery. Surgical specimens were analyzed with immunohistochemistry (IHC) assays for Ki-67 (reflecting cellular proliferation) and HIF-1α (hypoxia inducible transcription factor). Spearman correlation was used to correlate DCE-MRI and molecular marker data. Significant correlation results were observed between DCE-MRI data (Ktrans and ve) and tumor hypoxia, and proliferation as measured by Ki67 and HIF-1á expression levels, respectively. Future studies with larger patient populations need to be carried out to confirm pretreatment DCE-MRI findings and molecular marker results in biopsy samples for better patient management.

2825. Focused Primary Tumour Staging and WB-MRI Distant Disease Assessment: A Potential All-In-One Staging Tool

Martin D. Pickles1, Lindsay W. Turnbull1

1Centre for MR Investigations, University of Hull, Hull, East Yorkshire, United Kingdom

Oncology patients undergo multiple imaging investigations to stage their disease. The aim of this study was to investigate the feasibility of a focused primary tumour (breast or prostate) examination in combination with a WB-MRI for staging of distant disease. If successful we propose the addition of this technique could allow the omission of other examinations, such as radionuclide imaging, thereby streamlining the current imaging pathway. We conclude that focused primary tumour examinations in combination with a WB-MRI for staging of distant disease is feasible. However, the technique needs to validated in a much larger cohort than the one studied.

2826. Imaging Characteristics of Metastasis in Whole Body Diffusion Weighted Imaging of Renal Clear Cell Carcinoma

Jing Liu1, XiaoYing Wang1, XueXiang Jiang1

1Department of Radiology, Peking University First Hospital, BeiJing, China

The study aimed to explore the role of Whole-body DWI in clear cell renal cell carcinoma (RCC) and obtain the imaging characteristics of metastases. Ten patients with histologically confimed clear cell RCC and possible metastatic lesions were underwent standard Whole-body DWI, chest CT and routine MR examinations before chemotherapy. The results showed that the whole body DWI was very sensitive to the metastatic lesions in clear cell RCC and DWI showed its high rate of detection in pulmonary metastases. Whole body DWI had revealed great potential in metastatic screening of clear cell RCC.

2827. Whole Body Imaging Multiparametric (T2/DWI/DCE) and Advanced Multimodality (PET/CT) for Detection of Recurrent Metastatic Cancer

Michael A. Jacobs1, Li Pan2, Katarzyna J. Macura1, Thorsten Feiweier3, Wilhelm Horger3, Christine Lorenz2, Richard L. Wahl1

1The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, United States; 2Center for Applied Medical Imaging, Siemens Corporation, Corporate Research, Baltimore,, MD, United States; 3Siemens AG, Healthcare Sector, Magnetic Resonance, Germany

By using Whole Body MR and PET/CT approach to investigate metastatic disease can lead a better understanding of cancer aggressiveness. Functional imaging such as DWI/ADC, DCE-MR and 11C Choline PET is feasible and thus, combined DWI/ADC mapping, and PET/CT provides radiological biomarkers of molecular environment and could provide targets imaging treatment response.

B1 +/- Mapping

Hall B Monday 14:00-16:00

2828. B1 Mapping of an 8-Channel TX-Array Over a Human-Head-Like Volume in Less Than 2 Minutes: The XEP Sequence

Alexis Amadon1, Nicolas Boulant1, Martijn Anton Cloos1, Eric Giacomini1, Christopher John Wiggins1, Michel Luong2, Guillaume Ferrand2, Hans-Peter Fautz3

1Neurospin, CEA/DSV/I2BM, Gif-sur-Yvette, France; 2IRFU, CEA/DSM, Gif-sur-Yvette, France; 3Siemens Healthcare, Erlangen, Germany

Efficient mitigation of the RF inhomogeneity using transmit coil arrays relies on the knowledge of the individual B1-maps. As the number of transmit channels increases, so does the acquisition time of all maps. Here we focus on a fast 2D sequence proposed by Fautz et al. which we adapt for multi-slice B1-mapping. We compare its results with that of the 3D AFI sequence on a spherical phantom surrounded by 8 transmit elements at 7T. We show comparable performance with a 12-fold increase in speed, making accurate B1-mapping of the human head feasible in 1.5 minutes for 8 transmit channels.

2829. B1 Mapping with Whole Brain Coverage in Less Than One Minute

Steffen Volz1, Ulrike Nöth1, Ralf Deichmann1

1Brain Imaging Center (BIC), Goethe University Frankfurt, Frankfurt am Main, Germany

There is great demand for fast B1 mapping techniques, e.g. for correction of quantitative T1 maps. However, most methods suffer from long experiment durations. The technique presented here is based on magnetization prepared FLASH imaging with specially designed preparation and excitation pulses to allow for multislice imaging, speeding up the acquisition. Systematic errors due to relaxation effects are avoided by intensity correction of individual k-space lines. The method allows for fast B1 mapping with whole brain coverage, an in-plane resolution of 4 mm, a slice thickness of 3 mm, and an accuracy of 2% within 46 s.

2830. Fast RF Flip Angle Calibration by Bloch-Siegert Shift

Laura Sacolick1, Ling Sun2, Mika W. Vogel1, Ileana Hancu3

1GE Global Research, Garching b. Munchen, Germany; 2GE Healthcare, Waukesha, WI, United States; 3GE Global Research, Niskayuna, NY, United States

Here we present a novel method for automated RF flip angle calibration based on the Bloch-Siegert shift. The Bloch-Siegert shift is an effect where spin resonance frequency shifts when an off-resonance RF field is applied. Two off-resonance RF pulses were added to a slice-selective spin echo sequence. The off-resonance pulses induce a phase shift in the acquired signal that is proportional to B12. The signal is spatially localized in two dimensions- by slice selection and readout filter, and the signal weighted average B1 over the slice is calculated. This calibration from a starting system transmit gain to measured average flip angle is used to calculate the transmit gain setting needed to produce the desired flip angle. This is shown here at 3 Tesla in the brain, shoulder, abdomen, breast, and wrist with a total scan time for a robust implementation of 1.6 seconds.

2831. Fast and Robust B1 Mapping at 7T by the Bloch-Siegert Method

Mohammad Mehdi Khalighi1, Laura I. Sacolick2, W Thomas Dixon3, Ron D. Watkins4, Sonal Josan4, Brian K. Rutt4

1Applied Science Lab, GE Healthcare, Menlo Park, CA, United States; 2Imaging Technologies Lab, General Electric Global Research, Garching b. Munchen, Germany; 3General Electric Global Research, Niskayuna, NY, United States; 4Department of Radiology, Stanford University, Stanford, CA, United States

B1+ mapping is a critical step in the design of RF pulses for parallel transmit systems. We used the Bloch-Siegert (BS) B1+ mapping method and a 2-channel parallel transmit enabled 7T scanner to produce fast, robust and accurate B1+ maps through the human brain. Both B1+ magnitude and phase are obtained from a single sequence, employing +/-4kHz off-resonance BS pulses. B1+ magnitude and phase maps acquired with a 26s BS scan are compared with those acquired with a 640s classical double angle scan, showing that the BS method is a very good candidate for efficient B1+ mapping at 7T.

2832. Practical Vector B1 Mapping at 7T

Douglas Kelley1,2, Janine Lupo2

1Applied Science Laboratory, GE Healthcare, San Francisco, CA, United States; 2Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, CA, United States

Compensation of B1 variations in vivo requires mapping both the magnitude and the phase of each channel's RF magnetic field. Since the field distribution is strongly dependent on the specific size, shape, and positioning of the tissue, such mapping must be made for each subject. We present a practical method for acquiring these maps within 10 minutes in phantoms and human subjects at 7T.

2833. Compressive B1+ Mapping: Towards Faster Transmit Coil Sensitivity Mapping

Mariya Doneva1, Kay Nehrke2, Alfred Mertins1, Peter Börnert2

1Institute for Signal Processing, University of Lübeck, Lübeck, Germany; 2Philips Research Europe, Germany

The potential to accelerate the B1+ mapping measurement by means of compressed sensing (CS) was investigated. Joint sparsity constraint accounting for the common sparsity support in different TX channels, and higher dimensional undersampling space, also including the coil dimension, allow for considerable acceleration even for the low resolution data acquired in B1+ mapping. The basic feasibility of the proposed method is evaluated on simulations and in vivo data from a 3T 8-channel parallel transmit system.

2834. Simultaneuous B0 and High Dynamic Range B1 Mapping Using an Adiabatic Partial Passage Pulse

Kim Shultz1, Greig Scott1, Joelle Barral1, John Pauly1

1Electrical Engineering, Stanford University, Stanford, CA, United States

We present a simultaneous δ B0 and high-dynamic range B1 mapping technique using an adiabatic partial passage pulse. The double angle method, the gold standard for B1 mapping, requires 66% longer to acquire the same B1 range. The high dynamic range is useful for mapping the fields from ablation wires or surface coils, where significant B0 variation will also be present.

2835. Fast B1+ Mapping with Validation for Parallel Transmit System in 7T

Joonsung Lee1, Borjan Gagoski1, Rene Gumbrecht1,2, Hans-Peter Fautz3, Lawrence L. Wald4,5, Elfar Adalsteinsson1,5

1Electrical engineering and computer science, Massachusetts Institute of Technology, Cambridge, MA, United States; 2Physics, Friedrich-Alexander-University Erlangen, Erlangen, Germany; 3Siemens Healthcare, Erlangen, Germany; 4Department of Radiology, A. A. Martinos Center for Biomedical Imaging, Cambridge, MA, United States; 5Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, United States

We present a fast B1+ mapping method for parallel transmit system and validate the performance on water phantom in 7T. The measured flip angle matches with the flip angle simulated by the Bloch equation.

2836. Image-Guided Radio-Frequency Gain Calibration for High-Field MRI

Elodie Breton1, KellyAnne McGorty1, Graham C. Wiggins1, Leon Axel1, Daniel Kim1

1Research Radiology - Center for Biomedical Imaging, New York University Langone Medical Center, New York, NY, United States

The purpose of this study was to develop a rapid, image-guided RF transmitter gain calibration procedure for high-field MRI and evaluate its performance through phantom and in vivo experiments at 3T and 7T. Using a single-shot TurboFLASH pulse sequence, a series of “saturation-no-recovery” images was acquired by varying the flip angle of the preconditioning pulse. In the resulting images, the signal null occurs in regions where the flip angle of the preconditioning pulse is 90°, and the mean signal within a region-of-interest can be plotted as a function of the nominal flip angle to quantitatively calibrate the RF transmitter gain.

2837. No Inversion Double Angle Look-Locker (NiDALL) for Flip Angle Mapping

Trevor Wade1,2, Charles McKenzie1,3, Brian Rutt4

1Imaging Research Laboratories, Robarts Research Institute, London, ON, Canada; 2Biomedical Engineering, The University of Western Ontario, London, ON, Canada; 3Medical Biophysics, The University of Western Ontario, London, ON, Canada; 4Diagnostic Radiology and Richard M Lucas Center for Imaging, Stanford University, Stanford, CA, United States

The double angle Look-Locker method is an efficient 3D method of mapping transmit B1 inhomogeneity. It makes uses inversion pulses and samples the recovering magnetization using SPGR trains at two different angles. This leads to two time constants that can be combined to find the achieved flip angle. If the SPGR trains at the two angles are interleaved the inversion pulses can be omitted entirely, and the same information can still be extracted. This reduces SAR, simplifies data analysis and still yields nearly the same performance in terms of measuring the flip angle.

2838. Electromagnetic and Thermal Simulations of Experimentally-Verified B1 Shimming Scheme with Local SAR Constrains

Lin Tang1, Tamer S. Ibrahim2

1School of Electrical and Computer Engineering, University of Oklahoma; 2Departments of Bioengineering and Radiology, Univeristy of Pittsburgh, Pittsburgh, PA, United States

In this work, using 3D numerical simulations and verifications with a 7T scanner equipped with a transmit array system we conduct a comprehensive study using B1 shimming for potential 7T whole-body applications. Different from previous works [2], this study includes the optimizations of the B1+ field, local/average SAR and the resulting temperature elevation in the tissue.

2839. Simulation and Comparison of B1+ Mapping Methods at 3T

Christopher Thomas Sica1, Zhipeng Cao1, Sukhoon Oh1, Christopher M. Collins1

1Penn State College of Medicine, Hershey, PA, United States

RF inhomogeneity greatly affects the quality of MR imaging at high field strength, and compensation methods typically require accurate B1+ maps for optimum performance. Comparison of B1+ mapping methods based on experimental results alone is limited by lack of knowledge of the true B1+ field distribution. MRI simulation allows for comparison of the true, input B1+ field distribution with a simulated map. This study simulates AFI and a flip angle series method at 3T, utilizing MRI and electromagnetic field simulations. The simulation maps correspond closely to the input B1+ and one another. Experimental maps deviate significantly from one another.

B1 Mapping

Hall B Tuesday 13:30-15:30

2840. 3D Phase Sensitive B1 Mapping

Steven Paul Allen1, Glen R. Morrell2, Brock Peterson1, Daniel Park1, Josh Kaggie2, Ernesto Staroswiecki3, Neal K. Bangerter1

1Department of Electrical and Computer Engineering, Brigham Young University, Provo, UT, United States; 2Department of Radiology, University of Utah, Salt Lake City, UT, United States; 3Department of Radiology, Stanford University, Stanford, CA, United States

Accurate quantification of tissue sodium concentration is an important component of several potential applications of sodium MRI. Quantitative analysis of sodium concentrations requires accurate measurement of B1. However, the low SNR typical in sodium MRI makes accurate B1 mapping in a reasonable time challenging. Phase-sensitive B1 mapping techniques are particularly robust in low SNR environments. In this work, we apply phase sensitive B1 mapping to sodium MRI, and compare it to a standard dual angle B1 mapping method. The phase sensitive method is shown to perform much better than the dual angle method, allowing rapid acquisition of reliable sodium B1 maps.

2841. Image Inhomogeneity Correction in Human Brain at High Field by B1+ and B1- Maps

Hidehiro Watanabe1, Nobuhiro Takaya1, Fumiyuki Mitsumori1

1Environmental Chemistry Division, National Institute for Environmental Studies, Tsukuba, Ibaraki, Japan

We propose a correction method of image inhomogeneity at high field. The inhomogeneity is originated from B1- and measurable B1+. We confirmed that a ratio map of B1- to B1+ (ρ) has a similar spatial pattern throughout human various brains from experimental results. The ratio map ρ in human brain was calculated from B1+ maps and images obtained with adiabatic pulses. Then, B1- was calculated by ρ× B1+. Homogeneous intensity was achieved in the corrected images by B1+ and B1-. Water fractions in gray and white matters obtained from corrected M0 image were in good agreement with reported values.

2842. Signal to Noise Ratio Analysis of Bloch-Siegert B1+ Mapping

Mohammad Mehdi Khalighi1, Laura I. Sacolick2, Brian K. Rutt3

1Applied Science Lab, GE Healthcare, Menlo Park, CA, United States; 2Imaging Technologies Lab, General Electric Global Research, Garching b. Munchen, Germany; 3Department of Radiology, Stanford University, Stanford, CA

The Bloch-Siegert method (BS) has been recently introduced as a fast, robust and accurate method for B1+ mapping. To compare it with other existing methods, we derived analytical expressions for SNR in BS, Actual Flip Angle Imaging (AFI) and Double Angle (DA) B1+ maps. Both theoretical and experimental comparisons show that the BS method has a higher SNR at low flip angles than the other methods, despite the shorter scan time of the BS method, making it a promising choice for B1+ mapping for parallel transmit pulse design, especially in situations where there is highly non-uniform B1+ across the object.

2843. Sa2RAGE - A New Sequence for Rapid 3D B1+-Mapping with a Wide Sensitivity Range

Florent Eggenschwiler1, Arthur Magill1,2, Rolf Gruetter1,3, José P. Marques1,2

1EPFL, Laboratory for Functional and Metabolic Imaging, Lausanne, Vaud, Switzerland; 2University of Lausanne, Department of Radiology, Lausanne, Vaud, Switzerland; 3Universities of Geneva and Lausanne, Department of Radiology, Switzerland

Sa2RAGE is based on the rapid acquisition of two images with low flip angles just before and after a saturation pulse. The ratio of the signals from the images can be linked to a specific B1+. Optimization of the sequence parameters allowed the derivation of a protocol that performs 3D B1+-mapping in ~30s (matrix size 64x64x16) with limited T1 dependence. Experimental work showed the accuracy of the B1+-mapping over a 10 fold range of B1+. In-vitro and in-vivo B1+ maps were performed to demonstrate the applicability of the method on the context of parallel transmission.

2844. Smoothing and Interpolation of In-Vivo B1+ Images

Andreas Petrovic1,2, Yiqiu Dong3, Stephen Keeling3, Rudolf Stollberger1

1Institute of Medical Engineering, University of Technology Graz, Graz, Austria; 2Ludwig Boltzmann Institute for Clinical Forensic Imaging, Graz, Austria, Austria; 3University of Graz

MR images at high field strengths (≥1.5T) suffer from artifacts caused by the inhomogeneity of the RF excitation field B1+ in the human body. Measurements of B1+ can be used for the correction of those artifacts. However, these B1+-images suffer from perturbations themselves and have to be smoothed and interpolated. In this work a new variational approach for smoothing is compared to a standard median filter for test images, as well as real in-vivo data. Simulations show that the variational approach combined with an outlier suppression algorithm outperforms the median filter in terms of accuracy and precision. In contrast to the median filter the variational approach produces very smooth results that are physically likely.

2845. Flow, Chemical Shift, and Phase-Based B1 Mapping

W Thomas Dixon1, Laura Sacolick2, Florian Wiesinger2, Mika Vogel2, Ileana Hancu1

1GE Global Research Center, Niskayuna, NY, United States; 2GE Global Research Center, Munich, Germany

B1 maps help scan set up and then aid in extracting quantitative results. Maps can be made by comparing either amplitudes or phases of two different images. Phase methods, with no waiting for T1, are fast. Phase avoids T1 issues but what about phase effects from flow and the chemical shift of fat? With a Bloch-Siegert, phase-based method, steady 0.5 m/s flow shifts phase 120o but leaves calculated B1 unchanged. Similarly, oil and water indicate the same B1 regardless of the fat-water phase difference. These results portend robust, phase-based B1 maps.

2846. Small Animal MR Imaging Using a 3.0 Tesla Whole Body Scanner: Rapid B1+ Field Mapping for Quantitative MRI

Ryutaro Nakagami1,2, Masayuki Yamaguchi1, Akira Hirayama1,3, Akira Nabetani3, Atsushi Nozaki3, Takumi Higaki4,5, Natsumaro Kutsuna4,5, Seiichiro Hasezawa4,5, Hirofumi Fujii1,5, Mamoru Niitsu6

1Functional Imaging Division, National Cancer Center Hospital East, Kashiwa, Chiba, Japan; 2Graduate School of Human Health Sciences, Tokyo Metropolitan University, Arakawa, Tokyo, Japan; 3GE Healthcare Japan, Ltd., Hino, Tokyo, Japan; 4Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba, Japan; 5Institute for Bioinformatics Research and Development, Japan Science and Technology Agency, Chiyoda, Tokyo, Japan; 6Faculty of Health Sciences, Tokyo Metropolitan University, Arakawa, Tokyo, Japan

There has been growing interest in MR imaging studies of small animal models of human diseases as small animal MRI systems using a combination of 3.0 Tesla whole-body scanners and highly sensitive solenoid coils, which provides high spatial resolution and high sensitivity, as they are preferable for translational research. In this study, we demonstrate the feasibility of these MRI systems for quantitative MRI research by showing B1+ homogeneity in the mouse brain. In vivo B1+ maps were obtained by a rapid B1+ field mapping technique using a SPGR sequence and a brand-new calculation method for determining the 180° null signal.

2847. Rapid RF Field Mapping Using a Slice-Selective Pre-Conditioning RF Pulse

Sohae Chung1, Daniel Kim1, Elodie Breton1, Leon Axel1

1Radiology, NYU Langone Medical Center, New York, NY, United States

The B1 field uniformity plays an important role in determining the image quality in MRI, since such an RF pulse excitation causes flip angle variations that confound quantitative results. In this study, we describe a novel and efficient method for rapid B1 mapping using a slice-selective pre-conditioning RF pulse followed by TurboFLASH pulse sequence. This method is insensitive to off-resonance, with less than 1.4% B1 measurement error up to 500Hz off-resonance and the total scan time is less than 2s with SR module. Therefore, this method can be used for quantitative MRI applications that require fast B1 calibration.

2848. Fast Phase-Modulated B1+ Mapping in the Low Flip-Angle Regime

Astrid L.H.M.W. van Lier1, Johannes M. Hoogduin2, Dennis J.W. Klomp2, Jan J.W. Lagendijk1, Cornelis A.T. van den Berg1

1Radiotherapy, UMC Utrecht, Utrecht, Netherlands; 2Radiology, UMC Utrecht, Utrecht, Netherlands

In high-field MRI, phased-arrays are used to mitigate RF issues as excitation field inhomogeneities. In order to design RF pulses that can produces a desired excitation field, the B1+ field per coil must be mapped. We show that it is possible to measure B1+ maps for phased arrays in the low flip angle regime using phase-modulation (PMLF). This technique was validated by a contemporary high-flip angle technique and electromagnetic simulations. The advantages of the PMLF technique over the high-flip angle techniques are its low SAR cost and higher speed.

2849. RF Excitation Using Time Interleaved Acquisition of Modes (TIAMO) to Address B1 Inhomogeneity in Highfield MRI

Stephan Orzada1,2, Stefan Maderwald1,2, Benedikt Poser1,3, Andreas K. Bitz1,2, Harald H. Quick1,2, Mark E. Ladd1,2

1Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen, NRW, Germany; 2Department for Radiology and Neuroradiology, University Hospital Essen, Essen, NRW, Germany; 3Donders Institute for Brain, Cognition and Behaviour, Centre for Cognitive Neuroimaging, Radboud University Nijmegen, Nijmegen, Netherlands

Signal dropouts in high and ultra-high field MRI pose a substantial problem. Several approaches including transmit SENSE and RF shimming have been proposed. Here we propose a new imaging scheme to tackle this challenge. Using TIAMO, two or more inhomogeneous images acquired using different RF-transmit modes are combined to one homogeneous image. The cost in time for multiple acquisitions can be partially compensated by using the different acquisitions to generate virtual receive channels in a parallel imaging reconstruction. A mathematical theory is developed, and the results of phantom studies as well as first 7T in vivo abdominal imaging are presented.

2850. Enhanced Parallel Imaging Acceleration with a B1 Accelerated Reconstruction Sequence (BARS)

Gigi Galiana1, Jason P. Stockman1, Robert Todd Constable1

1Diagnostic Radiology, Yale University, New Haven, CT, United States

This work presents an approach to accelerated imaging via RF and surface coil localization using a multiwindow acquisition. The sequence can be described as creating “effective sensitivity profiles” for each acquisition window using the in-plane RF profiles to multiply and sculpt the sensitivity profiles of multichannel receivers. Rectangular RF profiles are chosen so as to efficiently encode along the phase encode-direction, improving the ability to unwrap aliasing caused by extreme undersampling along this direction. We present both numerical studies and experimental verification of the approach.

2851. Comparison of Different Methods for B1+/flip Angle and Reception Sensitivity Mapping

Valentina Hartwig1,2, Nicola Vanello3, Giulio Giovannetti1, Maria Fillomena Santarelli1, Luigi Landini3

1Institute of Clinical Physiology, CNR, Pisa, Italy, Italy; 2Department of Electrical Systems and Automation, University of Pisa, Pisa, Italy, Italy; 3Department of Information Engineering, University of Pisa, Pisa, Italy, Italy

Knowledge of transmission field B1+, and reception sensitivity maps is important in high field (>=3T) human Magnetic Resonance (MR) imaging for several aspects: these include post acquisition correction of intensity inhomogeneities, that may affect the quality of images, and modelling and design of radiofrequency (RF) coils and pulses. Moreover, in recent works, it has been demonstrated that B1 maps can be used for the direct calculation of tissues electrical parameters and for estimating the local Specific Absorption Rate (SAR) in vivo. In this study a comparison among known methods for B1+/flip angle and reception sensitivity mapping is introduced.

2852. Simulataneous B1 and B0 Mapping at 7T

Walter RT Witschey1, Ravinder Reddy1, Mark A. Elliott1

1Radiology, University of Pennsylvania, Philadelphia, PA, United States

A modification of the actual flip angle (AFI) method for measuring B1 is presented which simultaneously acquires spatial maps of both B0 and B1, allowing for accurate calculation of the radiofrequency field in the presence of off-resonance effects. An analytical expression for the actual B1 field is derived, given the apparent flip angle and the B0 map. Application of the new method is demonstrated at 7 tesla in phantom images.

B1 Insensitive RF

Hall B Wednesday 13:30-15:30

2853. BIR-4 Based B1 and B0 Insensitive Velocity Selective Pulse Trains

Eric C. Wong1, Jia Guo2

1Radiology and Psychiatry, UC San Diego, La Jolla, CA, United States; 2Bioengineering, UC San Diego

The BIR-4 pulse was recently shown to be useful for B1 and B0 insensitive T2 preparation. We report here an extension of this concept that includes the use of symmetrical gradient pulses inserted at the zero points of the BIR-4 pulse to impart velocity selectivity. The resulting velocity selective module is time efficient, and has better B1 insensitivity than existing methods based on adiabatic double spin echoes. Application to velocity selective arterial spin labeling is demonstrated.

2854. Broadband, Shallow Tip NMR Pulse Design Providing Uniform Tipping in Inhomogeneous RF Fields

Hui Liu1, Gerald Matson1,2

1CIND, Veterans Affairs Medical Center, San Francisco, CA, United States; 2Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA, United States

Although high-field MRI offers increased signal-to-noise (S/N), the non-uniform tipping produced by conventional RF pulses leads to spatially dependent contrast and sub-optimal S/N, thus complicating the interpretation of the MR images. The aim of this research was to develop broadband RF pulses with immunity to B1 inhomogeneity. To accomplish this, we developed an optimization routine based on optimal control theory to design RF pulses with a desired range of immunity to B1 inhomogeneity and to resonance offset. The resulting pulses were more efficient than analogous pulses in the literature. These pulses have promise for certain MRI experiments at high field.

2855. Adiabatic Pulses Revisited Through Averaging

Bahman Tahayori1,2, Leigh Andrea Johnston1,2, Peter Mark Farrell1,2, Iven Michiel Yvonne Mareels1,2

1EEE Department, The University of Melbourne, Melbourne, Victoria, Australia; 2NICTA Victoria Research Laboratory, Melbourne, Australia

In this paper, the Bloch equation is scaled and averaged consequently to find the magnetization behaviour in a simple way with a negligible error for adiabatic passages. The novel framework presented here may be used to optimise the modulation functions of the adiabatic passages.

2856. Hyperbolic Secant Parameter Optimization for Non-Selective Inversion at 7 T

Jay Moore1,2, Marcin Jankiewicz1,3, Adam W. Anderson1,4, John C. Gore1,4

1Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States; 2Department of Physics and Astronomy, Vanderbilt University, Nashville, TN, United States; 3Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, United States; 4Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, United States

Results include 3D δB0 and B1+ field maps in the human brain at 7 T. Hyperbolic secant pulses with a range of bandwidths are evaluated for non-selective inversion uniformity in this context. Numerical optimization of hyperbolic secant waveform parameters (β and μ) is shown to result in noticeably improved inversion uniformity as compared to pulses with the same bandwidth and μ=5.

2857. B1 Insensitive Genetically Altered Refocusing Pulses for Ultrahigh Field Spin Echo Imaging

Aaron Christopher Hurley1,2, Andrew Peters1, Uwe Aickelin2, Li Bai2, Penny Anne Gowland1

1SPMMRC, University of Nottingham, Nottingham, Nottinghamshire, United Kingdom; 2Computer Science, University of Nottingham, United Kingdom

Urgurbil et al. proposed the use of a Numerically Optimised Modulation (NOM) scheme to improve the adiabaticity over the whole length of a BIR4 pulse and this method provides better performance for shorter pulses. NOM resamples the AM and FM functions with reference to the adiabatic condition and is restricted to looking at on-resonance effects. Following from this work, we attempted to optimize the resampling function via a Genetic Algorithm. The evaluation function considers B1 and B0 inhomogeneities to tailor the optimization to 7T conditions, requiring the study of off-resonance behaviour.

2858. A Slice-Selective B1+-Insensitive Composite Pulse Design for Improved Excitation Uniformity at 7 T

Jay Moore1,2, Marcin Jankiewicz1,3, Adam W. Anderson1,4, John C. Gore1,4

1Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States; 2Department of Physics and Astronomy, Vanderbilt University, Nashville, TN, United States; 3Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, United States; 4Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, United States

Numerical optimization of the amplitudes and phases of a series of block-shaped sub-pulses was used to generate a 1.2 kHz bandwidth, 90° excitation pulse that is highly insensitive to the variations in the RF transmission field observed in the human brain at 7 T. This pulse serves as an example of the value of RF pulse design in providing an effective and cost-free alternative to technologies such as multiple-channel transmission for the purpose of achieving flip-angle uniformity at high field.

2859. An Optimized Composite Refocusing Pulse for Ultra-High Field MRI

Marcin Jankiewicz1,2, Jay Moore1,3, Adam W. Anderson1,4, John C. Gore1,4

1Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States; 2Department of Radiology, Vanderbilt University, Nashville, TN, United States; 3Department of Physics, Vanderbilt University; 4Department of Biomedical Engineering, Vanderbilt University

A design of a composite refocusing pulse suitable for use in human imaging at 7T is presented here. With the assumption that it is preceded by a slice-selective excitation, the refocusing solution is immune to inhomogeneities within a predefined space of B1+ and δB0 values for 7T human head imaging.

2860. Slice-Selective Broadband Refocusing Pulses with B1 Immunity

Martin Janich1,2, Rolf F. Schulte2, Markus Schwaiger3, Steffen J. Glaser1

1Department of Chemistry, Technische Universität München, Munich, Germany; 2Imaging Technologies, GE Global Research, Munich, Germany; 3Institute for Nuclear Medicine, Technische Universität München, Munich, Germany

Broadband radio-frequency pulses are of great interest for reducing chemical shift displacements, anomalous J coupling, and increasing spectral selectivity. In this study broadband refocusing pulses with immunity to B 1 variations are designed using optimal control theory. The pulse design concentrates on posing least constrains on the optimization. The refocusing pulse presented here reaches a ratio of pulse bandwidth to peak RF amplitude of 2.1 and immunity of -10 % to +20 % B 1 variations. The optimized pulse is compared to a broadband SLR pulse, and validated experimentally.

2861. B1 Insensitive MLEV-4 Pulse Sequence for T2-Prep

Mitsuharu Miyoshi1, Naoyoki Takei1, Masaaki Akahane2, Yasushi Watanabe3, Tetsuji Tsukamoto1

1Japan Applied Science Laboratory, GE Healthcare Japan, Hino, Tokyo, Japan; 2Radiology, University of Tokyo, Tokyo, Japan; 3Radiological Technology, University of Tokyo Hospital, Tokyo, Japan

T2-prep is important for cardiovascular applications. However, because of B1 inhomogeneity on 3T, inhomogeneous signal loss occurs. T2-prep often uses MLEV-4 type sequence. In this study, B1 insensitive MLEV-4 type preparation pulse was designed and B1 and flow sensitivity were measured. Flip angle of MLEV-4 sequence was modified to (90x,140y,-200y,-140y,200y,-90x). Because at least two of the refocus pulses became near to 180 degree between -20% and +40% of delta B1, magnetizations were refocused correctly and became insensitive to B1 inhomogeneity. This preparation pulse suppressed flow signal and can also be used as flow saturation preparation pulse.

2862. Zoomed Spin-Echo Echo Volumar Imaging of the Mouse Brain in Vivo Using Adiabatic Pulses

Julien Flament1, Sidi Mohamed Ould Ahmed Ghaly1, Benjamin Marty1, Céline Giraudeau1, Sébastien Mériaux1, Gilles Bloch1, Denis Le Bihan1, Franck Lethimonnier1, Julien Valette1, Fawzi Boumezbeur1

1NeuroSpin, I²BM, Commissariat à l'Energie Atomique, Gif-sur-Yvette, France

Many developments in the field of fast preclinical imaging are based on EVI sequences. We propose here an optimized protocol designed for preclinical in vivo imaging combining a quadrature surface coil with a zoomed Spin Echo EVI sequence using two orthogonal slice-selective adiabatic pulses (designated as ZEVIA) for volume selection. Brain coverage and time resolution are improved substantially without any drawbacks in the mouse brain in vivo at 7T.

2863. Improved Non-Selective T2-Prep with Adiabatic Vs. Composite Pulses for Whole-Heart T2w Edema Imaging in Mice

Ronald J. Beyers1, Yaqin Xu1, Michael Salerno2, Stuart S. Berr3, Craig H. Meyer1, Frederick H. Epstein1,3, Brent A. French1,2

1Biomedical Engineering, University of Virginia, Charlottesville, VA, United States; 2School of Medicine, University of Virginia, Charlottesville, VA, United States; 3Radiology, University of Virginia, Charlottesville, VA, United States

T2w MRI of the heart allows imaging post-infarct myocardial edema -- a key indicator of area at risk and possibly salvagable tissue. For high-field, 7 Tesla imaging in mice, we compared composite and adiabatic RF pulses in T2-Prep sequences. By simulation, phantom and in vivo imaging, we developed a flexible adiabatic T2-Prep method for whole-heart imaging of myocardial edema from onset within hours through resolution past the 20 day point.

MRI of Conductivity

Hall B Thursday 13:30-15:30

2864. Propagating RF Phase: A New Contrast to Detect Local Changes in Conductivity

Astrid L.H.M.W. van Lier1, Alexander J. Raaijmakers1, David O. Brunner2, Dennis W.J. Klomp3, K. P. Pruessmann2, Jan J.W. Lagendijk1, Cornelis A.T. van den Berg1

1Radiotherapy, UMC Utrecht, Utrecht, Netherlands; 2Institute for Biomedical Engineering, ETH Zurich, Zurich, Switzerland; 3Radiology, UMC Utrecht, Utrecht, Netherlands

From basic EM (electromagnetic) theory we know that the wavelength, thus the propagating phase, depends on the permitivity and conductivity. Analysis, based on simulations, showed that local changes in the conductivity, have the largest effect on the propagating phase in the physiological range. We demonstrated that it is possible to measure the effect both in phantoms and in vivo, with results comparable to results of EM simulations. This new contrast mechanism might be useful for the detection of conducting malignancies, such as breast tumours.

2865. In Vivo Quantitative Conductivity Imaging Based on B1 Phase Information

Tobias Voigt1, Ulrich Katscher2, Olaf Doessel1

1Institute of Biomedical Engineering, University of Karlsruhe, Karlsruhe, Germany; 2Philips Research Europe, Hamburg, Germany

In this work, in vivo conductivity values of human tissue are obtained using standard MRI. Conductivity is a new and quantitative contrast for MRI. It can be obtained in 3D within 5 min by means of phase-based reconstruction presented in this abstract. Phase-based reconstruction is motivated analytically and validated in FDTD simulations and in in vivo experiments.

2866. Estimation of the Anisotropy of Electric Conductivity Via B1 Mapping

Ulrich Katscher1, Tobias Voigt2, Christian Findeklee1

1Philips Research Europe, Hamburg, Germany; 2Institute of Biomedical Engineering, University of Karlsruhe, Karlsruhe, Germany

Electric conductivity might be used as diagnostic information due to its ability to reflect the grade of tissue damage. In general, the conductivity is given by a tensor including anisotropic cases of conductivity, as can be found in vivo in tissue with preferred cell direction like muscles or nerves. Measuring conductivity, characterizing the underlying cell structure, might increase diagnostic information. The recently presented “Electric Properties Tomography” (EPT) is able to determine tissue conductivity in vivo by post-processing B1 maps. This study demonstrates the ability of EPT to estimate also the anisotropy of the conductivity using an electrically anisotropic phantom.

Parallel Imaging

Hall B Monday 14:00-16:00

2867. Title: Reconstruction of Sparsely-Sampled Dynamic MRI Data Using Iterative “Error Energy” [1] Reduction

Sumati Krishnan1, David Moratal2, Lei-Hou Hamilton3, Senthil Ramamurthy4, Marijn Eduard Brummer4

1Emory University, Atlanta, GA, United States; 22Universitat Politècnica de València, Valencia, Spain; 3Georgia Institute of Technology, Atlanta, GA, United States; 4Emory University, Atlanta, GA, United States

A well-known reconstruction method, based on “error energy” reduction [1], is adapted to sparsely sampled dynamic cardiac MRI. Inherent temporally band-limited properties of known static regions in the FOV, are used to recover additional resolution from information embedded in the acquired k-t samples. The algorithm converges as the error due to residual dynamic content in the static region is minimized. Reconstructions equivalent to direct matrix-inversion [2] are achieved with significantly reduced computational costs, while convergence properties are related to the sampling patterns. The proposed iterative method has potential applications for a variety of non-Cartesian grids as well as sparse-sampling patterns.

2868. Null Space Imaging: A Novel Gradient Encoding Strategy for Highly Efficient Parallel Imaging

Leo Tam1, Jason Peter Stockmann1, Robert Todd Constable, 12

1Biomedical Engineering, Yale University, New Haven, CT, United States; 2Diagnostic Radiology & Neurosurgery, Yale University, New Haven, CT, United States

Null Space Imaging (NSI) defines nonlinear encoding gradients to complement the spatial localization abilities of a parallel receiver array. To complement coil sensitivities, gradients should encode where coil sensitivities poorly distinguish signal. The singular value decomposition analyzes coil sensitivities to generate a complete basis set of vectors spanning the null space of sensitivities. By interpreting the orthogonal vectors in the null space as a complementary gradient set, NSI enables highly accelerated (R=16) parallel imaging as demonstrated by simulated spin echo experiments. NSI suggest complementary gradient design is a powerful concept for parallel imaging requiring only a limited set of receivers.

2869. GPU Accelerated Iterative SENSE Reconstruction of Radial Phase Encoded Whole-Heart MRI

Thomas Sangild Sørensen1, Claudia Prieto2, David Atkinson3, Michael Schacht Hansen4, Tobias Schaeffter2

1Aarhus Univeristy, Aarhus N, Denmark; 2King's College London; 3University College London; 4National Institutes of Health

Isotropic whole-heart imaging has become an important protocol in simplifying cardiac MRI. The acquisition time can however be a prohibiting factor. To reduce acquisition times a 3D scheme combining Cartesian sampling in the readout direction with radial sampling in the phase encoding plane was recently suggested. It allows high undersampling factors in the phase encoding plane when obtaining data with a 32-channel coil array and employing non-Cartesian iterative SENSE for reconstruction. Unfortunately this reconstruction is a time consuming process. We demonstrate however that the reconstruction time can be brought to a clinically acceptable level using commodity graphics hardware (GPUs).

2870. Calibrationless Parallel Imaging Reconstruction by Structured Low-Rank Matrix Completion

Michael Lustig1,2, Michael Elad3, John Mark Pauly2

1Electrical Engineering and Computer Science, University of California Berkeley, Berkeley, CA, United States; 2Electrical Engineering, Stanford University, Stanford, CA, United States; 3Computer Science, Technion IIT, Haifa, Israel

A new method for parallel imaging that requires no special autocalibration lines or calibration scans is presented. Instead, the method jointly calibrates, and synthesizes missing data from the entire acquired k-space. The proposed method is based on low-rank matrix completion, which is an extension of the compressed sensing theory to matrices. It is implemented by iterative singular value thresholding. The method can be used to reconstruct undersampled data, to generate calibration data for GRAPPA-like methods, or just to improve calibration when the calibration area is too small.

2871. Context Based GRAPPA Reconstruction Using a Small Kernel

Berkay Kanberoglu1, Lina J. Karam1, Josef P. Debbins2

1Electrical Engineering, Arizona State University, Tempe, AZ, United States; 2Keller Center for Imaging Innovation, Barrow Neurological Institute, Phoenix, AZ, United States

For GRAPPA reconstruction, large kernel sizes can be disadvantageous in some cases due to the large number of GRAPPA coefficients. A system like this needs a large number of equations to construct an over-determined system. Small kernel sizes can be advantageous when there is a small number of equations. Proposed algorithm employs a small kernel size and a clustering method to produce more than one set of GRAPPA weights within a slice.

2872. Sinusoidal Perturbations Improve the Noise Behavior in Parallel EPI

Maximilian Haeberlin1, Bertram Wilm1, Christoph Barmet1, Sebastian Kozerke1, Georgios Katsikatsos1, Klaas Paul Pruessmann1

1Department of Electrical Engineering, ETH Zurich, Zurich, Switzerland

Perturbing EPI phase encoding lines in a sinusoidal fashion improves the g-factor map for SENSE reconstruction. Concurrent field monitoring ensures artifact-free reconstruction for 3-fold undersampled data.

2873. Non-Linear Inversion in Parallel MRI: Considerations on Noise Amplification in the Joint Estimation of Image and Coil Sensitivities

Julien Sénégas1, Martin Uecker2

1Philips Research Europe, Hamburg, Germany; 2Biomedizinische NMR Forschungs GmbH, Göttingen, Germany

Recently, iterative joint estimation algorithms have been proposed to reconstruct aliasing free images and coil sensitivities in a single step from self-calibrating sampling trajectories such as Cartesian with variable density. Due to the non-linearity of the reconstruction method, their behavior with respect to noise amplification is more difficult to predict. In this work, we extend the non-linear inversion algorithm (NLINV) by incorporating the noise covariance of the coil array in the minimization function and by applying additional regularization for the coil sensitivities, both with the aim of improving the SNR of the reconstructed image. We present detailed results on the noise amplification properties of this joint reconstruction scheme and evaluate the proposed algorithm in vivo.

2874. Optimally Regularized GRAPPA/GROWL with Experimental Verifications

Wei Lin1, Feng Huang1, Hu Cheng2, Yu Li1, Arne Reykowski1

1Advanced Concepts Development, Invivo Corporation, Philips Healthcare, Gainesville, FL, United States; 2Indiana University, Bloomington, IN, United States

The performance of GRAPPA-based parallel imaging methods can suffer when the size of the auto-calibration signal (ACS) region becomes small. Based on an analysis of condition number for GRAPPA calibration equation, an optimal Tikhonov regularization factor is proposed to improve the quality of image reconstruction. Alternatively, an optimal amount of noise can be added to the ACS data to stabilize the system. The technique was applied to both GRAPPA and GRAPPA operator for wider radial bands (GROWL), a self-calibrated radial parallel imaging methods. Results show that minimal reconstruction errors are always obtained with the proposed automatic regularization scheme.

2875. Iterative Approach to Atlas Based Sparsification of Image and Theoretical Estimation (Iterative ABSINTHE)

Eric Y. Pierre1, Nicole Seiberlich2, Stephen Yutzy1, Vikas Gulani2, Felix Breuer3, Mark Griswold2

1Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States; 2Departments of Radiology, Case Western Reserve University, Cleveland, OH, United States; 3Research Center Magnetic Resonance Bavaria e.V., Würzburg, Germany

The ABSINTHE technique has been shown to allow better GRAPPA reconstructions at high undersampling factors by sparsifying the undersampled image to reconstruct. This study seeks to further increase the effectiveness of ABSINTHE by improving the PCA approximation which generates this sparse image. After a first standard ABSINTHE estimation, iterative ABSINTHE uses fully-sampled eigenvectors to generate an even sparser representation of the undersampled data. The efficacy of this technique for simulated data and longitudinal simulations is demonstrated, and an improved image quality is shown for iterative ABSINTHE in comparison to the standard ABSINTHE and GRAPPA techniques.

2876. Tailored 3D Random Sampling Patterns for Nonlinear Parallel Imaging

Florian Knoll1, Christian Clason2, Rudolf Stollberger1

1Institute of Medical Engineering, Graz University of Technology, Graz, Austria; 2Institute for Mathematics and Scientific Computing, University of Graz, Graz, Austria

The idea of randomized 3D Cartesian subsampling was proposed within the framework of compressed sensing. The optimal design of these sampling patterns is an open problem, especially the determination of the correct ratio of low to high frequency sample points. The goal of this work is to show that it is possible to construct an adapted random sampling pattern by using measured k-space data as a reference, which automatically ensures an appropriate distribution of sample points for different types of scans. In this work, these sampling patterns were used in combination with regularized nonlinear inversion for parallel imaging. This allows the use of very high acceleration factors while still yielding images with excellent image quality.

2877. Fast Non-Iterative JSENSE: From Minutes to a Few Seconds

Feng Huang1, Wei Lin1, Yu Li1, Arne Reykowski1

1Invivo Corporation, Gainesville, FL, United States

It has been shown that joint image reconstruction and sensitivity estimation in SENSE (JSENSE) can improve image reconstruction quality when acceleration factor is high. However, existing methods for JSENSE need long reconstruction time and/or optimal termination condition, which have hindered its clinical applicability. In this work, a fast non-iterative JSENSE technique, based on pseudo full k-space, is proposed to improve the clinical applicability of JSENSE. Using the proposed method, the computation time for sensitivity maps could be reduced from minutes to a few seconds without degrading the image quality.

2878. Parallel Imaging Using a 3D Stack-Of-Rings Trajectory

Holden H. Wu1,2, Michael Lustig2,3, Dwight G. Nishimura2

1Cardiovascular Medicine, Stanford University, Stanford, CA, United States; 2Electrical Engineering, Stanford University, Stanford, CA, United States; 3Electrical Engineering and Computer Science, University of California at Berkeley, Berkeley, CA, United States

We present an efficient parallel imaging strategy for the 3D stack-of-rings non-Cartesian trajectory to further enhance its flexible trade-offs between image quality and scan time. Due to its distinct geometry, parallel imaging reconstruction for the 3D stack-of-rings trajectory can be decomposed directly into a series of 2D Cartesian sub-problems, which can be solved very efficiently. Experimental results demonstrate that a 2-fold reduction in scan time can be achieved on top of the 2-fold speedup already offered by the rings (compared to Cartesian encoding). Our approach combines the acceleration from both non-Cartesian sampling and parallel imaging in an efficient and easily deployable algorithm.

2879. Coil-By-Coil Vs. Direct Virtual Coil (DVC) Parallel Imaging Reconstruction: An Image Quality Comparison for Contrast-Enhanced Liver Imaging

Philip James Beatty1, James H. Holmes2, Shaorong Chang, Ersin Bayram, Jean H. Brittain3, Scott B. Reeder4

1Applied Science Laboratory, GE Healthcare, Menlo Park, CA, United States; 2Applied Science Laboratory, GE Healthcare, Waukesha, WI, United States; 3Applied Science Laboratory, GE Healthcare, Madison, WI, United States; 4Departments of Radiology and Medical Physics, University of Wisconsin-Madison, Madison, WI, United States

Compared to coil-by-coil reconstructions, Direct Virtual Coil (DVC) parallel imaging reconstructions improve computational efficiency for high channel count coil arrays by only synthesizing unacquired data for one virtual coil instead of synthesizing a separate dataset for each physical coil. In this study, image quality is compared between coil-by-coil and DVC parallel imaging reconstructions in the context of contrast-enhanced liver imaging. Results showed no significant difference in the image quality achieved by the two reconstruction methods.

2880. Towards a Geometry Factor for Projection Imaging with Non-Linear Gradient Fields

Jason P. Stockmann1, Gigi Galiana2, Robert Todd Constable3

1Biomedical Engineering, Yale University, New Haven, CT, United States; 2Diagnostic Radiology, Yale University, New Haven, CT, United States; 3Diagnostic Radiology, Neurosurgery, and Biomedical Engineering, Yale University, New Haven, CT, United States

Conventional parallel imaging performance is assessed either by computing the analytical geometry factor or, if necessary, comparing the SNRs of fully-sampled and undersampled Monte Carlo reconstructions. The empirical g-factor is unsuitable, however, for methods such as O-Space imaging in which non-linear gradients are used to obtain projections of the object. Since O-Space point spread functions are highly variable with position, the g-factor must be corrected for voxel-size in order to distinguish intra-voxel blurring from true noise amplification. This work shows the limited utility of uncorrected empirical g-factors for O-Space imaging and discusses how to compute the PSF for this class of non-linear projection imaging methods.

2881. Selection of Image Support Region and of an Improved Regularization for Non-Cartesian SENSE

Yoon Chung Kim1, Jeffrey Fessler2, Douglas Noll1

1Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States; 2Electrical Engineering, University of Michigan, Ann Arbor, MI, United States

Even though non-Cartesian parallel imaging has demonstrated increasing potential for an acquisition tool in MRI, there are still drawbacks such as reduced SNR and incomplete suppression of the undersampling or aliasing artifact. In suppressing such artifacts, the selection of image support, specifying a reconstruction region of interest is an important factor, due to the complex aliasing pattern associated with undersampling. Proper selection of image support can improve the conditioning of the reconstruction by constraining regions that are known to be zero. In this study, we investigate how the selection of image support region affects the performance of non-Cartesian SENSE reconstruction applied to undersampled spiral k-space data. Considering a potential effect of the sharp edges of a conventional mask on aliasing artifact, we also applied a smoothed mask through an additional regularized term to give smoothness to the mask edges. We tested our hypotheses on masking effects with the simulation and in-vivo human data and our results show that using a moderate size of mask can improve the image quality and the smoothing the mask is effective in suppressing aliasing artifact. Functional MRI result also indicates that softening function further increases the number of activated pixels and tSNR, and reduces image domain error.

2882. Variable-Density Parallel Imaging with Partially Localized Coil Sensitivities

Tolga Çukur1, Juan Santos1, John Pauly1, Dwight Nishimura1

1Department of Electrical Engineering, Stanford University, Stanford, CA, United States

PILS is a very fast reconstruction method for both Cartesian and non-Cartesian sampling; however, it can suffer from residual aliasing artifacts when coupled with variable-density acquisitions. In this work, we propose an improved variable-FOV method that suppresses the aliasing artifacts, while optimally utilizing the densely sampled low-spatial-frequency data. Individual coil images are then linearly combined using data-driven sensitivity estimates. In vivo comparisons with PILS and SENSE are provided.

2883. Synthetic Target Combined with PILS (ST-PILS) for Improving SNR in Parallel Imaging

Meihan Wang1, Weitian Chen2, Michael Salerno1, Peng Hu3, Christopher M. Kramer1, Craig Meyer1

1Biomedical Engineering, University of Virginia, Charlottesville, VA, United States; 2GE; 3Beth Israel Deaconess Medical Center,

The abstract introduces a novel rapid reconstruction algorithm called ST(Synthetic Target)-PILS. It improves the original Synthetic Target method by achieving a higher SNR. We also studied reconstruction speed comparing to coil-by-coil reconstruction.

2884. Iterative IIR GRAPPA: A Novel Improved Method for Parallel MRI

Kaiyu Zheng1, Wendy Ni1, Jingxin Zhang2

1Monash Unversity; 2Department of Electrical and Computer Systems Engineering, Monash University, Clayton, VIC 3800, Australia

GRAPPA proves to be an effective constrained parallel MRI method. However, it does not exploit the acqired data to the utmost.In our investigation to produce a superior parallel Magnetic Resonance Imaging (MRI) reconstruction technique, we propose the novel method of Infinite Impulse Response Iterative GRAPPA (IIR iGRAPPA). This method uses both acquired and reconstructed data points to iteratively interpolate downsampled k-space data, achieving excellent reconstruction quality without the need to acquire much additional data for calibration purposes. Experimental results clearly demonstrate the superiority of the proposed method over the conventional GRAPPA method.

2885. Applying Parallel Imaging for SNR Enhancement

Daniel Stäb1, Christian Ritter1, Dietbert Hahn1, Herbert Köstler1

1Institute of Radiology, University of Wuerzburg, Wuerzburg, Bavaria, Germany

Typically in fast MRI, the measurements are carried out using a high readout bandwidth, leading to a generally low SNR. In this work undersampling k-space, while maintaining the image acquisition time is proposed. Consequently, TR and the signal acquisition time can be raised and the SNR is increased. For image reconstruction, parallel imaging techniques are utilized. As the SNR gain is considerably influenced by the geometry factor crucial investigations are required. g-factors are minimized by homogeneously distributing the phase encoding steps over k-space. Thus, in terms of SNR, the use of additional reference scans or techniques like TGRAPPA, TSENSE and Auto-SENSE is advantageous.

2886. Noise Weighted T2*-IDEAL Reconstruction for Non-Uniformly Under-Sampled k-Space Acquisitions

Curtis Nathan Wiens1, Shawn Joseph Kisch2, Catherine D. G. Hines3, Huanzhou Yu4, Angel R. Pineda5, Philip M. Robson6, Jean H. Brittain7, Scott B. Reeder, 38, Charles A. McKenzie1,2

1Department of Physics and Astronomy, University of Western Ontario, London, Ont, Canada; 2Department of Medical Biophysics, University of Western Ontario, London, Ont, Canada; 3Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States; 4Applied Science Laboratory, GE Healthcare, Menlo Park, CA, United States; 5Department of Mathematics, California State University, Fullerton, CA, United States; 6Department of Radiology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, United States; 7Applied Science Laboratory, GE Healthcare, Madison, WI, United States; 8Department of Radiology, University of Wisconsin-Madison, Madison, WI, United States

Using different undersampling patterns for the non-calibration and calibration echoes has been shown to improve SNR per unit time of Parallel Imaging accelerated IDEAL reconstructions by up to 40%. The different acceleration factors and k-space undersampling patterns result in different noise enhancement in the non-calibration and calibration echoes. In this work the T2*-IDEAL reconstruction is modified to include noise weighting and demonstrate that SNR improves with the modified reconstruction. For 14.2 fold accelerated phantom data, an 11.9% increase in mean SNR for all phantoms and a maximum 27% increase in SNR over a single phantom was measured.

2887. Three-Dimensionally Accelerated Radial Parallel MRI with a 32-Channel Coil System

Olaf Dietrich1, Maria Suttner1, Maximilian F. Reiser1

1Josef Lissner Laboratory for Biomedical Imaging, Department of Clinical Radiology, LMU Ludwig Maximilian University of Munich, Munich, Germany

Established parallel-imaging techniques include the one-dimensional or two-dimensional acceleration of the data acquisition with Cartesian or non-Cartesian trajectories. However, state-of-the-art receiver coil arrays with 32 and more coil elements that are distributed approximately uniformly in space should also enable a three-dimensional parallel-imaging acceleration, i.e. simultaneous sparse sampling in all three k-space directions. The purpose of this study was to demonstrate three-dimensional parallel-imaging acceleration with high acceleration factors up to 32 based on a three-dimensional radial gradient-echo sequence.

2888. A Rapid Self-Calibrating Radial GRAPPA Method Using Kernel Coefficient Interpolation

Noel C. Codella1, Pascal Spincemaille2, Martin Prince2, Yi Wang2

1Physiology, Cornell Weill Medical College, New York, NY, United States; 2Radiology, Cornell Weill Medical College

This work proposes a rapid self-calibrating radial GRAPPA method that eliminates the need to change domains, calculate sensitivity maps, generate synthetic calibration data, or perform extra gridding operations before the derivation of the GRAPPA kernels.

2889. Zoomed GRAPPA (ZOOPPA) for Functional MRI

Robin Martin Heidemann1, Dimo Ivanov1, Robert Trampel1, Fabrizio Fasano2, Josef Pfeuffer3, Robert Turner1

1Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany; 2Fondazione Santa Lucia, Rome, Italy; 3Siemens Healthcare Sector, Erlangen, Germany

The increased SNR of ultra-high field MR scanners permits improved resolution of fMRI acquisitions. Unfortunately, both high field and high resolution amplify artifacts such as geometric distortions and blurring. Parallel imaging and zoomed imaging can each mitigate these effects. However, highly accelerated parallel imaging is affected by residual artifacts, while excessive zooming sacrifices spatial coverage. A robust combination of both methods is optimized here (‘Zoomed imaging with GRAPPA’ - ZOOPPA) to provide high quality single-shot EPI human brain images with reasonable coverage and an isotropic resolution of 0.65 mm.

2890. Conjugate Gradient PINOT Reconstruction with a Fast Initial Estimate

Lei Hou Hamilton1, Benjamin Russell Hamilton1, David Moratal2, Senthil Ramamurthy3, Marijn Brummer3

1School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, United States; 2Universitat Politècnica de València, València, Spain; 3Emory University, United States

PINOT (Parallel Imaging and NOquist in Tandem), a fast imaging method combining SPACE-RIP and Noquist, favorably preserves edge detail at a cost of increased SNR. PINOT involves a large matrix inversion for each read-out coordinate to combine data from all frames and coils. We use iterative conjugate gradient (CG) to reduce this computational burden. An initial estimate based on the projection matrix’s structure allows CG-PINOT to converge quickly. We simulate this CG-initiated PINOT (CGi-PINOT) with phantom and in vivo studies, showing it provides better reconstructed image quality with an order of magnitude less time than direct inversion PINOT.

2891. Computationally Rapid Method for Estimating SNR of Arbitrary Parallel MRI Reconstructions

Curtis Nathan Wiens1, Shawn Joseph Kisch2, Jacob David Willig-Onwuachi3, Charles A. McKenzie1,2

1Department of Physics and Astronomy, University of Western Ontario, London, Ontario, Canada; 2Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada; 3Department of Physics, Grinnell College, Grinnell, IA, United States

Existing approaches for measuring parallel MRI SNR are limited because they are not applicable to all reconstructions, require significant computation time or need repeated image acquisitions. A new SNR estimation approach is proposed that is a hybrid of the two acquisition and multiple pseudo replica methods. The difference of two pseudo-images is used to estimate the noise in the acquisition. This gives a computationally rapid method of measuring SNR from a single acquisition. SNR maps using the two pseudo-image method were compared to pseudo-replica. All tests of the proposed method were on average within ±1.75%.

2892. Virtual Coil Phase Determination Using Region Growing: Description and Application to Direct Virtual Coil Parallel Imaging Reconstruction

Philip James Beatty1, Shaorong Chang2, Ersin Bayram2, Ananth Madhuranthakam3, Huanzhou Yu1, Scott B. Reeder4, Jean H. Brittain5

1Applied Science Laboratory, GE Healthcare, Menlo Park, CA, United States; 2GE Healthcare, Waukesha, WI, United States; 3Applied Science Laboratory, GE Healthcare, Boston, MA, United States; 4Departments of Radiology and Medical Physics, University of Wisconsin-Madison, Madison, WI, United States; 5Applied Science Laboratory, GE Healthcare, Madison, WI, United States

Setting the phase of the virtual coil in the Direct Virtual Coil (DVC) reconstruction technique is both critical to achieving a high quality reconstruction and challenging, especially with high channel count arrays. In this work, a region growing approach to setting the virtual coil phase is described and evaluated in the context of the DVC technique. We demonstrate that the approach is able to generate sensible virtual coil phase even in challenging situations.

2893. Random Phase Modulation of Spatial Aliasing in Temporal Domain for Dynamic MRI

Yu Li1, Feng Huang1, Wei Lin1, Arne Reykowski1

1Advanced Concept Development, Invivo Diagnostic Imaging, Gainesville, FL, United States

In this study, we propose a new k-t space sampling trajectory for parallel dynamic MRI. This method applies random phase modulation to the spatial aliasing of images in temporal domain. As a result, the spatial aliasing induced by k-space undersampling at every time frame has a noise pattern in temporal dimension. By applying a temporal constraint that can be known from the priori knowledge of dynamic MRI data, the noise-like aliasing can be easily removed. This work uses the fMRI and cardiac imaging applications as examples to demonstrate the feasibility of the proposed method.

2894. Rapid 3D Parallel Imaging of Non-Cartesian Data

Nicholas Ryan Zwart1, James Grant Pipe1

1Keller Center for Imaging Innovation, Barrow Neurological Institute, Phoenix, AZ, United States

A 3D parallel imaging reconstruction technique is presented. This technique is a coil sensitivity based method used for reconstructing undersampled arbitrary 3D k-space trajectories. Iterations enforce receive b1-field and sampled data consistency without degridding/gridding operations improving the computational speed compared to similar reconstruction methods. The 3D trajectory used is Spiral Projection Imaging.

2895. Improvement of Quantitative MRI Using Radial GRAPPA in Conjunction with IR-TrueFISP

Martin Kunth1, Nicole Seiberlich2, Philipp Ehses1, Vikas Gulani2, Mark Griswold2

1Experimentelle Physik V, Universitaet Wuerzburg, Wuerzburg, Germany; 2Radiology, Case Western Reserve University, Cleveland, OH, United States

While the use of IR-TrueFISP to quantify the relaxation parameters T1 and T2 and the proton density M0 has been demonstrated, these values can be difficult to quantify in species with fast relaxation because the first points along the relaxation curve are hard to assess. This abstract explores the use of the recently proposed technique through-time radial GRAPPA to reconstruct highly undersampled radial images acquired along the relaxation curve. In this way, the first few points after the inversion can be assessed and the relaxation parameters more accurately quantified.

2896. Maxwell's Equation Tailored Reverse Method of Obtaining Coil Sensitivity for Parallel MRI

Jin Jin1, Feng Liu1, Yu Li1, Ewald Weber1, Stuart Crozier1

1ITEE, The University of Queensland, St Lucia, Queensland, Australia

A new method is proposed to obtain noise-free RF coil sensitivity maps. This is highly desirable, considering the fact that the sensitivity encoding (SENSE) method imposes ultimate dependence of successful full FOV image reconstruction on the correct sensitivity map of each individual coil. The proposed method differs from traditional methods in that, instead of refining the measured sensitivity maps by means of numerical approximation and/or extrapolation, it is based on physics of electromagnetics, parameterization and optimization algorithms. Preliminary simulations show substantial improvement in sensitivity maps constructed by proposed method compared to traditional polynomial fitting method and consequently in reconstructed images.

2897. Sub-Sampling Parallel MRI with Unipolar Matrix Decoding

Doron Kwiat1

1DK Computer College, Tel-Aviv, Israel

A method is proposed of parallel array scan, where signals from coils are combined by a summing multiplexer and decoded by unipolar matrix inversion is suggested, which reduces acquisition channels to a single pre-amp and A/D. The results would be, an independent individual separated signals as if acquired through multiple acquisition channels, and yet at a total acquisition time similar to acquisition time of multiple channels, Background In a standard parallel array technology, N coils simultaneously cover N FOVs by reading N k-space lines simultaneously over N independent data sampling channels. These k-space lines are phase weighted to maximize SNR and then FT converted to N independent images with an increased SNR[1]. In current accelerated PI techniques, some of K-space lines are skipped physically, and are replaced by virtual k-space substitutes using preumed spatial sensitivities of the coils in the PE direction [2-5]. Based on the method described recently [6,7] a new scanning procedure is described here. The Method 1.Have all coils be connected through a single summing multiplexer unit (MUX) which allows, at our discretion, selecting N-1 coils to be actively connected while a single coil is deactivated electronically, to a single summing common output (SCO). Let the summed signal from these N-1 coils be sampled by the single acquisition channel (ACQ) having a single pre-amp and single A/D. 2.Scan 1/Nth of the total k-space lines while having N-1 coils actively connected to the ACQ by the MUX unit. Repeat the above scan procedure over another 1/Nth part of k-space, this time with another set of N-1 coils actively connected, and 1 coil deactivated. Keep these scan procedures N times, until all k-space lines were acquired over all N possible permutations of selections of N-1 coils out of N. 3. There are now exactly N summed acquisitions at our hands. Using an inverse of a unipolar matrix, these can be now decoded back to the original individual k-space lines

Non-Cartesian Imaging Methods

Hall B Tuesday 13:30-15:30

2898. 3D Dual VENC PCMRA Using Spiral Projection Imaging

Nicholas Ryan Zwart1, James Grant Pipe1

1Keller Center for Imaging Innovation, Barrow Neurological Institute, Phoenix, AZ, United States

This work focuses on the reduction of scan time required by the phase-contrast MRA technique. The proposed method consists of a 3D variable density spiral projection imaging trajectory (SPI) combined with a dual velocity encoding technique. SPI is a rapid imaging technique that improves acquisition time through the intrinsic efficiency of spirals and through undersampling. The dual-VENC method improves SNR by allowing low-VENC (high SNR) data to be reconstructed without phase aliasing of the velocity measurements.

2899. Dynamic 3D Contrast Enhanced Liver Imaging Using a Novel Hybrid Cartesian-Radial Acquisition with Flexible Temporal and Spatial Resolution

Pascal Spincemaille1, Beatriu Reig1, Martin R. Prince1, Yi Wang1

1Radiology, Weill Cornell Medical College, New York, NY, United States

High temporal resolution dynamic contrast enhanced liver imaging is achieved using a novel k-space sampling method that samples the phase and slice encoding plane along true radial trajectories with an angularly varying field-of-view and resolution. Combined with an adapted golden ratio view order, it eliminates the need for accurate bolus timing and allows the retrospective selection of the optimal arterial enhancement for the detection and characterization of liver lesions.

2900. Magnetization-Prepared Shells with Integrated RadiaL and Spirals

Yunhong Shu1, Matt A. Bernstein1

1Department of Radiology, Mayo Clinic, Rochester, MN, United States

In this work, we demonstrate the initial feasibility of combining the SWIRLS trajectory with the MP-RAGE acquisition for volumetric T1-weighted brain imaging. The SWIRLS trajectory uses one continuous interleave to cover the surface of a spherical shell from pole-to-pole, which offer more flexibility for magnetization prepared (MP) design than the traditional shells trajectory. Meanwhile, it also shares the advantages of shells trajectory, including optimizing the contrast between WM and GM with reduced scan time.

2901. High-Field MRI for Non-Invasive Preclinical Imaging in Free-Breathing Mice

Prachi Pandit1,2, Yi Qi2, Kevin F. King3, G A. Johnson1,2

1Biomedical Engineering, Duke University, Durham, NC, United States; 2Center for In Vivo Microscopy, Duke University, Durham, NC, United States; 3GE Healthcare, Waukesha, WI, United States

The requirements for preclinical cancer imaging are high spatial resolution, good soft tissue differentiation, excellent motion immunity, and fast and non-invasive imaging to enable high-throughput, longitudinal studies. Here we describe a PROPELLER-based technique, which with its unique data acquisition and reconstruction overcomes the adverse effects of physiological motion, allows for rapid setup and acquisition and provides excellent tissue contrast. Hardware optimization as well as sequence modification enable us to obtain heavily T2-weighted images at high-fields in tumor-bearing mice with in-plane resolution of 117μm and slice thickness of 1mm. Multi-slice datasets covering the entire thorax and abdomen are acquired in ~40 minutes.

2902. ZOOM-PROPELLER-EPI: Non-Axial Imaging at Small FOV with PROPELLER-EPI

Hing-Chiu Chang1,2, Chun-Jung Juan3, Yi-Jui Liu4, Chao-Chun Lin2,5, Hao Shen6, Tzu-Chao Chuang7, Hsiao-Wen Chung2

1Applied Science Laboratory, GE Healthcare Taiwan, Taipei, Taiwan; 2Institute of Biomedical Electronics and Bioinformatics, National Taiwan University, Taipei, Taiwan; 3Department of Radiology, Tri-Service General Hospital, Taipei, Taiwan; 4Department of Automatic Control Engineering, Feng Chia University, Taichung, Taiwan; 5Department of Radiology, China Medical University Hospital, Taichung, Taiwan; 6Applied Science Laboratory, GE Healthcare, Beijing, China; 7Electrical Engineering, National Sun Yat-sen University, Kaohsiung, Taiwan

Current implementation of PROPELLER-EPI exhibits difficulty in small FOV or non-axial acquisition due to the aliasing artifact along the phase-encoding direction of each blade. In this work, we propose a ZOOM-PROPELLER-EPI technique, which combines the reducing-FOV (rFOV) EPI to obtain sagittal images with a small FOV. We combined PROPELLER-EPI with three types of rFOV EPI technique based on inner volume excitation, both phantom and in vivo results demonstrated effectiveness of ZOOM-PROPELLER-EPI. The proposed method may find applications in non-axial high-resolution scans such as diffusion-weighted imaging of the cerebellum.

Fat-Water Separation

Hall B Wednesday 13:30-15:30

2903. Quantification of Fatty Acid Compositions Using MR-Imaging and Spectroscopy at 3 T

Pernilla Peterson1, Håkan Brorson2, Sven Månsson1

1Medical Radiation Physics, Lund University, Malmö, Sweden; 2Plastic and Reconstructive Surgery, Lund University, Malmö, Sweden

This phantom study aims at investigating the potential of multi-echo imaging and spectroscopy to quantify the fraction unsaturated fatty acids (UF) and compare the results against known values. Six oil phantoms (UFs: 8%-92%) were measured in a 3T Siemens scanner with PRESS-localized spectroscopy and multi gradient echo sequences. Two fat resonances were separated from the acquired spectra using jMRUI and from multi-echo images using a linear least-squares approach. Both methods successfully quantified UFs with slopes/intercepts 0.886/3.80% and 0.956/11.3% for imaging and spectroscopy, respectively. This experiment successfully demonstrates the ability of multi-echo imaging and spectroscopy to evaluate fatty acid compositions.

2904. Bipolar 3D-FSE-IDEAL: Fast Acquisition of Volumetric T2-Weighted Fat and Water

Ananth J. Madhuranthakam1, Huanzhou Yu2, Ann Shimakawa2, Martin P. Smith3,4, Scott B. Reeder5, Neil M. Rofsky3,4, Charles A. McKenzie6, Jean H. Brittain7

1MR Applied Science Lab, GE Healthcare, Boston, MA, United States; 2MR Applied Science Lab, GE Healthcare, Menlo Park, CA, United States; 3Radiology, Beth Israel Deaconess Medical Center, Boston, MA, United States; 4Harvard Medical School, Boston, MA, United States; 5Radiology, Medical Physics, Biomedical Engineering and Medicine, University of Wisconsin, Madison, WI, United States; 6Medical Biophysics, University of Western Ontario, London, Ontario, Canada; 7MR Applied Science Lab, GE Healthcare, Madison, WI, United States

In this work, a bipolar acquisition with 3D-FSE-IDEAL is presented that reduces total scan time by acquiring all three images required for IDEAL processing in a single repetition. To eliminate phase errors that arise from alternating polarities of the readout gradients, a novel 2D phase correction method was implemented. High-resolution 3D T2-weighted images with uniform fat-water separation are demonstrated in breast and knee applications with less than 5-minute acquisition times.

2905. MR Water/Fat Separation Improves Optical Breast Imaging

Colin Morehouse Carpenter1, Shudong Jiang2, Brian William Pogue2, Keith David Paulsen2

1Radiation Oncology, Stanford University School of Medicine, Stanford, CA, United States; 2Thayer School of Engineering at Dartmouth, Hanover, NH, United States

IDEAL water/fat separation was used to improve hemoglobin quantification of MR-guided optical imaging. This technique is shown to reduce the cross-talk between oxyhemoglobin and water, caused by the spectral similarity of these tissue constituents in the near-infrared. It is demonstrated in gelatin phantoms that this approach reduces error in oxyhemoglobin by 70% on average for several cases. This finding has significant benefit for optical breast imaging, as the improved quantification provided by the MR water image can be leveraged to reduce the number of wavelengths in the optical data acquisition and thus increase temporal resolution.

2906. Flexible and Efficient Data Acquisition Technique for 3D-FSE-IDEAL

Ananth J. Madhuranthakam1, Huanzhou Yu2, Ann Shimakawa2, Martin P. Smith3,4, Scott B. Reeder5, Neil M. Rofsky3,4, Charles A. McKenzie6, Jean H. Brittain7

1MR Applied Science Lab, GE Healthcare, Boston, MA, United States; 2MR Applied Science Lab, GE Healthcare, Menlo Park, CA, United States; 3Radiology, Beth Israel Deaconess Medical Center, Boston, MA, United States; 4Harvard Medical School, Boston, MA, United States; 5Radiology, Medical Physics, Biomedical Engineering and Medicine, University of Wisconsin, Madison, WI, United States; 6Medical Biophysics, University of Western Ontario, London, Ontario, Canada; 7MR Applied Science Lab, GE Healthcare, Madison, WI, United States

FSE-IDEAL requires at least three echoes for uniform fat-water separation. The three echoes are commonly acquired in multiple repetitions. Recently, methods have been proposed to reduce total scan time by acquiring multiple gradient echoes in a repetition. Acquisition of a fourth echo increases the flexibility for choosing the gradient echo spacing to enable higher resolution acquisitions in reasonable scan times. We test this hypothesis in phantom studies and show a new data acquisition approach to acquire high-resolution 3D T2-weighted fat-water separated images of the breasts and knee with higher SNR in reduced scan times.

2907. Single-Image Water/fat Separation

Johan Berglund1, Håkan Ahlström1, Lars Johansson1, Joel Kullberg1

1Department of radiology, Uppsala university, Uppsala, Sweden

A post processing method is presented, that separates water and fat from a single complex image. Initially, each voxel is assumed to be either water- or fat dominant, giving two alternative field heterogeneity phasors. Spatial smoothness of the field map is imposed by formulating an optimization problem, which is solved approximately using a multiscale belief propagation algorithm. Smoothing of the field map relaxes the initial assumption of water- or fat dominance. Water and fat signals are found analytically in each voxel. Initial results from abdomen and whole-body datasets at 1.5 T and 3.0 T were found promising.

2908. Noise Analysis for Chemical Shift Based Water-Fat Separation with Independent T2* Correction for Water and Fat

Venkata Veerendranadh Chebrolu1, Huanzhou Yu2, Angel R. Pineda3, Charles A. McKenzie4, Jean H. Brittain5, Scott B. Reeder, 1,6

1Biomedical Engineering, University of Wisconsin Madison, Madison, WI, United States; 2Applied Science Laboratory, GE Healthcare,, Menlo Park,, CA, United States; 3Department of Mathematics, California State University, Fullerton, CA, United States; 4Department of Medical Biophysics, University of Western Ontario,, London, Ontario; 5Applied Science Laboratory, GE Healthcare,, Madison, WI, United States; 6Radiology, University of Wisconsin Madison, Madison, WI, United States

The noise analysis for chemical shift based decomposition of water and fat was theoretically computed for methods that account for single and dual exponential T2* correction along with spectral modeling of fat. The Cramer–Rao bound (CRB) formulation was used to study the variance of the estimates of the water and fat images by computing the maximum effective number of signals averaged (NSA) for a range of echo combinations and fat-water ratios. These theoretical results predict that noise performance degrades with independent estimation of T2* of water and fat.

2909. Lipid Suppresion Using Spectral Editing of Fast Spin Echo Trains

Andrew J. Wheaton1, James B. Murdoch1, Robert Anderson1

1Toshiba Medical Research Inst. USA, Mayfield, OH, United States

The REFUSAL [REFocusing Used to Selectively Attenuate Lipids] technique incorporates a spectrally-selective editing pulse in the position of the first refocus pulse of an rf echo train. By fully refocusing water and while minimally refocusing lipid resonances, fat signal is “refused” from evolving in the rf echo train. The phase-modulated REFUSAL pulse is designed for B1-robustness with a sharp transition between fat and water for good δB0-insensitivity. REFUSAL produces images with uniform, T1-insensitive fat suppression over a wide range of B1.

2910. PASTA++: B1- And T1-Robust Fat Suppression at 3T

Andrew J. Wheaton1, Robert Anderson1

1Toshiba Medical Research Inst. USA, Mayfield, OH, United States

PASTA uses a combination of low rf excitation bandwidth and alternate excitation and refocus slice selection gradient polarities to remove fat signal via chemical shift. PASTA++ is an improved version of PASTA designed for 3T. Using 3T-tailored rf pulse choices and irregular echo spacing, PASTA++ can be included in an fast spin-echo readout with short echo spacing. PASTA++ delivers high SNR images with uniform fat suppression even in the presence of B0 inhomogeneity. Since PASTA++ does not use a prepulse, it delivers fat suppression immune to B1- and T1-variation without increasing SAR.

2911. A Joint Estimation Method for Two-Point Water/fat Imaging with Regularized Field Map

Diego Hernando1, Peter Kellman2, Zhi-Pei Liang1

1Electrical and Computer Engineering, University of Illinois, Urbana, IL, United States; 2National Institutes of Health, Bethesda, MD, United States

Two-point methods for water/fat imaging are attractive because of their moderate acquisition time. In this work, we adapt a previously proposed joint estimation approach for two-point acquisitions and demonstrate its performance using simulations, phantom results and in vivo data. The proposed method, based on a regularized formulation and a graph cut solution, results in good noise properties and the ability to handle large B0 field inhomogeneities.

2912. Multiplex RARE Dixon: A Novel Multislice RARE Sequence Applied to Simultaneous Slice Fat-Water Dixon Imaging

Kuan J. Lee1, Benjamin Zahneisen1, Jürgen Hennig1, Weigel Matthias1, Jochen Leupold1

1Medical Physics, University Hospital Freiburg, Freiburg, Baden-Württemberg, Germany

Multiplex RARE is a new sequence in which multiple slices are simultaneously excited and refocused in a spin-echo train. The echo trains are interleaved in such a way that CPMG conditions are fulfilled at all times, and signals from slices can be separated, preventing aliasing. This work demonstrates how the sequence may be used in a novel fat-water Dixon method, which enables fast volume coverage of multiple, simultaneously excited slices. The technique is demonstrated in-vivo and compared with fTED, another fast Dixon method.

2913. Cardiac Imaging with Chemical Shift Based Water-Fat Separation at 3T

Karl Kristopher Vigen1, Chris J. Francois1, Ann Shimakawa2, Huanzhou Yu2, Scott K. Nagle1, Mark L. Schiebler1, Scott B. Reeder1,3

1Radiology, University of Wisconsin-Madison, Madison, WI, United States; 2Applied Science Lab, GE Healthcare, Menlo Park, CA, United States; 3Medical Physics, University of Wisconsin-Madison, Madison, WI, United States

Chemical shift based water-fat separation methods have recently been demonstrated for 1.5T cardiac imaging. Higher field strengths (most notably 3T) are increasingly used in cardiac imaging, but water-fat separation techniques can be challenging due to proportionately higher resonance frequency offsets. An interleaved multi-echo sequence using the IDEAL water-fat method has been developed for cardiac imaging at 3T and applied to the evaluation of delayed-enhancement imaging and other fat-containing pathologies.

2914. Feasibility of T2* Estimation with Chemical Shift-Based Water-Fat Separated Cardiac Imaging

Karl Kristopher Vigen1, Huanzhou Yu2, Chris J. Francois1, Ann Shimakawa2, Scott B. Reeder1,3

1Radiology, University of Wisconsin-Madison, Madison, WI, United States; 2Applied Science Lab, GE Healthcare, Menlo Park, CA, United States; 3Medical Physics, University of Wisconsin-Madison, Madison, WI, United States

T2* mapping has previously been investigated in cardiac imaging for iron overload assessment and detection of myocardial BOLD effects. Advanced T2* measurement techniques have been previously demonstrated with chemical shift-based fat-water separation techniques in applications such as iron- and fat-content measurement in the liver, and chemical shift-based fat-water decomposition methods have been used to separate fat and water in cardiac imaging. In this work, the feasibility of T2* mapping with chemical shift-based fat-water decomposition in cardiac imaging is demonstrated.

2915. Determination of Body Compartments at 1.5 and 3 Tesla, Combining Three Volume Estimation Methods

Tania Buehler1, Nicolas Ramseier1, Juergen Machann2, Nina Schwenzer2, Chris Boesch1

1Dept. of Clinical Research, University of Bern, Bern, Switzerland; 2Dept. of Diagnostic Radiology, Eberhard-Karls-University of Tübingen, Tübingen, Germany

Insulin resistance and the metabolic syndrome are cardiovascular risk factors with enormous consequences for the individual patient and the health care system. They can be linked with whole body fat (WBF), visceral adipose tissue (VAT), lean body volume (LBV), and whole body volume (WBV) imaged with MRI. In this study, a method is proposed and tested that uses point counting algorithms to determine the above mentioned body compartments in two groups of age-, weight-, height-, and BMI-matched volunteers at 1.5 and 3 Tesla.

2916. Autocalibrating Correction of Spatially Variant Eddy Currents for Three-Point Dixon Imaging

Holger Eggers1, Adri Duijndam2

1Philips Research, Hamburg, Germany; 2Philips Healthcare, Best, Netherlands

The use of bipolar readout gradients in three-point Dixon imaging increases scan efficiency and separation robustness, but eddy currents lead to phase variations that do not adhere to the assumed linear evolution over echo time. In first approximation, these phase variations are limited to one spatial direction and are easily removed prior to the separation. For large volumes, however, this approximation becomes inaccurate. A correction of these phase variations in all directions that requires no additional calibration data is proposed in this work and demonstrated to substantially improve the fat suppression over large volumes in three-point Dixon imaging.

2917. Three Echo Dixon Water-Fat Separation for Cardiac Black Blood Turbo Spin Echo Imaging

Peter Koken1, Holger Eggers1, Tobias Schaeffter2, Peter Börnert1

1Philips Research Europe, Hamburg, Germany; 2Divison of Imaging Sciences, King's College , London, United Kingdom

Turbo spin echo (TSE) sequences with black blood and fat suppression preparation pulses are widely used in cardiac MRI. In the presence of B0 inhomogeneity the common prepulse fat suppression techniques often fail. Furthermore, it was recently shown, that the amount and the distribution of fat in the heart could be of diagnostic value. We propose the combination of black blood TSE with a three echo GRASE-like readout and an iterative water fat separation reconstruction without restrictions to the inter echo time. Data were acquired ECG-triggered during breath-hold at both polarities of the readout gradient and combined with accelerated parallel imaging. The combination of TSE with the three point Dixon method could be an interesting new tool in cardiac MRI.

2918. Water Fat Separation with Undersampled TSE BLADE Based on Three Point Dixon

Qiang He1,2, Dehe Weng1,3, Xiaodong Zhou1,2, Marc Beckmann1, Cheng Ni1,2

1Siemens Mindit Magnetic Resonance Co. Ltd., Shenzhen, Guangdong, China; 2Life Science and Technology School, Tongji University, Shanghai, China; 3Beijing MRI Center for Brain Research, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China

By the method of integrating the total variation regularized iterative reconstruction and water fat separation calculation, the water and fat images with robust and high quality is reconstructed from the undersampled TSE BLADE three point Dixon with less scanning time comparing with full coverage of BLADE k-space trajectory. The final fat and water images have less streaking artifacts comparing with conventional regridding reconstruction methods followed by water-fat separation. Meanwhile, inheriting the benefits of the BLADE scanning, the present method is less sensitive to the motions comparing with Cartesian sampling.

2919. CS-Dixon: Compressed Sensing for Water-Fat Dixon Reconstruction

Mariya Doneva1, Peter Börnert2, Holger Eggers2, Alfred Mertins1, John Pauly3, Michael Lustig3,4

1Institute for Signal Processing, University of Lübeck, Lübeck, Germany; 2Philips Research Europe, Hamburg, Germany; 3Electrical Engineering, Stanford University, CA, United States; 4Electrical Engineering, UC Berkeley, CA, United States

An integrated Compressed Sensing-Dixon algorithm is proposed, which applies a sparsity constraint on the water and fat images and jointly estimates water, fat and field map images. The method allows scan time reduction of above 3 in 3D MRI, fully compensating for the additional time necessary to acquire the chemical shift encoded data.

2920. Accelerated Robust Fat/Water Separation at 7T

Sreenath Narayan1, Fangping Huang1, David Johnson2, Christoper Flask1,3, Guo-Qiang Zhang1, David Wilson1

1Case Western Reserve University, Cleveland, OH, United States; 2Ohio State University, Columbus, OH, United States; 3Unversity Hospitals, Cleveland, OH, United States

VARPRO-ICM was previously introduced as a Dixon processing formulation that was able to handle the very large field inhomogeneities seen at 7T. However, long processing times have prevented this formulation from achieving practical use. In this abstract, we present image processing improvements that decrease the processing times required to solve the VARPRO-ICM formulation by a factor of about 70.

2921. Consistent Region-Growing Based Dixon Water and Fat Separation for Images with Disconnected Objects

Hua Ai1, Jingfei Ma1

1The University of Texas M.D. Anderson Cancer Center, Houston, TX, United States

Consistent water and fat separation in images with disconnected objects is difficult for a region-growing based Dixon method. Here, we propose to monitor and record the quality index of a recently-proposed algorithm for region-growing at each step. The quality index is then used to automatically segment the disconnected objects into separate sub-images. Finally, the sub-images are consistently recombined on the basis of water and fat spectral asymmetry and slice-to-slice phase correlation. The proposed method was tested on a total of 1106 axial in vivo leg images and was shown to reduce the number of inconsistent slices from 203 to 6.

2922. Optimized Single-Acquisition Lipid- And Water-Selective Imaging at High Field

William M. Spees1, Tsang-Wei Tu1, Sheng-Kwei Song1, Joel Garbow1

1Biomedical MR Laboratory, Washington University School of Medicine, St. Louis, MO, United States

Side-lobe spatial-spectral excitation and frequency-selective saturation with a binomial-series RF pulse scheme were evaluated for application at high field. Both methods yield separate water- or lipid-selective images in a single acquisition. In most circumstances, the performance of the binomial saturation approach proves to be more robust. A strategy is described for overcoming unwanted artifacts arising from magnetic susceptibility mismatch in small-animal imaging.

2923. Chemical Shift Based Water-Fat Separation with an Undersampled Acquisition

Catherine J. Moran1, Ethan K. Brodsky, 12, Huanzhou Yu3, Scott B. Reeder, 12, Richard X. Kijowski2, Walter F. Block1,4

1Medical Physics, University of Wisconsin, Madison, WI, United States; 2Radiology, University of Wisconsin, Madison, WI, United States; 3Global Applied Sciences Lab, GE Healthcare, Menlo Park, CA, United States; 4Biomedical Engineering, University of Wisconsin, Madison, WI, United States

The chemical shift based IDEAL decomposition method generally requires redundant sampling at multiple time points. A unique undersampled radial k-space trajectory at each echo time provides a means to accelerate data acquisition while still allowing for robust chemical species decomposition. In this work we present a dual-pass dual-half-echo radial acquisition which utilizes undersampled source images with IDEAL to achieve bSSFP images with high isotropic resolution and robust fat-water separation in the breast and knee.

2924. Influence and Compensation of Fat Signal Dephasing and Decay in Two-Point Dixon Imaging

Holger Eggers1

1Philips Research, Hamburg, Germany

Fat has a complex spectral composition, which causes its signal to dephase and decay noticeably even over short intervals. The influence of these effects on the extent of fat suppression reached in two-point Dixon imaging is evaluated in this work and is found to strongly depend on the choice of echo times. Moreover, it is shown how more complex spectral models of fat may be incorporated into a generalized two-point Dixon method, with which a more uniform degree of fat suppression is achieved across a range of relevant echo times.

2925. Water Fat Separation with TSE BLADE Based on Three Points Dixon Technique

Dehe Weng1,2, Marc Beckmann1

1Siemens Mindit Magnetic Resonance Ltd, Shenzhen, Guangdong, China; 2Beijing MRI Center for Brain Research, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China

Three points Dixon method for water and fat separation based on TSE BLADE is proposed. New phase correction using the in-phase image blades is introduced for the reconstruction of the two out-of-phase images in order to keep the water fat chemical shift information so that the water and fat can be separated after the reconstruction. Result shows that water and fat can be separated correctly, furthermore, the method enjoys the advantage of blade, it's less vulnerable to rigid body motion and pulsation etc.

2926. Robust Field Map Estimation Using Both Global and Local Minimia

Hojin Kim1,2, Kyung Sung1, Brian Andrew Hargreaves1

1Department of Radiology, Stanford University, Stanford, CA, United States; 2Electrical Engineering, Stanford University, Stanford, CA, United States

In the least-squares fat/water separation techniques, the residual or cost runction that is minimized contains exactly one or two local minimum, depending on the relative amount of fat and water, and water-fat phase difference. Separation algorithms attempt to find which minimum provides true field-map, but may converge to the incorrect local minimum. Based on this principle, this work proposes a robust field-map estimation technique by tracking two minima at each pixel through region growing process and suggesting more secure way of determining an initial seed for region growing.

2927. Optimization of Flip Angle to Allow Tradeoffs in T1 Bias and SNR Performance for Fat Quantification

Catherine D. G. Hines1, Takeshi Yokoo2, Mark Bydder2, Claude B. Sirlin2, Scott B. Reeder1,3

1Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States; 2Radiology, University of California-San Diego, San Diego, CA, United States; 3Radiology, University of Wisconsin-Madison, Madison, WI, United States

Chemical shift based water-fat separation methods used to quantify fat in tissue are usually based on rapid 2D or 3D spoiled gradient echo methods. In order to avoid bias from differences in T1 between water and fat, a low flip angle is typically used to minimize this source bias. Reducing the flip angle reduces SNR performance, however. In this work, we present an algorithm to maximize the flip angle (to maximize SNR) while maintaining a user-defined allowable error in fat-fraction from T1 related bias. Experimental validation is also shown.

2928. Volumetric Adiposity Imaging Over the Entire Abdomen and Pelvis in a Single Breath-Hold Using IDEAL at 3.0T

Aziz Hatim Poonawalla1, Ann Shimakawa2, Huanzhou Yu2, Charles McKenzie3, Jean Brittain2, Scott Reeder1,4

1Radiology, University of Wisconsin, Madison, WI, United States; 2GE Healthcare, Waukesha, WI, United States; 3Medical Biophysics, University of Western Ontario, London, Ontario, Canada; 4Medical Physics, University of Wisconsin, Madison, WI, United States

We have demonstrated the capability to acquire high-spatial resolution 3D volumetric images of the entire abdomen and pelvis, using a highly-accelerated chemical-shift-based water-fat separation technique and a 32-channel coil at 3.0T. The high-quality fat and fat-fraction images obtained by this technique provide unprecedented visualization and delineation of the adipose depot boundaries, with sufficient spatial resolution to allow 3D reformatting for optimal segmentation. This new technique will greatly facilitate rapid quantitative assessment of visceral adipose tissue volume, VAT/SCAT ratio, and total adipose volume within a single-breath-hold acquisition without the need for ionizing radiation.

2929. Preliminary Results of IDEAL Fat/water Separation at 9.4T

Sébastien Bär1, Wilfried Reichardt1, Jochen Leupold1

1Dept. of Diagnostic Radiology, Medical Physics, University Hospital Freiburg, Freiburg, Germany

IDEAL has emerged as a promising mehtod for rapid fat/water separation. Here we present our first results on the feasibilty of this method on ex-vivo rat images at 9.4T.

Dynamic MR, Superresolution, Off-Resonance & Tissue Orientation

Hall B Thursday 13:30-15:30

2930. System Dynamics Estimation for Kalman Filtering with Radial Acquisition

Mahdi Salmani Rahimi1, Steve R. Kecskemeti2, Walter F. Block1,3, Orhan Unal3

1Biomedical Engineering, University of Wisconsin, Madison, WI, United States; 2Physics, University of Wisconsin, Madison, WI, United States; 3Medical Physics, University of Wisconsin, Madison, WI, United States

A novel method has been proposed to use adaptive Kalman filtering and causal DCF based tornado filtering together to reconstruct undersampled MR images for dynamic and time resolved applications. Existing Kalman method uses an initialization scan or a sliding window to estimate system dynamics. In this work, we used tornado filter to infer motion maps for the Kalman process. This helps us to have a better estimation of image changes at every time frame and therefore a more accurate reconstruction. Simulations have been done on a cardiac phantom using radial projections and results were compared to existing techniques.

2931. Deterministic Comparisons of Nonlinear Acceleration Methods Using a Realistic Digital Phantom

Leah Christine Henze1, Catherine J. Moran2, Matthew R. Smith2, Frederick Kelcz3, Dan Xu4, Kevin F. King4, Alexey Samsonov3, Walter F. Block, 12

1Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, United States; 2Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, United States; 3Department of Radiology, University of Wisconsin-Madison, Madison, WI, United States; 4Global Applied Science Lab, General Electric Healthcare, Milwaukee, WI, United States

Several different accelerated imaging methods exist that can improve the acquisition of dynamic data. Clinical adoption of many of these methods has been slow, partially due to the difficulty in conclusively proving the extent to which a specific method provides additional diagnostic information that would not otherwise have been available. We have created a realistic digital phantom from which k-space data for a DCE exam can be simulated and reconstructed by both Cartesian and non Cartesian acceleration methods. We use the phantom to quantitatively analyze and compare the performance of multiple accelerated imaging methods.

2932. Subtraction in View-Shared 3D Contrast-Enhanced MRA

Eric Allen Borisch1, Clifton R. Haider1, Roger C. Grimm1, Stephen J. Riederer1

1Radiology, Mayo Clinic, Rochester, MN, United States

3D contrast-enhanced MR Angiography frequently uses a pre-contrast (tissue) acquisition as a subtraction reference (mask) to improve the output image quality and contrast-to-noise ratio. We discuss the appropriate application of this technique to the case of 3D time-resolved view-shared reconstructions, including at what stage in the reconstruction process the subtraction is performed and the selection of effective mask data to suppress magnetization history effects.

2933. On Temporal Filtering Effects Caused by the Subtraction of Temporal Average in Dynamic Parallel MRI

Irene Paola Ponce1, Martin Blaimer2, Felix Breuer2, Peter Michael Jakob1,2, Mark A. Griswold3, Peter Kellman4

1Experimental Physics 5, University of Würzburg, Würzburg, Bavaria, Germany; 2Research Center Magnetic Resonance Bavaria (MRB), Würzburg, Bavaria, Germany; 3Department of Radiology, University Hospitals of Cleveland and Case Western Reserve University, Cleveland, OH, United States; 4Laboratory of Cardiac Energetics, National Institutes of Health, National Heart, Lung and Blood Institute, Bethesda, MD, United States

Many of Parallel MRI techniques are based on a time-interleaved acquisition scheme and allow dynamic imaging with high frame rates. In addition, in order to improve the SNR, the temporal average (also referred to as direct current, DC) is subtracted from the raw data so that only the dynamics of the object is reconstructed. In this work we demonstrate that DC subtraction may lead to temporal filtering effects in form of signal nulls in the temporal frequency spectra of the reconstructed images. We propose to correct the DC by an additional GRAPPA reconstruction prior to subtraction from the raw data.

2934. A Dynamic-Phase Extension for Model-Based Reconstruction of Breast Tumor Dynamic Contrast Enhanced MRI

Benjamin K. Felsted1, Ross T. Whitaker1, Matthias C. Schabel2, Edward V.R. DiBella2

1School of Computing, University of Utah, Salt Lake City, UT, United States; 2Department of Radiology, University of Utah, Salt Lake City, UT, United States

Introduction: We extend the model-based reconstruction method with a physically based linear-phase model that can account for gadolinium field distortions. Methods: Both constant- and linear-phase models were used in reconstructing two 4D breast DCE k-space acquisitions, retrospectively undersampled at R-factors of 1, 4, and 8. Results: Image reconstruction errors correlate spatially with dynamic image phase estimation errors. The errors of the constant-phase model grow fastest as R increases. Conclusion: The new extension can reduce most of the error from phase. The reconstructions have full spatial resolution without the blurring, ghosting, and ringing spatial artifacts typically associated with aggressive undersampling.

2935. Estimation of Superresolution Performance

Gerrit Schultz1, Maxim Zaitsev1

1Diagnostic Radiology - Medical Physics, University Hospital Freiburg, Freiburg, Germany

In this contribution a method for the estimation of Superresolution performance is presented. For adequately designed reconstruction methods, the modulations of the rf coil sensitivities can be used to extend the acquired gradient-encoded k-space region. This extension directly results in a resolution improvement. The k-space representation of the sensitivity maps gives a global estimate about the degree of this k-space extension. Resolution is investigated by performing a point spread function analysis. Simulated data are presented and verified with measurement results based on a standard 2D-CSI sequence.

2936. FREBAS Domain Super-Resolution Reconstruction of MR Images

Satoshi Ito1, Yoshifumi Yamada1

1Research Division of Intelligence and Information Sciences, Utsunomiya University, Utsunomiya, Tochigi, Japan

Super-resolution is a method of generating images beyond the limit of the resolution. Recently, a method by which to realize super-resolution by a technique that performs registration by a sub-pixel unit from several pieces of an image has been reported. Gerchberg-Papoulis (GP) method is known to realize super-resolution from a single image and signal, however, spatial resolution will not be improved well when it is based on the Fourier transform. On the other hand, GP method involving convolution integral can expand the signal band easily and the resultant image has higher resolution. In this study, we investigated the super-resolution of images using FREBAS transform that can be considered as a kind of multi-resolution image analysis based on convolution integral. Improvement of resolution on the image space with reference to the scaling parameter of FREBAS transform is examined.

2937. Seed Localization in MRI-Guided Prostate Brachytherapy Using Inversion-Recovery with ON-Resonant Water Suppression (IRON)

Nathanael Kuo1, Junghoon Lee1, Clare Tempany2, Matthias Stuber1, Jerry Prince1

1Johns Hopkins University, Baltimore, MD, United States; 2Brigham and Women's Hospital, Boston, MA, United States

An MRI pulse sequence and a corresponding image processing algorithm to localize prostate brachytherapy seeds during or after therapy are presented. Inversion-Recovery with ON-resonant water suppression (IRON) is an MRI methodology that generates positive contrast in regions of magnetic field susceptibility, as created by brachytherapy seeds. Phantoms comprising of several materials found in seeds were created to assess the usability of IRON for imaging seeds. Resulting images show that seed materials are clearly visible with high contrast using IRON. A seed localization algorithm to process IRON images demonstrates the potential of this imaging technique for seed localization and dosimetry.

2938. A Positive Contrast Method for MR-Lymphography Using Superparamagnetic Iron Oxide Nanoparticles

Haitao Zhu1, Kazuyuki Demachi1

1Department of Nuclear Engineering, The University of Tokyo, Tokyo, Japan

The objective of this work is to apply a post-processing method in MR-lymphography with superparamagnetic iron oxide nanoparticle (SPION) enhancement to achieve positive contrast in the image. The method analyzes the echo position shift caused by susceptibility gradient and uses this criterion to enhance region with large gradient caused by SPIONs. Both phantom and animal experiments are performed to test the method. Results show that this positive contrast method can generate enhanced signal at the region targeted by SPIONs and might provide additional information in MR-lymphography.

2939. Reconstruction Method for Non-Homogeneous Magnetic Fields Using the Fractional Fourier Transform

Vicente Parot1,2, Carlos Sing-Long1,2, Carlos Lizama3, Sergio Uribe, 2,4, Cristian Tejos1,2, Pablo Irarrazaval1,2

1Department of Electrical Engineering, Pontificia Universidad Catolica de Chile, Santiago, Chile; 2Biomedical Imaging Center, Pontificia Universidad Catolica de Chile, Santiago, Chile; 3Department of Mathematics and Computer Science, Universidad de Santiago de Chile, Santiago, Chile; 4Department of Radiology, Pontificia Universidad Catolica de Chile, Santiago, Chile

In Magnetic Resonance Imaging (MRI) field inhomogeneities produce severe distortions, especially with long acquisition sequences, e.g. EPI. Shimming or post-processing strategies are usually applied to correct those distortions. However, those approaches require additional hardware or long processing times. We propose an alternative reconstruction method based on the Fractional Fourier Transform (FrFT) assuming spatially-varying quadratic fields. We tested our method in phantoms and in vivo acquisitions. Results demonstrate the ability of our reconstruction scheme to correct the geometric distortions that appear in standard Fourier Transform reconstructions under non homogeneous fields.

2940. Geometrically Accurate Positive Contrast of Field Disturbances Using RAdial Sampling with Off-Resonance Reconstruction (RASOR).

Hendrik de Leeuw1, Peter R. Seevinck1, Clemens Bos2, Gerrit H. van de Maat1, Chris J.G. Bakker1

1Image Sciences Institute, Utrecht, Netherlands; 2Philips healthcare

With the advent of short-TE acquisitions, such as UTE and SWIFT, center out radial acquisition schemes to fill k-space are gaining interest. Although these short TE acquisitions minimize signal dephasing, they still suffer from field inhomogeneities in terms of geometric distortion. Still geometrically accurate depiction and localization of local field disturbers can be achieved by a 3D center-out radial acquisition by using off-resonance acquisition or reconstruction (RASOR). The advantage of RASOR reconstruction is a more precise determination of shape and location of the field disturbance, while retaining the original image.

2941. Spiral Off-Resonance Distortion Correction for Tagged MRI Using Spectral Peak Matching and HARP Refinement

Harsh K. Agarwal1, Xiaofeng Liu1, Khaled Z. Abd-Elmoniem2, Jerry L. Prince1

1Department of Electrical and Computer Engineering, The Johns Hopkins University, Baltimore, MD, United States; 2National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, United States

Off-resonance due to magnetic field inhomogeneity causes geometric distortion in tagged images acquired using a segmented spiral k-space data acquisition. This causes erroneous alignment of horizontal and vertical tag acquisitions and inaccurate displacement estimation. A technique based on fast marching HARP refinement is proposed to estimate and correct for the distortion. Improved motion estimation is demonstrated on an in vivo data set.

2942. Multi-GPU Implementation for Iterative MR Image Reconstruction with Field Correction

Yue Zhuo1, Xiao-Long Wu2, Justin P. Haldar2, Wen-mei W. Hwu2, Zhi-Pei Liang2, Bradley P. Sutton1

1Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, United States; 2Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, United States

Nowadays Graphics Processing Units (GPU) leads high computation performance in science and engineering application. We propose a multi-GPU implementation for iterative MR image reconstruction with magnetic field inhomogeneity compensation. The imaging model includes the physics of field inhomogeneity map and its gradients, and thus can compensate for both geometric distortion and signal loss. The iterative reconstruction algorithm is realized on C-language based on Compute Unified Device Architecture (CUDA). Result shows the performance of multi-GPU gains significant speedup by two orders of magnitude. Therefore, the fast implementation make the clinical and cognitive science requirements are achievable for accurate MRI reconstruction.

2943. Fiber Orientation Dependance of T2* Relaxation Time in the Whole Human Brain at 3T

Benjamin Bender1, Uwe Klose1

1University Hospital Tübingen, Department of Diagnostic and Interventional Neuroradiology, Tübingen, Germany

Recent publications suggest a relationship between white matter fiber orientation and T2* contrast at higher field strengths. In this study the relationship between fiber orientation and B0 for normal and tilted head position was examined in the whole human brain at 3T. As previously shown by Wiggins et al. for the cingulum and corpus callosum, WM signal intensity in the whole brain changed when the head was tilted. Blood vessels following the fiber tracts could explain the relationship found between B0 and relaxation rate, while a magic angle effect cannot explain the measured relationship.

2944. Sensitivity of MRI Resonance Frequency to the Orientation of Brain Tissue Microstructure

Jongho Lee1, Karin Shmueli1, Masaki Fukunaga1, Peter van Gelderen1, Hellmut Merkle1, Afonso C. Silva2, Jeff H. Duyn1

1Advanced MRI/LFMI/NINDS, National Institutes of Health, Bethesda, MD, United States; 2CMU/LFMI/NINDS, National Institutes of Health, Bethesda, MD, United States

Here we demonstrate microstructural orientation affects the MRI resonance frequency. The experiment was designed to avoid macroscopic susceptibility effect to identify true microstructural effect. We suggest an origin related to anisotropic susceptibility.

Relaxometry

Hall B Monday 14:00-16:00

2945. Wide-Range T1 Mapping Using Two Variable Flip Angle Acquisitions

Rahul Sarkar1, Alan R. Moody1,2, James Q. Zhan2, General Leung1,2

1Medical Biophysics, University of Toronto, Toronto, Ontario, Canada; 2Medical Imaging, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada

Variable flip angle (VFA) methods using two optimized flip angles have become popular for in-vivo T1 mapping within a limited range of a specific T1 of interest. The range limitation in this approach is generally due to bias against long T1s in the signal-dynamic range product used for flip angle optimization. This study presents a new strategy for flip angle pair selection that mitigates this bias to provide highly uniform accuracy and precision across the biological T1 range. In using only two flip angle acquisitions, this method represents a rapid approach to wide-range VFA T1 mapping.

2946. Fast T1 Mapping of Mouse Brain at 7 T with Time-Optimized Partial Inversion Recovery Utilizing a Surface Coil

Naoharu Kobayashi1, Hironaka Igarashi1, Tsutomu Nakada1

1Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Niigata, Japan

We present a new method for measuring a longitudinal relaxation time, T1, for a surface coil application utilizing adiabatic saturation pulses, referred to here as time-optimized partial inversion recovery (TOPIR). The recovery delays before and after the inversion pulse were optimized to sample data points such that the total sequence time was minimized under a specified dynamic range of the recovery curve. Accuracy of the method was validated by comparing the values obtained utilizing conventional inversion recovery sequence. The method enabled a two dimensional T1 mapping of a mouse brain using a 6 point recovery curve in 20–36 s.

2947. The Effect of Heart Rate in Look-Locker Cardiac T1 Mapping

Glenn S. Slavin1, Ting Song1, Jeffrey A. Stainsby2

1Applied Science Laboratory, GE Healthcare, Bethesda, MD, United States; 2Applied Science Laboratory, GE Healthcare, Toronto, ON, Canada

Because inversion times in cardiac Look-Locker acquisitions are a function of heart rate, T1 measurements can be incorrect. Pulse sequence modifications to account for heart rate variability and its effect on the magnetization recovery curve can significantly improve T1 accuracy.

2948. Demonstrating the Influence of Magnetisation Transfer on Putative T1 Relaxation Times: A Simulation Study

Miriam Rabea Kubach1, Kaveh Vahedipour2, Ana Maria Oros-Peusquens2, Tony Stoecker2, N. Jon Shah2,3

1Institute of Neuroscience and Medicine , Forschungszentrum Juelich, Juelich, Germany; 2Institute of Neuroscience and Medicine, Forschungszentrum Juelich, Juelich, Germany; 3Faculty of Medicine, Department of Neurology, , RWTH Aachen University, JARA,, Aachen, Germany

T1 is an MRI parameter very sensitive to pathological changes. Proper T1-mapping is therefore vital for many MRI applications, but the variability of T1 values within different methods is larger than within a group of volunteers measured with the same method. The accuracy of the T1 determination is affected by a number of rectifiable parameters but also influenced by MT in ways, which are strongly method-dependent and usually not quantified. We present numerical simulations, based on an existing software package JEMRIS, which allow one to simulate MR sequences considering MT effects. We investigate changes in the T1 relaxation of the observable water component due to the presence of and exchange with a bound proton pool. A simple pulse-acquire sequence is used for simulations, which can be the elementary building block of more realistic MR imaging sequences.

2949. Fast T1/B1 Mapping Using Multiple Dual TR RF-Spoiled Steady-State Gradient-Echo Sequences

Tobias Voigt1, Stefanie Remmele2, Ulrich Katscher2, Olaf Doessel1

1Institute of Biomedical Engineering, University of Karlsruhe, Karlsruhe, Germany; 2Philips Research Europe, Hamburg, Germany

Efficient and accurate baseline T1 and B1 quantification is a pre-requisite for standardized and clinical Dynamic Contrast-Enhanced MRI (DCE-MRI). This study investigates a new approach called “Multiple TR B1/T1 Mapping” (MTM), capable of fast, simultaneous B1 and T1 mapping. In this work, MTM is analysed with respect to its T1 mapping performance in comparison with an inversion recovery reference sequence and in due consideration of the limited time allowed in a clinical set-up. In calibrated phantom measurements, MTM T1 mapping was found to be more accurate than IR-TSE, inter alia due to its intrinsic B1 correction mechanism.

2950. Fast T1 Mapping at 7T Using Look-Locker TFEPI

Emma Louise Hall1, Ali M. Al-Radaideh1, Su Y. Lim2, Susan T. Francis1, Penny A. Gowland1

1Sir Peter Mansfield Magnetic Resonance Centre, University of Nottingham, Nottingham, Nottinghamshire, United Kingdom; 2Clinical Neurology, University of Nottingham, Nottingham, Nottinghamshire, United Kingdom

Ultra high field has the benefit of increased SNR to facilitate high resolution imaging. However, the lengthened relaxation time requires long scan times to produce high resolution T1 maps due to the need to allow the system to return to equilibrium. Here we present a Look-Locker TFEPI sequence that allows the acquisition of high resolution, 1.25mm isotropic, T1 maps with large volume coverage at 7T in less than 6 minutes.

2951. Accelerated Mapping of T1 Relaxation Times Using TAPIR

Klaus Möllenhoff1, N Jon Shah1,2, Eberhard D. Pracht1, Tony Stöcker1

1Institute of Neuroscience and Medicine – 4, Medical Imaging Physics, Forschungszentrum Juelich GmbH, Juelich, Germany; 2Faculty of Medicine, Department of Neurology, RWTH Aachen University, JARA, Aachen, Germany

TAPIR is an extremely flexible Look-Locker sequence that allows choices to be made regarding coverage and number of time points acquired on the recovery curve. We are using AFP inversion pulses to be more accurate and a segmented EPI readout together with parallel imaging to reduce the total acquisition time.

2952. Rapid 3D Relaxation Time and Proton Density Quantification Using a Modified Radial IR TrueFisp Sequence

Philipp Ehses1, Vikas Gulani2, Peter Michael Jakob1, Mark A. Griswold2, Felix A. Breuer3

1Dept. of Experimental Physics 5, Universität Würzburg, Würzburg, Germany; 2Department of Radiology, Case Western Reserve University and University Hospitals of Cleveland, Cleveland, OH, United States; 3Research Center Magnetic Resonance Bavaria (MRB),, Würzburg, Germany

The IR TrueFISP sequence has been shown to be a promising approach for the simultaneous quantification of proton density, T1 and T2 maps. However, delays between individual segments are required in order to allow the magnetization to recover, resulting in relatively long scan times. Recently, a modified IR TrueFISP method has been proposed, which does not necessitate relaxation delays. This method was combined with a radial stack-of-stars acquisition with golden-ratio based profile order, in order to rapidly obtain a full set of parameter maps of the brain in three dimensions.

2953. The Influence of Finite Long Pulse Correction on DESPOT2

Hendrikus Joseph Alphons Crooijmans1, Klaus Scheffler1, Oliver Bieri1

1Division of Radiological Physics, Department of Medical Radiology, University of Basel Hospital, Basel, Switzerland

The DESPOT2 theory is based on the assumption of instantaneous RF pulses. However, this is a pure theoretical assumption and it can never be met in practice, only approached with short pulse durations. Explicitly in cases where MT effect reduction is desired, long RF pulses are applied and the assumption is not met leading to deviation of calculated T2 from true T2 values. The implementation of a correction for finite pulse effects in the DESPOT2 theory makes the method independent of RF pulse duration and marginal deviations of around 1% of the true T2 are obtained for the calculated T2.

2954. Quantification of Transversal Relaxation Time T2 Using an Iterative Regularized Parallel Imaging Reconstruction

Markus Kraiger1, Florian Knoll1, Christian Clason2, Rudolf Stollberger1

1Institute of Medical Engineering, Graz University of Technology, Graz, Austria; 2Institute for Mathematics and Scientific Computing, University of Graz, Graz, Austria

Nonlinear parallel imaging reconstruction using an iterative regularized Gauss Newton method has shown its potential in several applications. This technique determines both the coil sensitivities and the image from undersampled multi-coil data. It enables high acceleration factors without pronounced local enhancement of noise. The numerical implementation of this sophisticated method requires data normalization steps which are usually performed individually for each slice and echo. In this study it was investigated if this type of reconstruction is applicable for quantitative imaging despite the complex reconstruction including image individual normalization. For that purpose high resolution multi-echo imaging with different acceleration factors was used for the quantification of the transverse relaxation time (T2).

2955. In-Vivo and Numerical Studies of Myelin Water Fraction in Rat Spinal Cord

Kevin D. Harkins1,2, Adrienne N. Dula1,2, Mark D. Does, 1,3

1Institute of Image Science, Vanderbilt University, Nashville, TN, United States; 2Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, United States; 3Biomedical Engineering, Vanderbilt University, Nashville, TN, United States

The myelin water fraction (MWF) estimated from multi-exponential T2 analysis is an effective marker of myelin in tissue, but there is evidence that the MWF is underestimated due to the exchange of water between myelin and other tissue compartments. In this work, in-vivo experiments confirm a bias in the MWF within rat spinal cord. Numerical studies further suggest that exchange can account for the variation in MWF, and that exchange between T2 components may be limited by the apparent diffusivity of myelin water.

2956. Evaluation of a Fast T2 Mapping Method in the Brain

Julien Sénégas1, Stefanie Remmele1, Wei Liu2

1Philips Research Europe, Hamburg, Germany; 2Philips Research North America, Briarcliff, NY, United States

T2 measurements provide important information about the mobility and chemical environment of water in the tissue of interest. The most frequent method for accurate T2 quantification uses multi-echo spin-echo (MESE incorporating multiple refocusing pulses in each repetition time following the CPMG sequence. To cover a wide range of T2 values, the number of spin echoes and corresponding RF pulses needs to be relatively large, resulting in increased TR, long scan durations, and a high SAR. Recently, a fast T2 mapping method, reducing the total number of phase encoding steps of a MESE sequence without sacrificing spatial resolution nor the dynamic range of T2 values, was proposed and evaluated in simulations and pre-clinical experiments. In this work, the accuracy of this acceleration technique for T2 mapping in the human brain was assessed in a larger group of volunteers.

2957. T1 Corrected Fast T2 Mapping Using Partially Spoiled SSFP

Oliver Bieri1, Klaus Scheffler1, Carl Ganter2

1Radiological Physics, University of Basel Hospital, Basel, Switzerland; 2Department of Diagnostic Radiology, Technical University Munich, Munich, Germany

Only recently a fast method for quantitative T2 mapping was introduced based on partially RF spoiled SSFP sequences (T2-pSSFP). It has been shown that for large flip angles, estimation of T2 is independent on T1 but becomes sensitive for low to moderate excitation angles. We will show that a correction of T2-pSSFP with T1 is possible and yields accurate T2 values for flip angles down to 30°. This offers the possibility for acquisitions with higher SNR, but requires prior knowledge of T1.

2958. Free Breathing Myocardial T2 Measurements

Maelene Lohezic1,2, Anne Menini2,3, Brice Fernandez1,2, Damien Mandry, 2,4, Pierre-Andre Vuissoz2,3, Jacques Felblinger2,3

1Global Applied Science Lab., GE Healthcare, Nancy, France; 2IADI, Nancy-Université, Nancy, France; 3U947, INSERM, Nancy, France; 4CHU Nancy, Nancy, France

Myocardial T2 measurements usually require multiple breath hold acquisitions, leading to patient discomfort and misregistrations between images. We present a new method allowing free breathing T2 quantification that combines respiratory motion estimation, motion compensated reconstruction and T2 calculation. It has been validated on five healthy volunteers and has shown no significant difference compared to the standard breath hold technique. A morphological proton density weighted image is also obtained, allowing accurate examination of heart structures. Such technique could be used for cardiac iron overload assessment or detection of early rejection of heart transplant, even in non cooperative patients such as children.

2959. Temporal Phase Correction of Quantitative T2 Data

Thorarin A. Bjarnason1, Cheryl R. McCreary1, Jeff F. Dunn1, J Ross Mitchell1

1University of Calgary, Calgary, AB, Canada

Magnetic resonance images are formed typically by taking the magnitude of reconstructed complex values. The magnitude operation changes the noise distribution from Gaussian to Rician. This operation causes artifacts in T2 distributions calculated using the non-negative least squares algorithm. The artifacts caused by non-Gaussian noise distributions are becoming more relevant as scientists begin to identify tissue compartments with small intensity long T2 decays. Here we propose, and examine, a temporal phase correction method allowing T2 distributions to be created from complex quantitative T2 data.

2960. T2 Mapping Using T2prepared-SSFP: Optimizing Echo Time, Flip Angle and Parameter Fitting

Shivraman Giri1, YiuCho Chung2, Saurabh Shah2, Hui Xue3, Jens Guehring3, Sven Zuehlsdorff2, Orlando P. Simonetti

1The Ohio State University, Columbus, OH, United States; 2Siemens Healthcare; 3Siemens Corporate Research

In this study, we analyze the effect of flip angles and choice of T2Prep times in T2 quantification using Magnetization prepared balanced SSFP sequence.

2961. Making High Resolution T2 and T2* Maps Through the Use of Accelerated Gradient-Echo Asymmetric Spin-Echo (GREASE) Pulse Sequences

Daniel Lee Shefchik1, Andrew Scott Nencka1, Andrzej Jesmanowicz1, James S. Hyde1

1Biophysics, Medical College of Wisconsin, Milwaukee, WI, United States

The gradient-echo asymmetric spin-echo pulse sequence (GREASE) allows for the production of T2 and T2* maps. In order to obtain high resolution maps, while maintaining signal, the GREASE sequence was modified to accelerate the acquisition of the images three different ways. The modifications included partial k-space GREASE [2], generalized autocalibrating partially parallel acquisitions (GRAPPA) Grease [3], and partial k-space GRAPPA GREASE. The sequences are implemented and compared to the original GREASE sequence to determine the best technique to obtain quality T2 and T2* maps.

2962. R2/R2* Estimation Errors in Combined Gradient- And Spin-Echo EPI Sequences Due to Slice-Profile Differences Between RF Pulses

Heiko Schmiedeskamp1, Matus Straka1, Roland Bammer1

1Lucas Center, Department of Radiology, Stanford University, Stanford, CA, United States

There is an increased interest in combined gradient-echo and spin-echo pulse sequences for applications in PWI and fMRI, facilitated by the differences in signal decay of gradient echoes and spin echoes depending on the mean vessel size within a voxel. This abstract deals with issues of mismatched slice profiles in such pulse sequences between the 90° excitation pulse and the 180° refocusing pulse, and it introduces a scaling factor for improved T1-independent R2 and R2* quantification.

2963. Multi Echo Spiral Imaging : Optimized K-Space Trajectories for T2* Quantification.

Nicolas Pannetier1,2, Mohamed Tachrount1,2, Christoph Segebarth1,2, Emmanuel Louis Barbier1,2, Laurent Lamalle3

1Inserm, U836, Grenoble, France; 2Université Joseph Fourier, Grenoble Institut des Neurosciences, UMR-S836, Grenoble, France; 3IFR n°1, INSERM, Grenoble, France

Effective and theoretical k-space trajectories differ due to eddy currents or gradient hardware imperfections. In this study we propose a fast two steps approach to optimized k-space trajectories in multi-echo spiral imaging. Once optimized, images were acquired on rat brain and T2* map was estimated.

2964. T2* Mapping at 7 T

Kai Zhong1, Ralf Deichmann2, Weiqiang Dou1, Oliver Speck1

1Biomedical Magnetic Resonance, Otto-von-Guericke University, Magdeburg, Saxon-Anhalt, Germany; 2Brain Imaging Center, University Frankfurt, Frankfurt, Germany

Previous studies at 7 T have related T2* maps to the iron deposition in brain tissue. However, the field inhomogeneity and susceptibility distortion at 7 T are significantly higher compared to lower field. This potentially distorts the true T2* values and could lead to false estimation of the tissue iron content. In this study, T2* correction based on the susceptibility gradients was applied to 7 T and can improve the resulting T2* maps. This method therefore should help to improve the accurate determination of T2* at 7 T for clinical studies. On the other hand, stronger dephasing is encountered, so thinner slices should be chosen than at lower fields to avoid systematic errors.

2965. R2* Reference Phantoms for Longitudinal Research Studies

Matthew T. Latourette1, James E. Siebert1

1Radiology, Michigan State University, East Lansing, MI, United States

In longitudinal research studies that employ R2*/T2* quantitation, reference phantoms can serve to improve the sensitivity and reproducibility of R2* measurements through detection and correction of bias and reduction of the variance of pooled study data. Stable phantoms comprised of agarose and carageenan gel doped with SPIO, NiCl2, and methylisothiazolinone were developed, enabling reliable R2* measurements that are adequately insensitive to temperature variations near room temperature. The phantoms’ R2* dependence on B0 was evaluated at field strengths of 0.35T, 0.7T, 1.5T, 3.0T. Chemical stability has been evaluated since phantom construction in April 2009.

2966. Transverse Relaxation of Water in Ferritin Gel: Relative Contributions of Iron and Gel

Nobuhiro Takaya1, Hidehiro Watanabe1, Fumiyuki Mitsumori1

1National Institute for Environmental Studies, Tsukuba, Ibaraki, Japan

Transverse relaxation of tissue water in human brain was explained with a linear combination of contributions from ferritin iron and the macromolecular mass fraction defined as 1-water fraction. This work examined whether the same scheme is applicable to relaxation of a model system composed of ferritin and agarose gel. The result of multiple regression analysis on the system showed that transverse relaxation in the system was described in the same manner as in human brain. B0 dependence of R2 demonstrated that the relaxation mechanism due to iron in gel samples is identical to that reported for a ferritin solution.

2967. Water-Specific Quantitative MRI Relaxometry of the Brain Using Spatial-Spectral Water Excitation: Preliminary Experience

Stephan William Anderson1, Jorge A. Soto1, Osamu Sakai1, Hernan Jara1

1Radiology, Boston University Medical Center, Boston, MA, United States

The purpose of this work was to test a pulse sequence for spatial- and spectral-selective qMRI relaxometry in vivo for deriving qMRI parameters in brain imaging. The brain of a volunteer was imaged using both non-chemically selective mixed-TSE sequence as well as the SSE-mixed-TSE pulse sequence to derive parametric maps of PD, T1, T2 (including secular-T2), and ADC of the brain. T2 was found to be consistently longer for the SSE-mixed-TSE pulse sequence. Spectrally selective qMRI may offer insight into both normal structures as well as pathology without the confounding effects of lipids.

2968. Simultaneous T1 and T2 Mappings Using Partially Spoiled Steady State Free Precession (PSSFP)

Paulo Loureiro de Sousa1,2, Alexandre Vignaud3, Laurie Cabrol1,2, Pierre G. Carlier1,2

1Institut de Myologie, Laboratoire de RMN, Paris, France; 2CEA, I2BM, Paris, France; 3Siemens Healthcare, Saint Denis, France

A fast 3D T2 mapping technique based on two partially Spoiled Steady State Free Precession (pSSFP) acquisitions has recently been presented. For most human soft tissues, accurate T2 measurements can only be obtained for high flip angle (FA) leading to SAR issues especially at high field. In this work we proposed an analytical expression derived from pSSFP theory which allowed us to introduce a more flexible T2 mapping technique. By doubling data collection, T1 map can also be extracted. The method has been validated on a phantom comparing pSSFP results with standard T1 and T2 measurements.

2969. Single-Shot Proton Density, T1 and T2 Quantification with Radial IR TrueFISP: Effect of Magnetization Transfer and Long RF Pulses

Philipp Ehses1,2, Vikas Gulani3, Stephen Yutzy3, Nicole Seiberlich3, Peter Michael Jakob1,2, Mark A. Griswold3

1Dept. of Experimental Physics 5, Universität Würzburg, Würzburg, Germany; 2Research Center Magnetic Resonance Bavaria (MRB), , Würzburg, Germany; 3Department of Radiology, Case Western Reserve University and University Hospitals of Cleveland, Cleveland, OH, United States

The IR TrueFISP sequence has been shown to be a promising approach for the simultaneous quantification of proton density, T1 and T2 maps. For accurate quantification, segmentation is usually necessary, leading to an increase in scan time. In this work, a full set of parameter maps was obtained in a single-shot by combining the IR TrueFISP sequence with a golden-ratio based radial trajectory and using extensive view-sharing. The effects of both magnetization transfer and the violated instantaneous RF assumption on parameter quantification were further analyzed by prolonging the RF pulses and TR (thereby reducing RF power and thus MT).

2970. T1 and T2 Quantification for Short T2 Tissues: Challenges and Solutions

Michael Carl1, Jiang Du2, Jing-Tzyh Alan Chiang2, Eric Han1, Christine Chung2

1GE Healthcare, Waukesha, WI, United States; 2University of California, San Diego

The relaxation properties T1 and T2 of MRI images are important parameters in assessment of pathology. Many musculoskeletal (MSK) tissues (cortical bone, tendon, ligaments, etc) have very short transverse relaxation times. UTE imaging of MSK tissues can pose unique challenges for the quantification of the longitudinal or transverse relaxation. We describe these challenges and offer simple solutions to help overcome them.

2971. Tandem Dual-Echo Fast Spin Echo with Inversion Recovery (Tandem-IR-DE-FSE): A Multi-Platform Pulse Sequence for Multispectral Quantitative-MRI (PD, T1, T2)

Hernan Jara1, Stephan W. Anderson1, Osamu Sakai1, Jorge A. Soto1

1Boston University School of Medicine, Boston, MA, United States

Purpose: There is great need for multi-spectral quantitative-MRI (qMRI) pulse sequences that can be readily implemented in MRI scanners of different manufacturers and field strengths. Methods: The Tandem-IR-DE-FSE sequences were implemented in GE (1.5T-SIGNA HDx) and Bruker 11.7T scanners. Results: Excellent directly-acquired and qMRI map image quality was obtained with both scanners: PD, T1, and T2 maps of the brain are of good image quality and also are give qMRI measures in good agreement with accepted values. Conclusion: The Tandem IR-DE-FSE sequence can produce multispectral qMRI maps of PD, T1, and T2 that are self co-registered, high spatial resolution, and with clinical coverage.

2972. High Resolution Multispectral QMRI Protocol: PD, T1, T2, T2*, ADC, MT

Stephan William Anderson1, Jorge A. Soto1, Hernan Jara1

1Radiology, Boston University Medical Center, Boston, MA, United States

The purpose of this study was to develop a high-resolution, multi-spectral, quantitative magnetic resonance imaging (qMRI) pulse sequence protocol to interrogate T1, T2, T2*, proton density (PD), diffusion coefficient, and magnetization transfer parameters at ultra-high field (11.7T) MRI. This multi-spectral qMRI pulse sequence was applied to a qMRI phantom containing water, agarose gels, sucrose solutions, and olive oil. Also, the protocol was applied to ex vivo liver imaging of a murine model of steatohepatitis as well as ex vivo murine brain imaging. This comprehensive, multi-spectral qMRI protocol was successfully implemented at 11.7T MRI

2973. Comparison of Magnetic Field Correlation in Brain at 1.5 and 3 Tesla

Caixia Hu1,2, Jens H. Jensen1, Casian Monaco, Kathleen Williams, Joseph A. Helpern1,2

1Radiology, New York University School of Medicine, New York, NY, United States; 2Center for Advanced Brain Imaging, Nathan S. Kline Institute, Orangeburg, NY, United States

The magnetic field correlation is theoretically predicted to scale as the square of the applied field. This was verified experimentally in brain for two subjects by scanning them at 1.5T and 3T. The magnetic field correlation was estimated by using a recently proposed MRI method based on asymmetric spin echoes. The consistency of the experimental results with the theoretical prediction constitutes an important validation for the imaging method and helps to justify its application at clinical field levels. Magnetic field correlation can be of interest for studying brain iron changes associated with neuropathologies, such as Alzheimer’s disease and multiple sclerosis.

Ultra Short TE

Hall B Tuesday 13:30-15:30

2974. Ultra-Short Echo-Time (UTE) Imaging for Early Diagnosis of Dental Demineralization

Anna-Katinka Bracher1, Christian Hofmann2,3, Said Boujraf4, Axel Bornstedt1, Erich Hell5, Johannes Ulrici5, Axel Spahr2, Volker Rasche1

1Department of Internal Medicine II, University Hospital of Ulm, Ulm, Baden-Württemberg, Germany; 2Department of Operative Dentistry, Periodontology and Pedodontics, University Hospital of Ulm, Ulm, Germany; 3Department of Internal Medicine II, University Hospital of Ulm, Ulm, Baden-Württemberg, Germany; 4Department of Biophysics and Clinical MRI Methods, Faculty of Medicine and Pharmacy, University of Fez, Morocco; 5Sirona Dental Systems GmbH, Bensheim, Germany

Due to the high mineral content, the concentration of free protons is extremely low causing only weak magnetization and due to the susceptibility interfaces in the mineral structures, the spin-spin relaxation rates results below 1ms for dentin and below 250µs for enamel. During caries lesion formation, some increase in liquid content resulting from the production of acid or caused by water penetrating into the lesion through the porous demineralized enamel layer is expected. The performance of ultra-short echo time (UTE) MRI for early assessment of lesion formation was investigated and compared to X-ray imaging.

2975. Theoretical Sensitivities of SWIFT and the Ideal Sequence (Delta Pulse-Acquire) for Ultra-Short T2

Robert Daniel O'Connell1, Steen Moeller1, Djaudat Idiyatullin1, Curt Corum1, Michael Garwood1

1Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States

A comparison is made between infinitely short RF pulses (delta), hard pulses and SWIFT using the Ernst energy equation and Bloch simulations. Simulation results are reported for each pulse sequence for on- and off-resonance systems at T1=T2. The SWIFT, delta pulse, and long T1,2 on-resonance hard-pulse sequences are described by the Ernst equations. On-resonance hard pulses have signal energy loss for short T1,2. Off-resonance hard pulses are not described by the Ernst equations. In addition to being unaffected by resonance offsets, for any flip angle the SWIFT sequence results in having a signal energy peak at shorter T1,2 than the other sequences.

2976. 3D Ultrashort Echo Time (UTE) Imaging in the Brain at 7T

Peder E. Z. Larson1, Duan Xu1, Daniel B. Vigneron1

1Radiology and Biomedical Imaging, University of California - San Francisco, San Francisco, CA, United States

Ultrashort echo time (UTE) imaging of the brain has the potential for direct detection of myelin, calcifications and other short-T2 components that are altered in neurodegenerative diseases and other neurological pathologies. Ultra high-field MRI at 7T offers improved SNR for detection of these components which generally have low signal intensity. In this project, we have developed a 3D radial UTE acquisition for 7T brain imaging providing full head coverage in just over 5 mins. Both dual-echo subtraction and off-resonant saturation pulses were applied yielding good contrast of connective tissues and white matter short-T2 components.

2977. Single Point Sequences with Shortest Possible TE – GOSPEL

David Manuel Grodzki1,2, Michael Deimling1, Björn Heismann1, Hans-Peter Fautz1, Peter Jakob2

1Magnetic Resonance, Siemens Healthcare, Erlangen, Bavaria, Germany; 2Department of Experimental Physics 5, University of Würzburg, Würzburg, Bavaria, Germany

We present a novel single point sequence, GOSPEL (Gradient Optimised Single Point Imaging with Echo-time Leveraging). Based on a RASP / SPRITE sequence, it uses the shortest possible echo-time for each acquired k-space point. Especially for clinical scanners with limited gradient strength, the reduction of the echo-time enables an improved measurement of tissues with short T2 times. We present an image of a human hand, depicting both the bone structure and tendons. The results indicate that GOSPEL can be used for bone and tendon imaging or MR-PET attenuation correction.

2978. Imaging of Renal Stones in Vitro with UTE MRI

Aya Yassin1, Ivan Pedrosa1, Michael Kearney2, Elizabeth Genega3, Neil M. Rofsky1, Robert E. Lenkinski1

1Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States; 2Urology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States; 3Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States

Renal stones have short T2 values and are therefore difficult to demonstrate when using conventional MR sequences. We utilized the UTE MR sequence to characterize renal stones in vitro. Thirty-six stones from patients were scanned, and T1 and T2 values were calculated for every stone. The results were correlated with the composition. The 21/36 visualized stones showed high signal on UTE images. Having demonstrated the feasibility of the UTE sequence for imaging renal stones we anticipate employing this technique on a wider scale to patients suspected of having renal stones, especially to those in whom it is desirable to avoid ionizing radiation exposure such as children, women of child bearing age and pregnant females.

2979. MRI Signal Delay: A Potential Probing Mechanism for Cellular Imaging in the Brain

Yongxain Qian1, Fernando E. Boada1

1MR Research Center, Radiology, University of Pittsburgh, Pittsburgh, PA, United States

This work presents new observations of the delay of MRI signal in human brain on 3T MRI scanner with ultrashort echo time (UTE) acquisitions. The MRI signal delay was related, by our hypotheses, to those parameters such as ion concentration and T2* relaxation time, that characterize cellular micro environment inside/outside a cell as well as cell membrane. An electromagnetic (EM) interaction between RF pulse and mobile ions in tissue was employed to illuminate the delay of MRI signals.

2980. Detection of Short T2 Component in Brain by SWIFT

Lauri Juhani Lehto1, Djaudat Idiyatullin2, Curtis Andrew Corum2, Michael Garwood2, Olli Heikki Gröhn1

1A. I. Virtanen Institute for Molecular Medicine, University of Kuopio, Kuopio, Eastern Finland, Finland; 2Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States

The aim of this work was to directly detect signal from the short T2 component in the brain using the SWIFT sequence that allows almost simultaneous excitation and detection. To detect the short T2 component, the overwhelming long T2 component signal was suppressed either by using long adiabatic inversion pulses or by suppressing the short T2 component and subtracting that from a normal SWIFT image. Results show relative enhancement of white matter structures in the brain. The contrast in the latter approach is interpreted to have a contribution also from MTC and thus represents combined direct and indirect detection of the short T2 pool.

Magnetization Transfer & CEST

Hall B Wednesday 13:30-15:30

2981. Pulsed CEST for the Quantification of PH

Kimberly Lara Desmond1, Greg J. Stanisz1,2

1Medical Biophysics, University of Toronto, Toronto, Ontario, Canada; 2Imaging Research, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada

We present a method for the quantification of pH using a pulsed chemical exchange saturation transfer (CEST) method. Experimental data is from a phantom model consisting of 1M ammonium chloride in 10mM citric acid buffer for the modification of pH. This data is fit using a two-compartment Bloch equation model of exchange in the presence of off-resonance excitation. A linear relationship is observed between the log of the fitted exchange rate and the true pH of the phantom.

2982. Ytterbium (Yb)-Based PARACEST Agent: Feasibility of CEST Imaging on a Clinical 3.0 T Scanner

Yukihisa Takayama1, Akihiro Nishie1, Takashi Yoshiura1, Tomohiro Nakayama1, Eiki Nagao1, Naoki Kato2, Satoshi Yoshise2, Shutaro Saiki2, Dirk Burdinski3, Holger Grull3, Jochen Keupp3, Hiroshi Honda1

1Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; 2Philips Electronics Japan, Tokyo, Japan; 3Philips Research Europe, Hamburg, Germany

Chemical Exchange-dependent Saturation Transfer (CEST) is a novel contrast mechanism for magnetic resonance (MR) imaging, but it is not yet common in clinical practice. We investigated the feasibility of CEST imaging on a clinical MR scanner by in vitro study using a ytterbium complex of paramagnetic CEST agents. The CEST effect could be observed at specific offset frequencies. In addition, it increased and decreased depending on the degrees of concentration, pH or solution. We showed the clinical potential of CEST imaging using these agents, but further modifications, such as optimized presaturation RF pulse, imaging protocols or other techniques, remain necessary.

2983. Magnetic Resonance Imaging of the Neurotransmitter GABA in-Vivo

Kejia Cai1, Mohammad Haris1, Anup Singh1, Feliks Kogan1, Prianka Waghray2, Walter Witschey1, Hari Hariharan1, John A. Detre3, Ravinder Reddy1

1CMROI, Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States; 2Department of Biology, Wake Forest University, Winston-Salem, NC, United States; 3Department of Neurology, and Center for Functional Neuroimaging, University of Pennsylvania, Philadelphia, PA, United States

Gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter of the brain and plays a critical role in multiple central nervous system diseases. The objective of this study was to characterize the chemical exchange saturation transfer (CEST) effect of the -NH2 protons of GABA and to demonstrate GABA imaging in the human brain at 7T. The Z-spectrum of GABA showed a pH sensitive asymmetry around ~2.75 ppm downfield to the water resonance. CEST imaging of healthy human volunteers clearly showed the distribution of GABA CEST contrast in different regions of the brain with negligible contrast from cerebrospinal fluid

2984. CEST and Sodium Imaging of Glycosaminoglycans In-Vivo on the 3T: Preliminary Results

Elena Vinogradov1, Alexander Ivanishev1, Aaron K. Grant1, Ron N. Alkalay2, David B. Hackney1, Robert E. Lenkinski1

1Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States; 2Department of Orthopedic Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States

Quantitative assessment of Glycosaminoglycans (GAGs) in the clinical environment can assist with characterization of disorders associated with cartilage degradation and loss. Sodium imaging and Chemical Exchange Saturation Transfer for GAG detection (gagCEST) are two of the several methods for GAG assessment. Both methods rely on the endogenous effects. However, sodium imaging suffers from low sensitivity and requires specialized hardware. GagCEST is a new method still in the validation phase. Both methods were implemented on the clinical 3T scanner for the purpose of the validation of the techniques and the correlation between GAG state in-vivo as assessed using the two methods.

2985. Detection of Glycosaminoglycans Using Positive CEST Approach

Elena Vinogradov1, Robert E. Lenkinski1

1Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States

Chemical Exchange Saturation Contrast utilizes selective presaturation of a small pool of exchanging protons and is manifested in the decrease of the free water signal. Recently, CEST method has been applied successfully to detect glycosaminoglycans (GAG) in cartilage. CEST contrast is negative, resulting in decreased signal from areas with high agent (GAG) concentration. An alternative scheme, positive CEST (pCEST), results in the background suppression and positive contrast when signal is increased due to the presence of the exchanging agent. Here we evaluate application of the pCEST to detect GAG in solutions and ex-vivo samples.

2986. Improving Amide Proton Transfer Imaging with Dual Echo B0 Mapping for Field Inhomogeneity Correction at 3T

Wenbo Wei1, Guang Jia1, Steffen Sammet1, Peter Wassenaar1, Jinyuan Zhou2, Michael Knopp1

1Department of Radiology, The Ohio State University, Columbus, OH, United States; 2Department of Radiology, Johns Hopkins University, Baltimor, MD, United States

In this study, dual echo B0 mapping was used in Amide Proton Transfer (APT) imaging for correcting B0 inhomogeneity with fewer data points which will lead to approximately one third of the current scan time and thus higher resolution. CEST spectrum, MTRasym curve and MTRasym (3.5ppm) encoded color maps of the proposed APT method were compared to a conventional method. The proposed method offers a more accurate MTR asym curve shape and a better determination of the water resonance frequency which allows a better MTRasym calculation.

2987. Optimization of RF Saturation to Minimize B0 Inhomogeneity Effects in Pulsed Amide Proton Transfer Imaging

Rachel Scheidegger1,2, Elena Vinogradov1,3, David C. Alsop1,3

1Radiology, Beth Israel Deaconess Medical Center, Boston, MA, United States; 2Health Sciences and Technology, Harvard-MIT, Cambridge, MA, United States; 3Radiology, Harvard Medical School, Boston, MA, United States

Off-resonance errors due to magnetic field inhomogeneity are a major challenge for amide proton transfer imaging. Two-pool Bloch equation simulations were used to optimize the timing for pulsed APT imaging with two different subtraction methods. Simulations indicate that the pulse width and interpulse delay as well as the subtraction method used are key factors in optimizing APT for insensitivity to magnetic field inhomogeneity.

2988. Rapid CEST Detection Using EPI

Nevin McVicar1, Alex X. Li2, Robert Hudson3, Martyn Klassen2, Robert Bartha1,2

1Medical Biophysics, University of Western Ontario, London, ON, Canada; 2Centre of Functional and Metabolic Imaging, Robarts Research Institute, London, ON, Canada; 3Chemistry, University of Western Ontario, London, ON, Canada

An Echo-planar imaging (EPI) pulse sequence was developed to detect CEST paramagnetic contrast. The EPI PARACEST sequence included a 2.5s CEST saturation pulse, followed by a ~ 26ms echo-train. Signal to noise ratio (SNR), CEST effect, and CEST efficiency for EPI CEST sequence were compared to fast spin-echo (FSE) CEST and fast low angle shot (FLASH) CEST in a phantom containing 10 mM Eu3+-DOTAM-Gly-Phe. EPI CEST, provided high temporal resolution and SNR while fully maintaining CEST effect due to the short readout times. Decreasing readout bandwidth had no significant impact on acquisition time or CEST contrast but increased image SNR.

2989. Optimized PARACEST Signal Detection by Echo-Planar Imaging

Adrienne Elizabeth Campbell1,2, Alex Li1, Craig Jones3,4, Robert Bartha1

1Centre for Functional and Metabolic Mapping, Robarts Research Institute, University of Western Ontario, London, Ontario, Canada; 2Centre for Advanced Biomedical Imaging, University College London, London , Greater London, United Kingdom; 3F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, John Hopkins University, Baltimore, MD, United States; 4Centre for Functional and Metabolic Mapping, Robarts Research Institute, University of Western Ontario, London , Ontario, Canada

Paramagnetic chemical exchange saturation transfer (PARACEST) contrast agents are being developed for in-vivo MRI. In this study, an accurate in-vivo MRI simulator was developed and used to optimize a time-course Echo-Planar Imaging (EPI) scheme. An 8-shot EPI sequence was simulated for the detection of 100μM and 1mM solutions of Dy3+-DOTAM-GlyLys in vivo. A dynamic EPI scheme, which alternates between a PARACEST EPI sequence that saturates on the bound water pool and a control sequence, was optimized to minimize the SNR requirements for detection. It was determined that EPI schemes may be feasible for PARACEST detection in-vivo.

2990. Optimization of Pulsed Saturation for CEST Imaging in Standard Clinical MR Scanners

Benjamin Schmitt1, Moritz Zaiss1, Peter Bachert1

1Medical Physics in Radiology, German Cancer Research Center, Heidelberg, Germany

If CEST imaging is employed in clinical MR systems hardware restrictions and SAR regulations exclude the possibility to generate a steady-state for saturation through CW irradiation. Pulsed saturation, which is used instead, holds disadvantages in preparation time and frequency coverage compared to CW. A narrow frequency coverage while maintaining SAR boundaries as well as short scan times are essential for clinical CEST imaging. We propose an effective pulsed saturation scheme which meets both requirements. The scheme is based on simulations and its effectiveness was verified experimentally.

2991. Detection of Chemical Exchange Saturation Transfer (CEST) Contrast Using Frequency Transfer

Joshua Friedman1,2, Michael McMahon1, James Stivers2, Peter Christiaan van Zijl1

1Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, United States; 2Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, United States

Currently, CEST compounds are detected using radiofrequency (RF) based saturation transfer followed by asymmetry analysis of the magnetization transfer spectrum. We report an approach that, instead of saturation transfer, employs a series of so-called label-transfer modules (LTMs), in which frequency labeling and consecutive transfer of labeled protons to water is achieved. No asymmetry analysis is needed and exchangeable protons at multiple frequencies can be detected simultaneously through the water proton signal, while maintaining specific frequency information of the individual solute protons. As a first example, the method is applied to a DNA sample and the theory confirmed experimentally.

2992. Chimera Averaging for Robust SSFP Magnetization Transfer Contrast Imaging (MT-Chimera)

Christian Stehning1, Peter Boernert1

1Philips Research Europe, Hamburg, Germany

Balanced SSFP shows a pronounced magnetization transfer (MT) contrast, which allows for quantitative MT imaging. However, very accurate shimming is needed to cope with offresonances particularly at prolonged TR. A novel approach based on offset averaging of SSFP images with a linear frequency response is investigated. It presents a robust means for MT SSFP imaging with prolonged TR. This approach may be appealing in anatomic regions where susceptibilities cannot be addressed by shimming alone.

2993. Magnetization Transfer Contrast Enhancement Due to Intermolecular Multiple Quantum Coherences - Quantitative Analysis and Tissue Dependency

Sebastian Baier1, Stefan Kirsch1, Lothar R. Schad1

1Department of Computer Assisted Clinical Medicine, Heidelberg University, Mannheim, Germany

This work shows a quantitative analysis of magnetization transfer contrast (MTC) enhancement due to intermolecular multiple quantum coherences (iMQC). Therefore a measurement over a wide range of offset frequencies of the MT pulses was performed for different orders of iMQCs. This data was analyzed by fitting both the standard MT 2 Pool model and a modified model including the order of coherence of the iMQCs. Moreover the tissue dependency of the contrast enhancement was investigated.

2994. Theoretical Study of a New Saturation Technique for Magnetization Transfer Experiments

Moritz Wilhelm Zaiss1, Benjamin Schmitt1, Bram Stieltjes, Peter Bachert1

1Medical Physics in Radiology, DKFZ, Heidelberg, Germany

The best method to evaluate magnetization transfer and chemical exchange transfer are saturation transfer experiments with constant saturation power. Our approach is a varying saturation power depending on the saturation offset. Hereby, the solution of the Bloch-McConnell equations changes fundamentally. Theoretical studies show that off-resonant pools can be isolated from the water resonance while the intensity of the transfer effect remains unchanged. Numerical simulations with pulsed saturation returned similar results. So, the application on clinical scanners with pulsed saturation promises a more robust way of measuring and evaluating z-spectra than common z-spectrum asymmetry analysis.

2995. Preliminary Investigation of the Use of Parallel RF Transmission in MTR Measurement at 3.0T

Rebecca Sara Samson1, Matthew Clemence2, Xavier G. Golay3, Claudia A M Wheeler-Kingshott1

1NMR Unit, Department of Neuroinflammation, UCL Institute of Neurology, London, United Kingdom; 2Philips Clinical Science Group, Philips Healthcare, Guildford, United Kingdom; 3NMR Unit, Department of Brain Repair and Rehabilitation, UCL Institute of Neurology, London, United Kingdom

RF B1 transmit field non-uniformity, caused primarily by skin depth and dielectric resonance effects, is a large source of error in quantitative MR measurements made at 3.0T. We investigated the possibility that B1 errors could be reduced using dual transmission by measuring the MTR and B1 with and without dual transmission. We present preliminary data acquired on three healthy subjects indicating that it may be possible to reduce inter-subject variation in MTR histogram peak locations via the use of dual transmission at 3.0T. This could be an important consideration when designing future long-term clinical studies using quantitative MRI outcome measures.

2996. Orientation Dependence of Magnetization Transfer in Human White Matter.

Dirk K. Müller1, André Pampel1, Harald E. Möller1

1Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany

We present an investigation of the dependence of quantitative magnetization transfer (qMT) on fibre orientation. QMT parameters obtained from experiments using pulsed off-resonance irradiation were correlated to the orientation of the diffusion tensor obtained from DTI data. In particular, we observed a correlation between the fiber orientation with respect to B0 and the transverse relaxation rate of the semi-solid pool (T2b).

2997. Quantification of the Magnetization Transfer Phenomenon in the Human Head at 7T

Olivier E. Mougin1, Penny A. Gowland1

1Sir Peter Mansfield Magnetic Resonance Centre, School of Physics & Astronomy,University of Nottingham, Nottingham, Nottinghamshire, United Kingdom

Magnetization Transfer and related effects such as CEST are important sources of contrast in MRI. Sensitivity and increase spectral resolution make possible the measurement of MT effects at 7T in vivo. We used pulsed saturation with Turbo Field Echo readout with a range of saturation offset frequencies on the approach to steady-state, providing data that can be used to measure MT parameters at 7T in a reasonable imaging time at a resolution of 1.25mm isotropic.

2998. A Simple Iterative Reduction Method for Optimization of Quantitative Magnetization Transfer Imaging

Ives R. Levesque1, John G. Sled2, G Bruce Pike1

1Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada; 2Mouse Imaging Centre, Hospital For Sick Children, Toronto, Ontario, Canada

A method is presented for the selection of an optimal acquisition scheme for quantitative magnetization transfer imaging using pulsed off-resonance saturation. This method is based on the iterative reduction of a discrete sampling of the Z-spectrum. In vivo results demonstrate that optimized sampling improves parameter map quality and longitudinal reproducibility. The reduction method avoids clustering and repeated points, an attractive feature for the purpose of MT model validation. The optimal number of MT weightings is also investigated.

2999. Measuring Scan-Rescan Reliability in Quantitative Brain Imaging Reveals Instability in an Apparently Healthy Imager and Improves Statistical Power in a Clinical Study.

Becky Ilana Haynes1, Nick G. Dowell1, Paul S. Tofts1

1Clinical Imaging Sciences Centre, Brighton and Sussex Medical School, Brighton, United Kingdom

Repeatability of MTR and ADC brain histograms of healthy volunteers in our centre showed disturbingly large differences, even though the scanner was producing high quality images. Such instrumental variation could mask small between-group differences in a cross-sectional study, and increase the number of participants needed to see an effect. Repeat scans in phantoms and healthy controls highlighted the variability and showed when the problem had been fixed. Our current normal standard deviations are at the lower end of the published range. Ongoing QA for quantitative studies should include explicit measurement of short- and long-term repeatability in controls.

3000. Reconstruction of Bound Pool Fraction Maps from Subsets of Cross-Relaxation Imaging Data at 3.0 T: Accuracy, Time-Efficiency and Error Analysis

Hunter R. Underhill1,2, Chun Yuan1, Vasily L. Yarnykh1

1Radiology, University of Washington, Seattle, WA, United States; 2Bioengineering, University of Washington, Seattle, WA, United States

In this study, we compare strategies for the time-efficient acquisition of the bound pool fraction in the in vivo human brain at 3.0 T. The bound pool fraction can be accurately estimated using only two off-resonant magnetization transfer data points by applying appropriate, field-strength specific constraints to the transfer rate constant and transverse relaxation parameters. In so doing, whole-brain, three-dimensional, high-resolution f-maps can be obtained in a clinically acceptable scan time. Simulations demonstrate that the effects of parameter constraints induce minimal error in determining f in grey matter, white matter and multiple sclerosis lesions.

3001. Five-Site Modeling of Protons Chemical Exchange Processes for in Vivo CEST-Based Molecular Imaging

Julien Flament1, Benjamin Marty1, Céline Giraudeau1, Sébastien Mériaux1, Julien Valette1, Christelle Médina2, Caroline Robic2, Marc Port2, Franck Lethimonnier1, Gilles Bloch1, Denis Le Bihan1, Fawzi Boumezbeur1

1NeuroSpin, I²BM, Commissariat à l'Energie Atomique, Gif-sur-Yvette, France; 2Guerbet, Research Division, Roissy-Charles de Gaulle, France

LipoCEST are a new class of contrast agents for CEST-MRI which provide a tremendous amplification factor but suffer from a quite small chemical shift (2-28 ppm) compared to paramagnetic complexes. Consequently, their detection in vivo is hampered by endogenous Magnetization Transfer contrast. It is therefore important to separate specific LipoCEST signal from endogenous background coming from macromolecules. Thus in this study, we propose to characterize water exchange processes using a five-site model by measuring and fitting the Z-spectrum of each tissular compartment of mouse brain in order to achieve quantitative CEST imaging with LipoCEST contrast agents.

3002. Detection of Proton Chemical Exchange Between Metabolites and Water Using T1ρ MRI

Feliks Kogan1, Walter Witschey1, Keijia Cai1, Mohammad Haris1, Ravinder Reddy1

1Center for Magnetic Resonance and Optical Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States

Imaging of chemical exchange processes is important as it allows for quantification of specific metabolites. In this study, we developed a new method based on T1ρ MRI to create image contrast and quantify the exchange of protons between metabolites and water. We showed that this method is responsive to changes in concentration as well as pH. The sensitivity of this technique scales quadratically with static magnetic field and becomes much more valuable as high field magnets become more widely available clinically.

3003. Comparison of Chemical Exchange Saturation Transfer (CEST) and T1ρ MRI for Measurement of Proton Chemical Exchange Between Metabolites and Water at 7T

Feliks Kogan1, Walter Witschey1, Keijia Cai1, Mohammad Haris1, Ravinder Reddy1

1Center for Magnetic Resonance and Optical Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States

Recent work on imaging chemical exchange processeshas been focused on exploitingchemical exchange saturation transfer (CEST). T1ρ imaging is another imaging technique which depends on chemical exchange which can be used to image metabolites based on their proton exchange properties. In this study, we compared the sensitivities of these two techniques for measuring metabolites based on proton exchange. We observed that at 7T, T1ρ imaging has a higher sensitivity to exchanges processes compared to that of CEST.

3004. Study of Chemical Exchange in the Intermediate Exchange Regime: A Comparison of Spin-Locking and CEST Techniques

Joonas Arttu Autio1,2, Tao Jin3, S-G Kim3,4, Takayuki Obata1

1Department of Biophysics, National Institute of Radiological Sciences, Chiba, Japan; 2Department of Neurobiology, University of Kuopio, Kuopio, Finland; 3Department of Radiology, University of Pittsburgh, Pittsburgh, PA, United States; 4Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, United States

Previous study has demonstrated an indirect MRI detection of hydroxyl protons of small metabolites via chemical exchange saturation transfer. We used an on-resonance spin-locking (SL) pulse to detect proton exchange for hydroxyl-, amide- and amine-phantoms, and a protein sample. Analysis of spin-lattice relaxation rate in the rotating frame dispersion over a range of SL B1 fields, resulted in robust estimates for intermediate proton exchange rates and exchangeble proton site populations. Our results suggest that SL technique with on-resonance irradiation is not sensitive to very slow exchange, but may be more suited for quantitative study in the intermediate exchange regime.

3005. A Fast, Quantitative T1ρ Imaging Method

Timo Liimatainen1, Olli Gröhn2

1Department of Biotechnology and Molecular Medicine, University of Kuopio, Kuopio, Finland; 2Department of Neurobiology, University of Kuopio, Kuopio, Finland

A pulse sequence based on gradient echo design was modified to include four hyperbolic secant pulses, following by a signal acquisition. This was repeated four times to obtain a T1ρ weighted signal intensity curve with incrementally increasing spin-lock time for single phase encoding step. T1ρ relaxation times were compared between developed method and spin echo readout with a T1ρ preparation pulse train in mice brains. Similar T1ρ values were obtained with both methods. The developed method allows acquisition of several incremented spin-lock times within one repetition time enabling faster quantization of T1ρ and/or decreased specific absorption rates.

3006. Evaluating Exchange Processes in the Human Brain: Magnetization Transfer Vs Adiabatic Rotating Frame Relaxation Methods

Silvia Mangia1, Michael Garwood1, Steen Moeller1, Dennis Sorce1, Kamil Ugurbil1, Shalom Michaeli1

1CMRR - Dept. of Radiology, University of Minnesota, Minneapolis, MN, United States

In the present work we investigate the different sensitivity to exchange processes generated at 4T by a variety of preparation pulses. To this aim, we quantitatively analyzed images from the human brain acquired by preparing magnetization with an off-resonance hard pulse, to exploit the so-called magnetization-transfer effect, or by preparing magnetization with a series of adiabatic pulses with different modulation functions, to exploit adiabatic rotating frame relaxation mechanisms. Results demonstrate that the two approaches are sensitive to completely different regimes of exchange, thus providing complimentary information to characterize the tissue.

3007. Measuring T1ρ Changes Related to Acidosis and Alkalosis

Hye Young Heo1, Nader Dahdaleh1, Daniel Thedens1, Bradley Bolster2, John Wemmie1, Vincent Magnotta1

1University of Iowa, Iowa City, IA, United States; 2Siemens Healthcare, Rochester, MN, United States

The purpose of this study is to determine the ability of magnetic resonance (MR) imaging to assess regional pH levels. Both phantom and mouse models were used to evaluate pH sensitive changes in T1ρ imaging. A linear relationship was observed between T1ρ time and pH. In the mouse model, widespread increases in T1ρ times during CO2 inhalation were found consistent with the expected acidosis, whereas reduced T1ρ times during HCO3- injection were found to be consistent with the expected alkalosis.

3008. Computer Simulations of 3D MPRAGE in Human Brain with Inclusion of Inadvertent Magnetization Transfer Effects

Gerald Matson1, Hui Liu1

1CIND, Veterans Affairs Medical Center, San Francisco, CA, United States

Magnetization transfer (MT) effects in the human brain occur when there is magnetization transfer between the free and bound water pools associated with gray and white matter. These MT effects can become significant, particular when longer excite pulses are used, for example, to induce uniform tip angles in the presence of non-uniform RF fields. Therefore, we developed a simulation program written in Matlab to calculate these MT effects, and to simulate the 3D MPRAGE experiment. The simulations show that the MT effects must be taken into account when longer excite pulses are used in the 3D MPRAGE experiment.

7T MRI

Thursday 13:30-15:30

3009. High Resolution Whole Head 3D Susceptibility Mapping at 7T: A Comparison of Multi-Orientation and Single Orientation Methods

Samuel James Wharton1, Richard Bowtell1

1Sir Peter Mansfield Magnetic Resonance Centre, University of Nottingham, Nottingham, United Kingdom

Phase images generated using gradient echo techniques at high field show excellent contrast related to variation of magnetic susceptibility across brain tissues. Calculating susceptibility maps from phase data is made difficult by the ill-posed nature of the deconvolution problem which must be solved. Careful conditioning is therefore required. Here, we compare the performance of three conditioning strategies ((i) combination of data acquired at multiple orientations; (ii) k-space thresholding of data acquired at a single orientation; (iii) incorporation of structural information using corresponding modulus data) in the calculation of susceptibility maps from high-resolution phase images of the brain and a phantom.

3010. Basis for Contrast Enhanced T1- Weighted Imaging Using SE at High Field

Niravkumar Darji1, Michel Ramm1, Oliver Speck1

1Department Biomedical Magnetic Resonance, Institute for Experimental Physics, Otto-von-Guericke University Magdeburg, Magdeburg, Germany

Aim of this study was to reduce fat signal without using fat saturation pulse. This task was achieved by modification of RF pulse in SE sequence. Different bandwidth of the refocusing pulse allows suppression of fat signal without increased SAR in high resolution SE imaging. The reduced fat signal with longer refocusing pulse duration is evident from in-vivo experiments.

3011. Adiabatic Magnetization Preparation Pulse for T2-Contrast at 7 Tesla

Priti Balchandani1, Daniel Spielman1

1Radiology, Stanford University, Stanford, CA, United States

T2-weighted sequences such as Fast Spin Echo are highly susceptible to the B1-inhomogeneity and are SAR-intensive at 7T. We present an alternative method to obtain T2-contrast at 7T which utilizes an adiabatic magnetization preparation (AMP) pulse. The AMP pulse is a 0° BIR-4 pulse with delays inserted between segments to introduce T2-decay. Phantom and in vivo experiments show that the AMP pulse provides more uniform SNR and T2-contrast over the excited slice. The AMP pulse is suitable for use in a volumetric fast gradient echo sequence.

3012. Comparison of Reduced FOV Techniques for High Resolution Imaging at 7T

Christopher Joseph Wargo1, Marcin Jankiewicz1, John C. Gore1

1Vanderbilt University Institute of Imaging Science, Nashville, TN, United States

High-resolution MR imaging benefits from ultra-high field strength such as at 7T due to improvement in signal, but requires acquisition of a large number of voxels. This increases the scan duration, and thus field and time dependent artifacts, and reduces temporal resolution for functional studies. Reduction of the FOV enables scan times to be shortened, but introduces tradeoffs between SNR, scan efficiency, SAR, and image artifacts. In this abstract, we compare a subset of selective excitation approaches including STEAM, PRESS, OVS, and spectral spatial pulses, for reduced-FOV resolution improvement in phantoms using a human 7T system.

3013. Towards the Accurate and Precise Assessment of SNR in Vivo at 7T

Josef Habib1,2, Dorothee P. Auer1, Richard W. Bowtell2

1Academic Radiology, University of Nottingham, Nottingham, Nottinghamshire, United Kingdom; 2Sir Peter Mansfield Magnetic Resonance Centre, University of Nottingham, Nottingham, Nottinghamshire, United Kingdom

The Signal-to-Noise ratio (SNR) is a fundamental and critical data quality measure in MRI, with several investigations dedicated to devising and validating optimized measurement techniques. While the introduction of higher field strength MRI systems is expected to impact attainable SNR levels, this study shows that the prevalent technique for measuring SNR in vivo performs sub-optimally at 7 Tesla, due to artifacts presumably caused by the increased sensitivity to subject or physiological motion. Here we propose the use of an alternative measurement technique for increased robustness, after quantitatively evaluating its precision and accuracy.

3014. A Fast Spin-Echo Multi Gradient-Echo Sequence to Reduce Distortions on T2-Weighted Images at High Field

Ludovic de Rochefort1, Martine Guillermier1, Diane Houitte1, Marion Chaigneau1, Philippe Hantraye1, Vincent Lebon1

1MIRCen, I2BM, DSV, CEA, Fontenay-aux-Roses, France

Susceptibility-induced magnetic field and chemical shift increase image distortion at high field. In a 2D FSE sequence, increasing the bandwidth to limit these artifacts implies degrading SNR by reducing the ratio of the observation time (TO) per unit time rapidly reaching SAR and gradient duty cycle limitations. We propose to replace the readout within the 180 pulses by a train of gradient echoes with a larger bandwidth and the same TO. It is shown in vivo on rat brain that susceptibility induced distortions are suppressed by this approach while preserving SNR and contrast.

Phase Imaging

Monday 14:00-16:00

3015. Removing Air-Tissue Artifacts in Phase Images by Modulating the Air Susceptibility

José P. Marques1,2, Rolf Gruetter1,3

1Centre d'Imagerie BioMédicale, EPFL, Lausanne, Vaud, Switzerland; 2Department of Radiology, University of Lausanne, Lausanne, Vaud, Switzerland; 3Department of Radiology, Universities of Lausanne and Geneva, Switzerland

In this work, the susceptibility of air was varied by changing its oxygen fraction. Such a variation of the air susceptibility allowed to exclusively map the contribution from oxygen towards the measured frequency shift maps in phantoms and volunteers. This allowed removal of a significant part of the observed frequency shift around air-water interfaces, making the frequency shift maps more specific to their rich tissue contrast.

3016. Myelin as a Primary Source of Phase Contrast Demonstrated in Vivo in the Mouse Brain

Nicoleta Baxan1, Laura-Adela Harsan1, Iulius Dragonu1, Annette Merkle1, Juergen Hennig1, Dominik von Elverfeldt1

1Diagnostic Radiology, Medical Physics, University Hospital Freiburg, Freiburg, Germany

While most of MRI studies are focused on the magnitude data, the phase contrast has only recently proved its ability to improve the contrast to noise in high-resolution images at high-field strength. The origin of phase contrast between white matter (WM) and gray matter (GM) has been widely discussed; several sources were suggested including paramagnetic blood deoxyhemoglobin, tissue iron concentrations, water-macromolecules exchange or tissue myelin content. In the present study we examine the contribution of tissue myelin content to the phase contrast by exploiting the frequency shift variation in a chronic model of cuprizone induced demyelination.

3017. Phase Imaging: A Novel Tool for Myelin Quantification.

Gregory A. Lodygensky1, Rajika Maddage2, Alexandra Chatagner3, Petra S. Hüppi3, José Pedro Marques2, Stephane V. Sizonenko3, Rolf Gruetter2

1Pediatrics, Pediatric and Neonatal ICU, University of Geneva, Geneva 14, Switzerland; 2Laboratory for Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland; 3Pediatrics, Division of Child Growth & Development, University of Geneva, Geneva, Switzerland

Phase imaging may allow fast and accurate myelin quantification at high resolution. A quantitative MRI-histology study of myelination on the developing rat brain.

3018. Chemically Selective Asymmetric Spin-Echo EPI Phase Imaging for Internally Referenced MR Thermometry

Markus Nikola Streicher1, Andreas Schäfer1, Bibek Dhital1, Dirk Müller1, Robin Martin Heidemann1, Andre Pampel1, Dimo Ivanov1, Robert Turner1

1Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany

We implemented a novel spin-echo EPI sequence that can acquire phase images of different chemically-shifted protons at the same slice positions. Chemical selection was achieved by applying different slice-select gradient amplitudes for excitation and refocusing RF pulses, and phase sensitivity was obtained using an asymmetric EPI readout. MR Thermometry was then performed on a mixture of water and dimethyl sulfoxide (DMSO), which has a proton chemical shift of -2 ppm from water. The two compounds were then imaged alternately, water for temperature sensitivity and DMSO to monitor field changes. Fat can also be selectively imaged as a reference compound.

3019. A Novel Method of Increasing the Contrast to Noise Ratio of Phase Images Using Balanced SSFP

Jongho Lee1, Masaki Fukunaga1, Jeff H. Duyn1

1Advanced MRI/LFMI/NINDS, National Institutes of Health, Bethesda, MD, United States

A new method of generating phase contrast is proposed. Using balanced SSFP sequence a significant contrast to noise ratio improvement was achieved. Using this method, the line of Genari in the visual cortex was shown at 3 T in a high resolution.

SSFP

Hall B Tuesday 13:30-15:30

3020. Balanced Binomial-Pulse Steady-State Free Precession (BP-SSFP) for Fast, Inherently Fat Suppressed, Non-Contrast Enhanced Angiography

Garry Liu1, Venkat Ramanan2, Graham Wright1

1University of Toronto, Toronto, ON, Canada; 2Sunnybrook Health Sciences Centre, Toronto, ON, Canada

Fat signal suppression is essential for MR angiography. In this work, we present a generalized design of a 1-2-1 binomial pulse SSFP (BP-SSFP) sequence, and the trade-off between TR reduction, water SNR, and water/fat CNR. We apply our method to achieve a short scan time, provide steady-state fat suppression, maintain high SNR, and restrict banding artifacts for peripheral MR angiograms.

3021. Balanced SSFP Profile Asymmetries Reflect Frequency Distribution Asymmetries: Evidence from Chemical Shift Imaging (CSI)

Way Cherng Chen1, Rob H Tjissen1, Chrsitopher T Rodgers2, Jamie Near1, Karla L Miller1

1FMRIB, University of Oxford, Oxford, United Kingdom; 2OCMR, University of Oxford, Oxford, United Kingdom

Steady-state free precession (SSFP) is characterized by strong signal dependence on resonance frequency often described by the SSFP frequency profile.This profile has a well known symmetric shape in a homogeneous voxel but it becomes asymmetric in an inhomogeneous voxel. The SSFP profile can be modeled as the convolution of the homogeneous profile with the frequency distribution. In this study, CSI lineshape from normal white matter tracts was convolved with the homogeneous profile obtain a predicted SSFP asymmetry profile. The predicted SSFP asymmetry profile was found to be in good agreement with the measured SSFP asymmetry profile.The ability of SSFP profile to amplify small frequency shifts makes it a promising contrast mechanism for probing tissue microstructures.

3022. Off-Resonance Banding Maps with Low Flip Angle Balanced Steady-State Free Precession

Abbas Nasiraei Moghaddam1,2, J Paul Finn1, Daniel B. Ennis1

1Radiology, UCLA, Los Angeles, CA, United States; 2Bioengineering, Caltech, Pasadena, CA, United States

Balanced steady-state free precession (bSSPF) is widely used for clinical exams. The off-resonance sensitivity, in particular, limits the use of bSSFP for clinical exams at field strengths greater than 1.5T. Herein we highlight the signal characteristics of the bSSFP pulse sequence for high and low flip angles in regions that are on- and off-resonance. Low flip angle bSSFP can be used to map off-resonance bands with bright image contrast. This is useful for discriminating image features that have low bSSFP signal intensity when high flip angles are employed and regions of off-resonance.

3023. Radio Frequency (B1) Field Mapping at 7T Using 3D SE/STE EPI Technique

Antoine Lutti1, Chloe Hutton1, Jorg Stadler2, Oliver Josephs1, Oliver Speck3, Claus Tempelmann4, Johannes Bernarding5, Nikolaus Weiskopf1

1Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, London, United Kingdom; 2Special Lab Non-Invasive Brain Imaging, Leibniz Institute for Neurobiology, Magdeburg, Germany; 3Dept. Biomedical Magnetic Resonance, Institute for Experimental Physics , Otto-von-Guericke University, Magdeburg, Germany; 4Department of Neurology, Otto-von-Guericke University, Magdeburg, Germany; 5Institute for Biometry and Medical Informatics, Faculty of Medicine, Otto-von-Guericke-University, Magdeburg, Germany

Spatial inhomogeneities in the radio-frequency (RF) field (B1) increase with field strength affecting quantification and image contrast. Fast and robust whole-brain B1 mapping methods are therefore essential to correct for B1 inhomogeneities at ultra-high fields. Here we optimize a SE/STE 3D EPI method for rapid B1 mapping at 7T, addressing severe off resonance effects and reducing sensitivity to transverse coherence effects. We demonstrate the robustness of this B1 mapping technique and illustrate its accuracy by correcting for B1 inhomogeneities in T1 maps.

3024. Transient Balanced SSFP Imaging with Increased Signal by Variable Flip Angles

Pauline W. Worters1, Brian A. Hargreaves1

1Stanford University, Stanford, CA, United States

This work presents a method for calculating variable flip angles for balanced (or fully refocused) steady state free precession (bSSFP) acquisition to generate echoes at predefined amplitudes. The main advantage is to allow for transient stage imaging with minimal artifacts and with increased signal. The variable flip angle calculation was applied to provide temporally uniform echo amplitudes. A non-contrast enhanced MRA acquisition, inflow inversion recovery (IFIR) bSSFP, was used to demonstrate the method; the resulting angiograms show improved signal and small vessel depiction.

3025. Analysis of the Transient Phase of Balanced SSFP with Non-Continuous RF for Cardiac Imaging

Glenn S. Slavin1

1Applied Science Laboratory, GE Healthcare, Bethesda, MD, United States

An analytical expression for the transient phase of a segmented, ECG-gated, non-continuous-RF, balanced SSFP sequence is presented. The results provide a means for true quantification of T1 and T2 for Look-Locker-based cardiac acquisitions.

3026. Region-Growing Reconstruction for Large-Angle Multiple-Acquisition BSSFP

Brady Quist1, Brian A. Hargreaves2, Glen R. Morrell3, Garry E. Gold2, Neal K. Bangerter1

1Department of Electrical & Computer Engineering, Brigham Young University, Provo, UT, United States; 2Department of Radiology, Stanford University, Stanford, CA, United States; 3Department of Radiology, University of Utah, Salt Lake City, UT, United States

A novel method for simultaneously suppressing fat and reducing bSSFP banding artifacts in the presence of field inhomogeneity was recently presented, called large-angle multiple-acquisition (LAMA) bSSFP. LAMA bSSFP requires the acquisition of two phase-cycled SSFP acquisitions and a field map, although previous work has suggested that an intelligent region-growing algorithm could replace field-map acquisition. In this work, we present such a region-growing algorithm, and demonstrate that LAMA bSSFP can perform effectively without the acquisition of a field map. Results are presented in the lower leg of a normal volunteer.

3027. High-Resolution 3D Isotropic Black-Blood Imaging with T2prep Inversion Recovery: Comparison Between FSE and SSFP

Keigo Kawaji1, Thanh D. Nguyen2, Beatriu Reig2, Pascal Spincemaille2, Priscilla A. Winchester2, Martin R. Prince2, Yi Wang1,2

1Biomedical Engineering, Cornell University, Ithaca, NY, United States; 2Radiology, Weill Cornell Medical College, New York, NY, United States

T2prep Inversion Recovery (T2IR) is a magnetization preparation technique that combines two preparations: T2prep and Inversion Recovery, in order to provide both T1 and T2 contrasts. Subsequently, T2IR provides flow-insensitive global black-blood suppression suited for slow flow at the expense of SNR, being suitable for 3D volumetric black-blood imaging of vessel walls where slow blood flow is observed. In this study, we examined the performance of using a T2IR preparation in both FSE and SSFP sequences to image a large 3D coronal volume (20cm x 20cm x 5.2cm) at a submillimeter isotropic spatial resolution of 0.8mm.

3028. Dark Blood BSSFP Cardiac MRI Using HEFEWEIZEN

Karan Dara1, Jamal J. Derakhshan1, Jeffrey L. Duerk1, Jeffrey L. Sunshine2, Mark A. Griswold1

1Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States; 2Department of Radiology, University Hospitals of Cleveland, Cleveland, OH, United States

T2-weighted dark blood prepared TSE sequences are commonly used to image cardiac pathology. These methods often suffer from motion artifacts due to their long acquisition times. Here we apply a new, fast, high SNR, dark blood prepared segmented TrueFISP sequence (HEFEWEIZEN) for cardiac imaging in which some TR blocks are replaced by spatially selective saturation pulses for out-of-slice signals. This directionally suppresses bright blood flow (>65%) in the cardiac ventricles with some stationary tissue signal suppression offering a potential application to cardiac imaging.

3029. Banding Artifact Reduction in 2D CINE Balanced SSFP at 3.0 T Using Phase-Cycling and k-T BLAST

Ute Kremer1, Fabian Hezel2, Gabriele A. Krombach1, Thoralf Niendorf2,3

1Department of Diagnostic Radiology, University Hospital, RWTH Aachen, Aachen, Germany; 2Berlin Ultrahigh Field Facility, Max-Delbrueck Center for Molecular Medicine (MDC), Berlin, Germany; 3Charité, University Medicine, Berlin, Germany

This work proposes to combine phase-cycled bSSFP with k-t BLAST to overcome the scan time penalty of multiple-acquisition bSSFP while still eliminating off-resonance induced banding artifacts at 3.0 T. Acquisitions were conducted using four-fold accelerated k-t BLAST and three phase-cycles. For comparison conventional bSSFP was obtained and endocardial border sharpness (EBS) assessment was performed. In theory omitting one of the four standard phase-cycles disturbs the off-resonance profile's flatness, however for in vivo imaging it yielded excellent banding reduction and improved the mean EBS. Accelerated, phase-cycled bSSFP imaging promises to extend the capabilities of routine CINE imaging at (ultra)high fields.

Rare & Turbo Spin Echo

Hall B Wednesday 13:30-15:30

3030. Reduced SAR with Combined Acquisition Technique (CAT) Hybrid Imaging Sequence at 7 Tesla

Morwan Choli1, Felix A. Breuer1, Daniel Neumann2, Michael Bock3, Claudia M. Hillenbrand4, Ralf B. Loeffler4, Peter M. Jakob2,5

1Research Center Magnetic Resonance Bavaria e.V (MRB) , Wuerzburg, Germany; 2Dept. of Experimental Physiks 5, University of Würzburg, Wuerzburg, Germany; 3Department of Medical Physics in Radiology, , German Cancer Research Center (dkfz), Heidelberg, Germany; 4Department of Radiological Sciences, Division of Translational Imaging Research, Memphis, TN, United States; 5Research Center Magnetic Resonance Bavaria e.V (MRB), Wuerzburg, Germany

Higher field strength comes along with increase of the deposited SAR energy. Important imaging sequences like TSE with numerous refocusing pulses are only exercisable with limitations of the parameters at the expense of image quality to protect patients. In this work it is shown that it is possible to obtain high resolution in vivo images on a 7T scanner with an almost equal signal behavior in a combined acquisition technique (CAT) hybrid sequence consisting of a TSE module and an EPI module with SAR saving of 27%.

3031. "Spin-Echo Like T1 Contrast" Volumetric Black-Blood Images Using 3D LOWRAT: Low Refocusing Flip Angle TSE.

Masami Yoneyama1, Masanobu Nakamura1, Takashi Tabuchi1, Atsushi Takemura2, Junko Ogura1

1Medical Satellite Yaesu Clinic, Chuo-ku, Tokyo, Japan; 2Philips Electronics Japan, Ltd., Minato-ku, Tokyo, Japan

T1 weighted 3D VRFA-TSE sequence is decreasing flow artifacts by sequence-endogenous flow-void enhancement. But, T1 contrast becomes sub-optimal with the long echo train and pseudo steady-state effects. We propose a new scheme of more T1-optimized black-blood 3D TSE pulse sequence with low refocusing flip angles. Volunteer experiments were acquired in 3D low refocusing flip angle TSE (LOWRAT) using a 3.0T imager. The optimal parameter for T1-optimized black-blood imaging was low excitation flip angles, low refocusing flip angles, NPHA pseudo steady-state preparation, short ETL, best echo number for K-space center=2nd echo, and shortest TR. Contrast behavior of 3D LOWRAT T1W was similar to that of 2D SE. This optimal sequences can be used for 3D volumetric T1 weighted black-blood imaging.

3032. Rapid Optimization of Acquisition Parameters for Fast Spin Echo Imaging in RF Power Constrained Regimes

Robert Marc Lebel1, Alan W. Wilman1

1Biomedical Engineering, University of Alberta, Edmonton, Alberta, Canada

At high field strengths, fast spin echo is a SAR constrained procedure; parameter concessions are required to enable its use. Typical modifications include elongated RF pulses and reduced refocusing angles. We present an SNR analysis investigating the effects of reduced angles (lower signal) and longer RF pulses (less readout time) and present a reliable method for rapidly selecting these parameters to optimize the SNR for a given target power level.

3033. Reduced SAR with BASE Sequence at 7 Tesla

Daniel Neumann1, Morwan Choli2, Martin Blaimer2, Michael Bock3, Felix Breuer2, Peter M. Jakob4

1Experimental Physics 5, University of Würzburg, Würzburg, Germany; 2Experimental Physics 5, Research Center Magnetic Resonance Bavaria (MRB), Würzburg, Germany; 3Department of Medical Physics in Radiology, German Cancer Research Center (dkfz), Heidelberg, Germany; 4Experimental Physics 5, University of Würzburg, Würzburg, Bavaria, Germany

The step towards higher magnetic fields on the one hand provides a stronger NMR signal while on the other hand SAR is significantly increased in comparison with standard clinical scanners. Therefore the application of sequences using many refocusing pulses such as TSE can be difficult.

In this work we examine the potential of the BASE sequence to obtain high resolution images at 7T. BASE is a combination of BURST and multiple refocusing pulses. However, compared to TSE, there are a lower number of pulses and therefore SAR could be reduced by a factor of four.

3034. Whole-Brain FLAIR Using 3D TSE with Variable Flip Angle Readouts Optimized for 7 Tesla

John W. Grinstead1, Oliver Speck2, Dominik Paul, Lisa Silbert3, Louis Perkins3, William Rooney3

1Siemens Healthcare, Portland, OR, United States; 2Biomedical Magnetic Resonance, Otto-von-Guericke-University, Magdeburg, Germany; 3Oregon Health and Science University

Routine FLAIR uses a 2D inversion-recovery turbo spin echo pulse sequence having many high-SAR RF pulses, allowing only a few slices to be acquired at 7 Tesla. Recent work demonstrated the feasibility of using 3D IR-TSE with a T2-prepared IR and a reduced flip angle readout of 70 degrees to perform whole brain FLAIR at 7 Tesla for the first time. The present work extends this approach with a variable flip angle readout optimized for the T1 and T2 values of brain tissues at 7 Tesla to further improve the SAR, contrast, and SNR performance.

3035. Inversion of a Non-CPMG Fast Spin Echo Train.

Patrick H. Le Roux1

1Applied Science Lab, GE Healthcare, Palaiseau, IDF, France

The non-CPMG sequence permits to acquire MR signal in the Fast Spin Echo mode even when the CPMG (Carr Purcell Meiboom Gill) phase conditions cannot be fulfilled. It consists in a quadratic phase modulation of the refocusing pulses train, preceded by a suitable preparation period. It turns out that this sequence of RF pulses can be readily inversed permitting a perfect Driven Equilibrium scheme to be applied.

3036. Verse-Space

Guobin Li1, Christoph Sauerbier2, Dominik Paul3, Weijun Zhang1, Qiang He1, Marc Beckmann1, Lars Lauer3

1Siemens Mindit Magnetic Resonance Ltd., Shenzhen, Guang Dong, China; 2Hochschule Furtwangen University, Germany; 3Siemens Medical Solutions, Erlangen, Germany

Slab selection by the dual echo-spacing technique in SPACE with non-selective refocusing pulses needs averaging with phase cycling ans is sensitive to chemical shift artifacts during excitation. A new technique, VERSE-SPACE is presented in this abstract to provide faster acquisition speed and better slab profile than the previous technique.

3037. Multi-Slab SPACE

Guobin Li1, Dominik Paul2, Weijun Zhang1, Tallal Charles Mamisch3, Qiang He1, Marc Beckmann1, Lars Lauer2

1Siemens Mindit Magnetic Resonance Ltd., Shenzhen, Guang Dong, China; 2Siemens Medical Solutions, Erlangen, Germany; 3Department of Orthopaedic Surgery, Inselspital, University of Berne, Bern, Switzerland

In Single Slab SPACE, relative short TR and long echo train have to be used to reduce the total acquisition time into clinical acceptable range at the cost of the degradation in contrast purity and SNR, especially in PDw imaging. A new Multi-Slab SPACE is presented here to further increase the sampling efficiency, and then provides more flexibility to use longer TR and shorter echo train acquisition compared to Single Slab SPACE.

3038. Fast Spin-Echo Imaging of Inner Field-Of-Views Using 2D-Selective RF Excitations

Jürgen Finsterbusch1,2

1Department of Systems Neuroscience , University Medical Center Hamburg-Eppendorf, Hamburg, Germany; 2Neuroimage Nord, University Medical Centers Hamburg-Kiel-Lübeck, Hamburg-Kiel-Lübeck, Germany

Fast spin-echo imaging suffers from image blurring if a large number of echoes per excitation (turbo factor) is used and, in particular at higher magnetic fields, from SAR limitations. Focussing the field-of-view to a small inner volume reduces the number of required echoes considerably and thus ameliorates blurring and RF deposition. This is demonstrated in phantoms and the human brain at 3T using blipped-planar 2D-selective RF excitations. Thereby, the unwanted side excitations were positioned in the dead corner between the slice stack and the image section in order to minimize the duration of the 2DRF excitations without saturating neighbored sections.

Echo Planar Imaging: New Acquisition Approaches

Hall B Thursday 13:30-15:30

3039. An Effective Method to Increase Temporal or Spatial Resolution in Interleaved Echo Planar Imaging

Thomas Sushil John1, Dwight George Nishimura2, John Mark Pauly2

1Electrical Engineering , Stanford University, Stanford, CA, United States; 2Electrical Engineering, Stanford University, Stanford, CA, United States

A common solution to correct for ghosting in interleaved echo planar imaging (EPI) is to employ echo time shifting (ETS). Although ETS corrects for ghosting in a robust, non-iterative, and automatic manner, it does so at the expense of increasing total scan time. In this work, a simple, yet effective scheme to increase the efficiency of ETS is proposed. Using the proposed technique, shorter scan times are possible when the in-plane resolution is fixed. Alternatively, the proposed scheme can acquire higher resolution images when total scan time is fixed.

3040. Non-Uniform Density EPI Acquisition Improves the SNR of Smoothed MR Images

Lars Kasper1,2, S. Johanna Vannesjö1, Maximimilian Häberlin1, Christoph Barmet1, Klaas Enno Stephan2,3, Klaas Paul Prüssmann1

1University and ETH Zurich, Institute for Biomedical Engineering, Zurich, Switzerland; 2Institute for Empirical Research in Economics, University of Zurich, Laboratory for Social and Neural Systems Research, Zurich, Switzerland; 3 Institute of Neurology, University College London, Wellcome Trust Centre for Neuroimaging, London, United Kingdom

Smoothing MR-images is a common preprocessing step in areas like functional MRI to improve signal as well as noise characteristics of the images and facilitate inter-subject comparison. We present how an EPI-acquisition scheme (1.5 mm resolution) whose density is specifically tailored to match an image smoothing kernel improves the SNR of the finally smoothed images. Furthermore, this shows the opportunity to assign differing spatial properties to signal and noise contributions within an MR image. Because these non-uniform trajectories differ from common MR gradient demands, we relied on actually measured trajectories for our reconstructions, using an NMR field monitoring setup.

3041. Reducing the Effective Point Spread Function in Echo Planar Imaging Through the Use of Partial Fourier Asymmetric Spin Echo Pulse Sequences

Andrew Scott Nencka1, Daniel L. Shefchik1, Eric S. Paulson2, Andrzej Jesmanowicz1, James S. Hyde1

1Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, United States; 2Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, WI, United States

Pulse sequences which acquire trains of echoes face an inherent limit in resolution due to intra-acquisition decay. In gradient echo sequences, often used in functional studies, T2* decay leads to an increased point spread function in the phase encoding direction due to the lower effective bandwidth in that direction during data acquisition. In this abstract, we illustrate that the desirable T2’ weighting associated with gradient echo sequences may be preserved with an asymmetric spin echo, and that acquisitions on the ascending edge of the spin echo yield point spread functions which are reduced in the phase encoding direction. This effect comes from the competing T2’ rephrasing and T2 decay leading up to the formation of the spin echo. Matching the effective echo time on the ascending and descending sides of the spin echo can yield varying image contrast in vivo due to true T2 decay, thereby affecting the perceived smoothness of the reconstructed image.

MRI Sequence Optimisation

Hall B Monday 14:00-16:00

3042. Optimized, Unequal Pulse Spacing in Multiple Echo Sequences Improves Refocusing in Magnetic Resonance

Warren S. Warren1, Rosa Tamara Branca2

1Chemistry/CMBI, Duke University, Durham, NC, United States; 2Chemistry, Duke University, Durham, NC, United States

A recent quantum computing paper analytically derived optimal pulse spacings for a multiple spin echo sequence which differ dramatically from the conventional, equal pulse spacing of a Carr-Purcell-Meiboom-Gill (CPMG) sequence. Here we show that this “UDD sequence” has advantages for MR of tissue, where diffusion in microstructured environments leads to fluctuating fields on a range of different timescales. Both in excised tissue and in a live mouse tumor model, optimal UDD sequences produce different contrast than do CPMG sequences, with substantial enhancements in most regions. This provides a new source of endogenous contrast and enhances sequences which are currently T2-limited.

3043. T2-Prepared Segmented 3D-Gradient-Echo as Alternative to T2-Weighted TSE for Fast High-Resolution Three-Dimensional Imaging

Jian Zhu1,2, Axel Bornstedt1, Vinzenz Hombach1, Alexander Oberhuber3, Genshan Ma2, Naifeng Liu2, Volker Rasche1

1Department of Internal Medicine II, University Hospital of Ulm, Ulm, Germany; 2Department of Cardiology, Zhongda Hospital, Southeast University, Nanjing, China; 3Department of Thorax and Vascular Surgery, University Hospital Ulm, Ulm

Spin-echo and multi-spin echo sequences are still the gold standard for generation of a T2 – weighted image contrast. A major drawback of this technique rises from the long repetition times required for achieving sufficient recovery of the longitudinal magnetization, which cause long acquisition times especially in high-resolution volumetric imaging. In this study, the use of a fast gradient echo sequence with T2 preparation is investigated for generating a T2 weighted image contrast similar to a multi-spin echo approach, but with an up to 8-fold reduction of the acquisition time.

3044. Differential Subsampling with Cartesian Ordering (DISCO): A Novel K-Space Ordering Scheme for

Dynamic MRI

Dan Rettmann1, Manojkumar Saranathan1, James Glockner2

1Applied Science Lab, GE Healthcare, Rochester, MN, United States; 2Radiology, Mayo Clinic, Rochester, MN, United States

Dynamic contrast enhanced MRI (DCEMRI) and MR angiography (MRA) are both beset by the conflicting requirements of spatial and temporal resolution. Various schemes have been proposed and evaluated for high spatio-temporal resolution MR imaging which incorporate combinations of partial Fourier imaging, sub-sampling, view sharing and parallel imaging to effect acceleration. We propose DISCO (DIfferential Subsampling with Cartesian Ordering), a flexible k-space segmentation scheme that minimizes sensitivity to eddy currents and motion for dynamic imaging while dispersing artifacts and residual ghosting and demonstrate its use in first pass contrast enhanced liver imaging.

Motion Correction

Hall B Tuesday 13:30-15:30

3045. Advancements in Contact-Free Respiration Monitoring Using RF Pick-Up Coils

Ingmar Graesslin1, Giel Mens2, Alexander Guillaume1, Henry Stahl3, Peter Koken1, Peter Vernickel1, Paul Harvey2, Jouke Smink2, Kay Nehrke1, Peter Boernert1

1Philips Research Europe, Hamburg, Germany; 2Philips Healthcare, Best, Netherlands; 3FH Westküste, Heide, Germany

Advanced methods of motion detection and motion artifact reduction help to improve diagnostic image quality. The use of conventional navigators requires additional planning and adversely influences the steady state, which can result in image artifacts. A new approach was presented that uses the detection of changes of RF coil loading induced by the respiratory motion of the patient. This paper describes the application of a real-time self-navigated respiration monitoring approach using dedicated RF monitoring pulses instead the RF excitations of the imaging sequence. RF amplifier drift is analyzed, and a compensation scheme is proposed to overcome this problem.

3046. 3D TOF Angiography Using Real Time Optical Motion Correction with a Geometric Encoded Marker

Daniel Kopeinigg1,2, Murat Aksoy1, Christoph Forman3, Roland Bammer1

1Department of Radiology, Stanford University, Palo Alto, CA, United States; 2Institute of Medical Engineering, University of Technology Graz, Graz, Austria; 3Pattern Recognition Lab, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany

Correction of motion artifacts is an ongoing and very important task in MRI. This motion, most often introduced by patients that suffer from a medical condition, which makes it difficult to remain motionless during MRI acquisitions, can significantly corrupt the resulting images and their diagnostic value. In this study we show first in-vivo results of our prospective optical motion correction system applied to three-dimensional time of flight (3D TOF) angiography. Results show that compared to the non-motion corrected case the real-time motion correction is able to dramatically improve image quality of 3D TOF angiograms.

3047. Motion Characterisation Using FID Navigators and Spatial Pattern of MRI Coil Arrays

Tobias Kober1,2, José P. Marques1,3, Rolf Gruetter1,4, Gunnar Krueger2

1Laboratory for functional and metabolic imaging, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland; 2Advanced Clinical Imaging Technology, Siemens Suisse SA - CIBM, Lausanne, Switzerland; 3Department of Radiology, University of Lausanne, Lausanne, Switzerland; 4Departments of Radiology, Universities of Lausanne and Geneva, Switzerland

In this work we investigate the potential to characterise rigid-body head motion by monitoring free induction decay (FID) changes over time in coil arrays. The technique makes use of the fact that FID signals detected by local coil elements change as a function of object distance. Assuming a sufficient coverage of the scanned object with local coil elements, the inverse problem of back-calculation of the rigid motion parameters may be solvable. In this investigation, a framework to derive these motion parameters is developed and first results are shown from phantom and human scans using a 32-channel head coil array.

3048. Iterative Motion Compensated Reconstruction

Tim Nielsen1, Peter Boernert1

1Philips Research Europe, Hamburg, Germany

Motion during data acquisition can seriously degrade image quality. Motion compensated reconstruction can restore image quality if the motion is measured with suitable navigator signals. We present a new scheme for motion compensated reconstruction which can be applied to segmented Cartesian acquisitions (e.g. TSE, TFE). It can be combined with parallel imaging and is fast because it works mainly in the spatial domain avoiding many Fourier-transforms between k-space and image space. The motion is detected and quantified by adding an orbital navigator echo in front of the imaging echoes.

3049. On Motion Estimation and Compensation Baseline Estimations in Dynamic Imaging: A Comparative Study with Cine Cardiac and Contrast-Enhanced Lung Imaging

Mei-Lan Chu1, Jia-Shuo Hsu1, Hsiao-Wen Chung1

1Graduate Institute of Biomedical Electronics and Bioinformatics, National Taiwan University, Taipei, Taiwan

Estimation of the baseline is essential in compressed-sensing-based acceleration methods for MRI acquisition, as an accurate baseline estimation helps sparsifying the residues effectively. Recent literatures suggest improved baseline estimation using adaptive regularization or motion estimation (ME) and compensation (MC). While the suitability of these methods on other dynamic images with fast-varying contrast and morphology such as dynamic contrast-enhanced (DCE) lung imaging have not been investigated. Therefore, the purpose of this study is to explore the baseline estimation performance of the block-matching and the phase-correlation ME/MC on both cine cardiac and DCE lung imaging, in comparison with the conventional approach.

3050. Simple Self-Gating for Compensation of Respiratory Motion Using a Spiral K-Space Trajectory

Rafael Luis O'Halloran1, Murat Aksoy1, Tobias Kober2, Roland Bammer1

1Department of Radiology, Stanford University, Stanford, CA, United States; 2Laboratory for functional and metabolic imaging, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland

A simple method of respiratory monitoring using the phase of the DC term of k-space collected with a spiral k-space trajectory is presented and compared with the measurement from the respiratory bellows. The method presented is shown to be in excellent agreement with the measurement from the respiratory bellows and reveal even cardiac pulsatility. In this work the method is used to gate a spiral-trajectory scan of the liver. The image reconstructed with the DC phase used for gating was qualitatively similar to the one reconstructed using conventional gating. Since the image data is used for gating no additional navigators must be acquired.

3051. Methodology for Robust Motion Correction of Complex-Valued MRI Time Series

Andrew Hahn1, Daniel Rowe2

1Biophysics, Medical College of Wisconsin, Milwaukee, WI, United States; 2Mathematics, Statistics, and Computer Science, Marquette University, Milwaukee, WI

In functional MRI, subject motion during the acquisition of an image series can confound results and is generally corrected for using a variety of methods. Because statistical models for performing complex-valued fMRI analysis are available which can provide some benefits beyond the standard magnitude-only technique, investigation of a signal resulting from direct neuronal current involves complex-valued analysis, and recent reports have indicated potentially valuable functionally related phase signal, performing motion correction on complex-valued time series is of interest. This work identifies the problems facing motion correction of complex-valued images and proposes a solution for properly applying the correction.

3052. Compensation for Nonrigid Motion Using B-Spline Image Registration in Simultaneous MR-PET

Se Young Chun1, Sanghee Cho1, Tim G. Reese2, Bastien Guerin1, Xuping Zhu1, Jinsong Ouyang1, Ciprian Catana2, Georges El Fakhri1

1Division of Nuclear Medicine & Molecular Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, United States; 2Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, United States

This abstract reports preliminary results of motion corrected MR-PET reconstruction based on B-spline nonrigid image registration and compares it with HARP based motion compensation. With a breathing phantom, we collected MR and PET data simultaneously using BrainPET prototype PET scanner operating in the bore of a 3T TIM Trio scanner. Then we estimate the motion of a phantom using HARP and proposed B-spline based image registration with a novel invertibility penalty. These estimated motions were used in motion compensated iterative PET reconstruction. This preliminary result shows significant improvement of PET images for large motions.

3053. Respiratory Motion Correction of PET Using Simultaneously Acquired Tagged MRI

Timothy Gordon Reese1, Bastien Guérin2, Sanghee Cho2, Se Young Chun2, Jinsong Ouyang2, Xuping Zhu2, Ciprian Catana3, Georges El Fakhri2

1Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital , Boston , MA, United States; 2Division of Nuclear Medicine & Molecular Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, United States; 3Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Boston, MA, United States

As the spatial resolution of PET scanners improves, the deleterious effects of patient motion become an ever increasing limitation in PET studies. We present our first results with incorporating clinically relevant motion information derived from MR into the PET reconstruction process. We describe our current methods for tracking non-rigid periodic motion over the entire FOV of the MR-PET scanner, during the PET acquisition. All PET coincidences were reconstructed in a single frame while correcting the data for motion using MRI, demonstrating feasibility on an actual MR-PET system and a significant improvement in PET image quality.

3054. DCE-MRI Non-Rigid Kidney Registration

Michael Hofer1, Steven Keeling2, Gernot Reishofer3, Michael Riccabona4, Manuela Aschauer3, Rudolf Stollberger1

1Institute of Medical Engineering, Graz University of Technology, Graz, Austria; 2Institute for Mathematics and Scientific Computing, University of Graz, Graz, Austria; 3Department of Radiology, Medical University of Graz, Graz, Austria; 4Department of Pediatric Radiology, Medical University of Graz, Graz, Austria

Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) is a very promising method for noninvasive assessment of renal function. To remove the influence of motion artifacts like breathing, a novel registration approach is proposed which derives a template image series with the underlying signal time course. This results in an independency from signal changes due to contrast media uptake. The original dynamic time series (source images) is then registered by elastic registration to this virtual template. The algorithm successfully reduces motion artifacts. Comparisons between pre and post registration underlines the importance of image registration in DCE-MRI examinations.

3055. Flow Compensation in Frequency-Encode Direction for the Fast Spin Echo Triple-Echo Dixon (FTED) Sequence

Kaining Shi1,2, Russell Low3, Shanglian Bao1, Jingfei Ma2

1Beijing City Key Lab of Medical Physics and Engineering, Beijing University, Beijing, China; 2Imaging Physics, University of Texas MD Anderson Cancer Center, Houston, TX, United States; 3Sharp and Children's MRI Center, San Diego, CA, United States

The triple echo readout in the FTED sequence presents a challenge to achieve flow-compensation along the frequency-encode direction. In this work, two flow-compensation methods were proposed. In the first method, gradient moments are nulled at every RF locations so that the CPMG condition is always maintained. In the second method, the spin echo component of the signal is nulled at the 1st and 3rd echo locations and the stimulated component is minimized at different echo locations. The effectiveness of both methods in reducing the flow-induced artifacts was examined with a numerical calculation and demonstrated in a phantom testing.

3056. On the Optimization of Parallel Imaging for Ghost Reduction: A Blood Flow Example

Feng Huang1, Wei Lin1, Yu Li1, Arne Reykowski1

1Invivo Corporation, Gainesville, FL, United States

A parallel imaging based technique, COnvolution and Combination OperAtion (COCOA), has been proposed recently to efficiently remove ghost artifacts due to non-rigid motion. COCOA has two steps: a convolution step for a synthetic k-space with redistributed error, and a combination step for the final reconstructed k-space with reduced error. In this work, by using blood flow artifact as an example, the optimization schemes for these two steps are introduced to improve the ability for ghost suppression.

3057. Undersampled Reconstruction of Multiple 3D High-Resolution Respiratory Phases Using Non-Rigid Registration

Christian Buerger1, Andrew Peter King1, Tobias Schaeffter1, Claudia Prieto1

1Division of Imaging Sciences, King's College London, London, United Kingdom

A method for reconstructing multiple high-resolution respiratory phases from free-breathing 3D-MRI is presented. The proposed method combines an undersampled self-gating acquisition with a non-rigid image registration scheme. This approach uses all the acquired data to reconstruct a single high spatial resolution (HSR) phase at the most visited respiratory position and multiple respiratory resolved (RR) images at the remaining phases followed by an improving of image quality for all RR images (suffering from remained aliasing artifacts) using a registration procedure. This aligns the features of HSR with the remaining RR phases, leading to a sequence of time-resolved high resolution respiratory phases.

3058. MOtion Correction Using Coil Arrays (MOCCA)

Peng Hu1, Mehdi H. Moghari1, Beth Goddu1, Lois A. Goepfert1, Thomas H. Hauser1, Warren J. Manning1, Reza Nezafat1

1Beth Israel Deaconess Medical Center, Boston, MA, United States

We present a novel motion correction method using coil arrays (MOCCA). In MOCCA, the elements of a coil array are used as individual motion “sensors” which detect the motion-induced signal variations that are modulated by coil sensitivity maps. The inclusion of multiple coils by stacking multi-coil data into a column vector increased the accuracy of motion detection compared to existing methods based on projections. We evaluate the accuracy of MOCCA in a phantom and demonstrated the application of MOCCA on healthy volunteers for bulk motion correction in brain imaging and for respiratory and cardiac self-gating in cardiac cine imaging.

3059. Handling Motion in Sparse Reconstruction with Whiskers

Jason K. Mendes1, Dennis L. Parker1

1UCAIR, University of Utah, Salt Lake CIty, UT, United States

In general, the minimum number of K-Space samples required to produce good results in sparse reconstruction is approximately four times the number of sparse coefficients. Patient motion that is neither periodic nor smooth will reduce sparsity in the temporal direction and degrade the success of the sparse reconstruction. It is therefore beneficial to detect and correct as much patient motion as possible to maximize temporal sparsity and thus reduce the total number of K-Space samples required. This is accomplished using a hybrid Radial-Cartesian sampling technique called. This sequence has an inherent ability to correct bulk patient motion and is well suited to non-linear sparse reconstruction.

3060. Towards Lissajous Navigator-Based Motion Correction for MR-PET

Marcus G. Ullisch1,2, Tony Stöcker1, Kaveh Vahedipour1, Eberhard D. Pracht1, Lutz Tellmann1, Hans Herzog1, Nadim Jon Shah1,3

1Institute of Neuroscience and Medicine 4, Forschungszentrum Jülich GmbH, Jülich, Germany; 2Department for Psychiatry and Psychotherapy, RWTH Aachen University, Aachen, Germany; 3Faculty of Medicine, Department of Neurology, RWTH Aachen University, Aachen, Germany

With the combination of Magnetic Resonance Imaging (MRI) and Positron Emission Tomography (PET) into a single combined system, a novel imaging modality has become available. Previous approaches to patient motion tracking for PET data correction are difficult to use in the combined MR-PET environment. Thus, alternative methods for motion tracking have to be developed. Here, a novel approach for MR-PET motion correction utilising the Lissajous navigator is presented.

3061. 4D MAP Image Reconstruction of MRI Data

Jacob Hinkle1, Ganesh Adluru2, Edward DiBella2, Sarang Joshi1

1Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, UT, United States; 2Utah Center for Advanced Imaging Research, University of Utah, Salt Lake City, UT, United States

Conventional MRI reconstruction techniques are susceptible to artifacts when imaging moving organs. In this paper, a reconstruction algorithm is developed that accommodates motion instead of altering the scanning protocol. The maximum a posteriori (MAP) algorithm uses the raw time-stamped data to reconstruct the images and estimate deformations in anatomy simultaneously. The algorithm eliminates artifacts by avoiding gating processes and increases signal-to-noise ratio (SNR) by using all of the collected data. The algorithm is tested in a simulated torso phantom and is shown to increase image quality by dramatically reducing motion artifacts.

3062. Impact of Mechanical Vibration During DWI on Diffusion Parameter Estimation in Human Kidneys

Peter Vermathen1, Tobias Binser1, Chris Boesch1

1Dept. Clinical Research, University Bern, Bern, Switzerland

DWI leads to patient table vibration that may affect image quality, as has been demonstrated previously in phantoms and brain. We therefore investigated the impact of mechanical vibration during abdominal DWI on diffusion parameter estimation. Diffusion scans were performed on three subjects that were once in direct contact with the MR-system, thus experiencing vibration, and once without contact to the MR-System. The results demonstrate that the impact of vibration on diffusion parameter estimation, including micro-perfusion estimation, and also on the image intensity is only small. This holds true for standard measurement parameters.

3063. On the Application of TGRAPPA in Functional MRI

Hu Cheng1

1Indiana University, Bloomington, IN, United States

GRAPPA has been widely used in fMRI recently to improve spatial resolution. A drawback of GRAPPA for fMRI is that head motion in the reference scans can result in significant artifact for all the images in a run and higher temporal noise level. This problem can be solved by TGRAPPA using time interleaved sampling scheme. Separate reconstruction is needed for the interleaved k-space to minimize signal variation from volume to volume caused by phase errors. Although TGRAPPA has less statistical power than GRAPPA, the ability of retrospective motion correction makes it appealing in some application.

3064. Necessity of Sensitivity Profile Correction in Retrospective Motion Correction

Chaiya Luengviriya1,2, Jian Yun1, Kuan Lee3, Julian Maclaren3, Oliver Speck1

1Department of Biomedical Magnetic Resonance, Otto-von-Guericke University, Magdeburg, Germany; 2Department of Physics, Kasetsart University, Bangkok, Thailand; 3Department of Diagnostic Radiology, University Hospital Freiburg, Freiburg, Germany

Image artifacts induced by subject motion during multi-channel MRI were simulated for different sensitivity map profiles and different amounts of abrupt random motion. More localized maps resulted in stronger artifacts in the images. Two procedures for retrospective motion correction, k-space signal correction and sensitivity map correction were applied during an iterative non-Cartesian SENSE reconstruction. The signal correction evidently reduced the artifacts. The sensitivity map correction further improved image quality for strong motion and highly localized maps, at the cost of a longer computation time. For small motion and less localized maps, sensitivity map correction can be avoided since no improvement was visible.

3065. Dynamic Imaging Motion Artifact Reduction Using Adaptive K-Space Polynomial Interpolation

Travis B. Smith1, Krishna S. Nayak1

1Electrical Engineering, University of Southern California, Los Angeles, CA, United States

Any object movement during or between MRI acquisition readouts leads to data inconsistency artifacts in the images. The manifestation of these artifacts depends on the k-space sampling trajectory. For example, in echo-planar imaging they appear as “ghosting” artifacts, and in spiral imaging they manifest as “swirling” artifacts. Dynamic imaging, which attempts to capture body or physiological motion through continuous acquisitions, is vulnerable to these artifacts. In this work, we present an adaptive polynomial interpolation algorithm to reduce these artifacts without introducing significant motion blurring. In-vivo results are presented to compare the algorithm with other motion artifact reduction techniques.

3066. Magnitude-Weighted Phase Based Edge Detection for Navigator Gated Imaging

Kenichi Kanda1, Yuji Iwadate2, Yoshikazu Ikezaki1

1MR Engineering, GE Healthcare Japan, Hino, Tokyo, Japan; 2MR Applied Science Laboratory, GE Healthcare Japan, Hino, Tokyo

In navigator echo technique, accurate position detection of the diaphragm is essential. The edge detection analysis based on the phase profile of navigator enables the navigator gated imaging even with the saturation effect. However, the phase profile is sometimes unstable in the lung, and wrong position can be detected accordingly. We present a hybrid algorithm utilizing both magnitude and phase information to detect the diaphragm position. Our results show that the edge detection based on the magnitude-weighted phase data can detect the diaphragm position accurately even when the data have a fuzzy magnitude edge or noisy phase in the lung.

3067. Irretrievable Signal Loss in Partial-Fourier Acquired Diffusion-Weighted Images

Marcel Peter Zwiers1, Eelke Visser2, David Gordon Norris2, Nico Papinutto3, Benedikt Andreas Poser2

1Donders Institute for Brain, Cognition and Behaviour, Nijmegen, -, Netherlands; 2Donders Institute for Brain, Cognition and Behaviour, Nijmegen, Netherlands; 3Center for Mind-Brain Sciences, Trento, Italy

Diffusion weighted (DW) partial-Fourier (PF) imaging is highly sensitive to cardiac activity induced signal voids that depend critically on the image reconstruction method. The current explanation is that these artefacts result from incorrect phase estimation. We found that artefacts remained present in the PF acquired images, even when using zero-padding reconstruction or true (ideal) phase information. Cardiac pulsations induce phase gradients that can shift the local low-frequency information into the unacquired part of k-space. The associated signal voids are therefore irretrievable by any PF reconstruction method. Thus, PF DW imaging should generally be avoided or used solely with cardiac gating.

3068. Robust and Fast Evaluation of Orbital Navigator Data for Rigid Body Motion Estimation

Tim Nielsen1, Peter Boernert1

1Philips Research Europe, Hamburg, Germany

To overcome image artifacts induced by motion the use of navigator signals has been proposed, combined with either real-time correction of the data acquisition or motion compensated reconstruction. The quality of the correction depends critically on the estimated motion derived from the navigator signal. We present a fast, robust and precise algorithm to evaluate data from an orbital navigator trajectory and its application to motion compensated reconstruction.

3069. Direct and Independent Estimation of B0 Components Based on Raw EPI Data

Frederik Testud1, Iulius Dragonu1, Jürgen Hennig1, Maxim Zaitsev1

1Medical Physics, Department of Diagnostic Radiology, University Hospital Freiburg, Freiburg, Germany

GE EPI is a widely used imaging technique, but is very sensitive to B0 field inhomogeneities. To correct for temporal changes of B0, real-time measuring methods are necessary, such as estimating gradient maps of B0 from raw EPI data. Here a filter scheme is presented to calculate local B0 gradients. The local gradient in the readout direction is estimated independently from the gradient in the phase encoding direction by finding the contour lines of the gradients. This method is compared with previously introduced raw data based techniques and shown to perform better or equally well.

3070. Rapid Retrospective Non-Rigid Motion Correction for Free-Breathing MRI

Yoshihiro Tomoda1, Yuji Iwadate2, Tetsuji Tsukamoto2, Yoshikazu Ikezaki1

1MR Engineering, GE Healthcare Japan, Hino, Tokyo, Japan; 2MR Applied Science Laboratory, GE Healthcare Japan, Hino, Tokyo, Japan

We proposed a new framework that enables not only non-rigid motion correction with 100% acceptance rate but also rapid reconstruction. As the first investigation, we implemented the 1D non-rigid motion correction, called 1D MMFK, and confirmed the effectiveness with the simple linear expansion model by numerical simulation and volunteer scan.

3071. Correction of Motion Artifacts Using a Genetic Algorithm

Stephan Witoszynskyj1, Alexander Rauscher2

1Department of Radiology , Medical University of Vienna, Vienna, Austria; 2UBC MRI Research Centre, University of British Columbia, Vancouver, BC, Canada

We present a genetic algorithm for correction of motion artifacts in MRI. Two types of genetic algorithms were investigated: the first used only "non-sexual" multiplication and the second allowed "cross-over" between solutions. The algorithm corrects for translations by estimating correction factors for each k-space line. Four different image metrics were studied: entropy, normalized-gradient-squared (NGS), signal in the background and local coherence in the background. The best results were obtained by using the simple algorithm and NGS and entropy as metric. Since genetic algorithms are inherently parallelizable our approach could benefit greatly from being implemented on computer clusters and GPUs.

3072. Less Can Be More: Reduction of Motion Artifacts by Ignoring Parts of the Acquired Dataset

Tim Nielsen1, Jinnan Wang2,3, Peter Boernert1

1Philips Research Europe, Hamburg, Germany; 2Philips Research North America, Briarcliff Manor, NY, United States; 3University of Washington, Seattle, WA, United States

High resolution MR imaging of the carotids is an interesting technique for plaque characterization but image quality can be compromised by motion artifacts. Effects of breathing and pulsation can be reduced by gated acquisition. Coping with non-periodic motion (e.g. swallowing) is still often challenging in clinical practice and is considered as a major factor that contributes to the overall 20% failure rate in clinical scans. We present a method to reduce the effects of sudden, non-periodic motion by exploiting data redundancy which is usually present in parallel imaging with multiple receive coils. The method can be applied retrospectively without any navigator information.

3073. Fast Phase Based Registration for Robust Quantitative MRI

Anders Eklund1,2, Marcel Warntjes, 2,3, Mats Andersson1,2, Hans Knutsson1,2

1Division of Medical Informatics, Department of Biomedical Engineering, Linköping University, Sweden; 2Center for Medical Image Science And Visualization (CMIV), Linköping University, Sweden; 3Division of Clinical Physiology, Department of Medicine and Health, Linköping University, Sweden

Quantitative magnetic resonance imaging has the major advantage that it handles absolute measurements of physical parameters. Quantitative MRI

can for example be used to estimate the amount of different tissue types in the brain, but other applications are possible. When quantitative MRI is performed, a number of volumes are collected from the MR scanner. In order for the tissue quantification to work properly, the volumes have to be perfectly aligned. The problem with the volumes is that they differ significantly in intensity. We present a method for fast registration of such volumes and prove that it is more robust than the statistical parametric mapping (SPM) software.

3074. Navigator-Based Elliptical K-Space Reordering for Aortic 4D-Flow Imaging

Ashley Gould Anderson III1, Sebastian Gruhlke2, Oliver Wieben1,3, Michael Markl2,4

1Medical Physics, University of Wisconsin, Madison, WI, United States; 2Medical Physics, University Hospital Freiburg, Freiburg, Germany; 3Radiology, University of Wisconsin, Madison, WI, United States; 4Diagnostic Radiology, University Hospital Freiburg, Freiburg, Germany

Respiratory motion causes significant artifacts during 4D-Flow imaging in the torso due to long scan time requirements. Respiratory gating based on navigator signals or external measurements with bellows have been shown to reduce phase-related motion artifacts in long two- and three-dimensional free breathing acquisitions. Moreover, real-time adaptive k-space reordering, i.e. phase encoding based on the current position in the respiration cycle, can considerably improve navigator efficiency and thus reduce overall scan time. This work builds on proven respiratory gating and compensation methods by extending them to include reordering in the 3D slice-select direction in addition to the phase-encoding direction.

3075. Background Phase Correction Using K-Space Filters in Phase Contrast Velocity Encoded MRI

Martin Uppman1, Michael Markl2, Bruce S. Spottiswoode3,4

1Lund Institute of Technology, Lund, Sweden; 2Diagnostic Radiology, Medical Physics, Albert-Ludwigs Universität, Freiburg, Germany; 3MRC/UCT Medical Imaging Research Unit, Department of Human Biology, University of Cape Town, South Africa; 4Department of Radiology, Stellenbosch University, South Africa

This work evaluates k-space high-pass filtering as a post-processing background phase correction technique for 2D phase contrast velocity encoded MRI. Results are compared to an established technique which involves estimating the phase variation in stationary tissue and subtracting a fitted polynomial surface. Phantom and in-vivo studies show that k-space filtering with a large kernel performs equally as well as a high order polynomial surface subtraction.

3076. Intrinsic Detection of Corrupted Data

Jason K. Mendes1, Dennis L. Parker1

1UCAIR, University of Utah, Salt Lake CIty, UT, United States

Correlations between adjacent K-Space lines can be used to detect non-rigid body motion or motion that occurs out of plane. The cross correlation between two adjacent sets of equally spaced K-Space lines is a set of equally spaced delta functions convolved with an error function. The error function is a result of correlation errors between adjacent sets of lines. These errors are present even when there is no motion of any kind, however, as the amount of data corruption increases the error function broadens. As a result, a measure of the relative sharpness of the error function provides a measure of data corruption.

3077. SPI Motion Correction Using In-Plane Estimates

Ryan Keith Robison1, Kenneth Otho Johnson1, James Grant Pipe1

1Keller Center for Imaging Innovation, Barrow Neurological Institute, Phoenix, AZ, United States

Spiral Projection Imaging (SPI) allows for intrinsic estimation of rigid-body patient motion through the comparison of data between spiral planes that correspond to different time points but similar k-space locations. The in-plane estimation scheme produces 2D estimates of motion for each spiral plane. Full 3D motion estimates can be obtained for each plane by combining the 2D estimates of spatially orthogonal, sequential triplets of spiral planes. In-vivo images and quantitative estimation results are presented for simulated and in-vivo motion affected data.

3078. Reconstruction Exploiting Phase-Correlation Motion Estimation and Motion Compensation Methods for Cine Cardiac Imaging

Mei-Lan Chu1, Jia-Shuo Hsu1, Hsiao-Wen Chung1

1Graduate Institute of Biomedical Electronics and Bioinformatics, National Taiwan University, Taipei, Taiwan

Motion estimation (ME) and motion compensation (MC) are successfully exploited by dynamic MRI as baseline estimation for enhancing reconstruction. However, ME and MC have not been exploited as a standalone approach for direct dynamic MRI reconstruction, since the absence of full-resolution frames. A robust reconstruction technique was proposed in this work to address this issue, based solely on phase-correlation ME and MC methods without incorporating extra reconstruction routine. Cine cardiac images are tested with the proposed method, and the results indicate that the proposed method can achieve improved temporal resolution even from substantially down-sampled k-space data.

Image Correction: Gradients & Frequency

Hall B Wednesday 13:30-15:30

3079. Compressive Slice Encoding for Metal Artifact Correction

Wenmiao Lu1, Kim Butts Pauly2, Garry Evan Gold2, John Mark Pauly3, Brian Andrew Hargreaves2

1Electrical & Electronic Engr., Nanyang Tech. University, Singapore, Singapore; 2Radiology, Stanford University, Stanford, CA, United States; 3Electrical Engr., Stanford University, Stanford, CA, United States

Metal artifacts in MRI can be completely corrected by Slice Encoding for Metal Artifact Correction (SEMAC), which nonetheless incurs prolonged scan times due to the additional phase encoding along slice-select direction. Here we incorporate SEMAC with compressed sensing to vastly reduce the number of phase encoding steps required to resolve metal artifacts. The new technique, referred to as Compressive SEMAC, can greatly reduce scan times, while producing high-quality distortion correction and SNR comparable to SEMAC with full sampling.

3080. Noise Reduction in Slice Encoding for Metal Artifact Correction Using Singular Value Decomposition

Wenmiao Lu1, Kim Butts Pauly2, Garry Evan Gold2, John Mark Pauly3, Brian Andrew Hargreaves2

1Electrical & Electronic Engr., Nanyang Tech. University, Singapore, Singapore; 2Radiology, Stanford University, Stanford, CA, United States; 3Electrical Engr., Stanford University, Stanford, CA, United States

To obtain distortion-free MR images near metallic implants, SEMAC (slice encoding for metal artifact correction) resolves metal artifacts with additional z-phase encoding, and corrects metal artifacts by combining multiple SEMAC-encoded slices. However, many of the resolved voxels contain only noise rather than signals, which degrades signal-to-noise ratio (SNR) in the corrected images. Here the SEMAC reconstruction is modified to perform denoising using singular value decomposition, which exploits the redundancy in the SEMAC-encoded data received from multiple coils. We demonstrate the efficacy of the proposed technique in several important imaging scenarios where SEMAC-corrected images are liable to relatively low SNR.

3081. Imaging Near Metals with Phase Cycled SSFP

Michael Nicholas Hoff1, Jordin D. Green2, Qing-San Xiang1,3

1Department of Physics & Astronomy, University of British Columbia, Vancouver, British Columbia, Canada; 2Siemens Healthcare, Calgary, Alberta, Canada; 3Department of Radiology, University of British Columbia, Vancouver, British Columbia, Canada

A fast bSSFP technique is devised for removing imaging artifacts near metals. 3D phase cycled TrueFISP provides comprehensive artifact reduction using powerful gradients, two dimensions of phase encoding, short TR, and thorough refocusing of magnetization. Problematic banding artifacts are eliminated using a technique which formulates expressions for each voxel’s modulated magnetization, and then analytically solves the system with a simple Cross-Solution (XS) to obtain the demodulated magnetization. Application to a phantom consisting of a hip prosthesis within a Lego structure confirms that 3D imaging with XS-SSFP is simple, efficient, and robust in artifact reduction.

3082. B1 Effects When Imaging Near Metal Implants at 3T

Kevin M. Koch1, Kevin F. King1, Graeme C. McKinnon1

1Applied Science Laboratory, GE Healthcare, Waukesha, WI, United States

Recently developed techniques have enabled low susceptibility-artifact imaging near metal implants using conventional spin-echo acquisition strategies. Previous demonstrations of these techniques have been presented at 1.5T. While the susceptibility artifact mitigation of these techniques remains sufficient at 3T, here we address the effects of reduced B1 wavelength applied at 3T. These effects introduce increased B1 artifacts near metal implants, particularly those with long axes oriented collinear with B0. Finite element simulations and phantom images are presented to demonstrate and discuss these effects.

3083. Adaptive Slice Encoding for Metal Artifact Correction

Brian A. Hargreaves1, Garry E. Gold1, John M. Pauly2, Kim Butts Pauly1

1Radiology, Stanford University, Stanford, CA, United States; 2Electrical Engineering, Stanford University, Stanford, CA, United States

Slice encoding for metal artifact correction (SEMAC) excites 2D slices, then uses a 3D encoding to resolve the distortion of slices due to large metal-induced susceptibility shifts. The addition of a simple, fast spectral prescan easily estimates the extent of this distortion, allowing the slab width and encoded field-of-view to be adapted to the subject. This, allows the total number of excited slices to be greatly reduced without diminishing final image quality, thus offering a substantial reduction in SEMAC scan time.

3084. Fat-Suppressed and Distortion-Corrected MRI Near Metallic Implants

Brian A. Hargreaves1, Wenmiao Lu2, Kim Butts Pauly1, John M. Pauly3, Garry E. Gold1

1Radiology, Stanford University, Stanford, CA, United States; 2Electrical & Electronic Engineering, Nanyang Tech University, Singapore, Singapore; 3Electrical Engineering, Stanford University, Stanford, CA, United States

Fluid-sensitive volumetric imaging of patients with metallic implants is potentially an important diagnostic tool to assess for infection, implant loosening, or other complications. Recent MR techniques use spin echoes combined with additional encoding to substantially reduce distortion and signal loss artifacts. Here we demonstrate the use of these sequences with short TI inversion recovery (STIR) to provide reliable fat suppression near metallic implants, which is particularly important in assessment of many disorders.

3085. Spiral Chemical Shift Imaging in the Presence of Metal Artifacts

Atsushi M. Takahashi1

1Applied Science Laboratory, GE Healthcare, Menlo Park, CA, United States

MRI in the presense of metal in the body is complicated by B0 field perturbations and by the shortening of the T2* relaxation times. With a multi-interleave, short readout, spiral k-space trajectory, chemical shift imaging method, we can image in the presence of metal. Here we describe a method which can be used in-vitro to visualize the field maps surrounding metal implants.

3086. Evaluation of MR Image Artifacts of Stent Implants at 3 Tesla Using a Phantom Filled with Mineral Oil Compared to CuSO4

A Koenig1,2, Frank Reintke2, Gerrit Schönwald, 2,3, Gregor Schaefers2

1University of applied Science Gelsenkirchen, Gelsenkirchen, NRW, Germany; 2MR Safety Testing Laboratory, MR:comp GmbH, Gelsenkirchen, Germany; 3University Witten/Herdecke

The ASTM-Standard F2119-07 is used to evaluate artifacts of implants. According to the test method a phantom with CuSO4 is used. By replacing the solution by mineral oil it is desired to avoid standing waves in images. We tested both fluids in two sequences (SE/GRE) with 2 test devices, a Nitinol stent and an acryl reference tube. We compared a visual, a statistically and a manual analysis. We noticed non-significant results with one exception. Under certain conditions the standard CuSO4 can be exchanged with mineral oil allowing better and precise artifact analysis at higher field strengths ¡Ý 3 T.

3087. Comparison of Fat Suppression Methods for Functional and Diffusion Studies Using SE EPI at 7T

Dimo Ivanov1, Markus Streicher1, Andreas Schäfer1, Robert Turner1

1Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany

The increased SNR of ultra-high-field MR scanners allows high resolution functional and diffusion studies to be performed. Because chemical-shift artifact suppression is essential for SE EPI images, we evaluated the performance of different fat suppression techniques. Conventional methods using additional radiofrequency (RF) and gradient pulses provide suboptimal results owing to increased B0 and B1 inhomogeneity at higher fields. They also increase RF power deposition. A recently developed method using different slice-select gradient strengths during the excitation and refocussing pulses was demonstrated to be most robust, and delivered best chemical shift selection.

3088. Dynamic Frequency Drift Correction for Binomial Water Excitation

Dehe Weng1,2, Feng Xiu3, Xiaodong Zhou1,4, Qiang He1,4

1Siemens Mindit Magnetic Resonance Ltd, Shenzhen, Guangdong, China; 2Beijing MRI Center for Brain Research, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China; 3Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen, Guangdong, China; 4Life Science and Technology School, Tongji University, Shanghai, China

Binomial water excitation is useful in low field MR system (0.05 and a true positive rate of 91.8%.

3119. Automatic Segmentation of MR Images for Long-Bone Cross-Sectional Image Analysis

Shing Chun Benny Lam1, Hamidreza Salilgheh Rad1, Jeremy Magland1, Felix W. Wehrli1

1Radiology, University of Pennsylvania, Philadelphia, PA, United States

A software program has been developed to automatically segment cortical bone region from cross-sectional MR image of long bones such as the tibial shaft and extract geometric and parametric information from the segmented region. Our results show that the parameters obtained from the automatic segmentation software are in good agreement with those obtained from manual segmentation. With these parameters, the mechanical properties of the cortical bone can be quantified and analyzed over subject groups at different stages.

3120. Assessing the Accuracy of Detecting Mouse Brain Structure Changes from MRI Using Simulated Deformations

Matthijs Christiaan van Eede1, R Mark Henkelman1, Jason P. Lerch1

1Mouse Imaging Centre, Toronto, Ontario, Canada

The use of image registration to investigate shape differences in mouse brain MRIs have become a significant area of interest. It is unknown how accurately structural changes can be detected or whether this sensitivity varies with structure shape. We present a novel method to simulate deformation fields with known structural tissue change and subsequently attempt to recover the induced changes in 21 structures. We demonstrate that image based registration algorithms can reliably detect structural shape differences down to 5% in the structures with a lower surface to volume ratio, and reliably down to 10% in all others.

3121. Rapid Semi-Automatic Segmentation of the Spinal Cord from Magnetic Resonance Images

Mark Andrew Horsfield1, Stefania Sala2, Mohit Neema3, Martin Absinta2, Anshika Bakshi3, Maria Pia Sormani4, Mara Rocca2, Rohit Bakshi3, Massimo Filippi2

1Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom; 2Neuroimaging Research Unit, Ospedale San Raffaele, Milan, Italy; 3Laboratory for Neuroimaging Research, Harvard Medical School, Boston, MA, United States; 4Department of Health Sciences (DISSAL), University of Genoa, Genoa, Italy

A new semi-automatic method for rapid segmentation of the spinal cord from MR images is presented, based on an active surface (AS) model of the cord surface with intrinsic smoothness constraints. The intra- and inter-observer reproducibilities of cord area measures were evaluated, and compared favorably with an existing cord segmentation method. Correlations between cord area and clinical disability scores confirmed the relevance of the new method in measuring cord atrophy. A novel form of cord visualization is shown, in which the straightened cord center-line forms one coordinate axis of a new image, allowing simple visualization of the cord structure.

3122. Semi-Automated Microbleed Identification on Susceptibility Weighted Images

Samuel Barnes1,2, E. Mark Haacke1

1Wayne State University, Detroit, MI, United States; 2Loma Linda University, Loma Linda, CA, United States

A method to detect microbleeds in the brain in a semi-automated fashion is presented. The goal of this technique is to reduce the processing time of quantifying microbleeds. The semi-automated method compares favorably with manual counting achieving approximately 80% sensitivity and 100% specificity while reducing processing time to under an hour.

3123. Segmentation and Volume Estimation on a Sub-Voxel Basis Using Quantitative MR: A Validation Study

Janne West1,2, Jan B. Warntjes, 23, Peter Lundberg1

1Department of Medical and Health Sciences, Division of Radiation Physics, Linköping, Östergötland, Sweden; 2Center for Medical Imaging Science and Visualization, Linköping, Östergötland, Sweden; 3Department of Medicine and Health, Division of Clinical Physiology, Linköping, Östergötland, Sweden

Using an MR quantification sequence; specific brain-tissues typically exhibit a narrow range of R1, R2 and PD values, and thus the tissues in the brain can be identified as clusters in the three dimensional R1-R2-PD space. In partial volume voxels (voxels containing two or more tissue types) the R1-R2-PD values are a combination of the values from the contributing tissues. By using a partial volume model a segmentation method to assess fractional brain-tissue volumes of white matter (WM), grey matter (GM) and CSF for the complete brain on a sub-voxel basis was created and validated on 7 normal subjects.

3124. Brain Extraction Algorithm Using 3D Level Set and Refinement

Jinyoung Hwang1, HyunWook Park1

1Department of Electrical Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Korea, Republic of

Skull-stripping methods have been proposed widely, but they usually provide coarse segmentation results. For example, in superior and inferior slices, their results could serve incorrect result. Thus, we present a brain extraction algorithm using 3D level set and refinement process. First, 3D level set function is applied to whole brain volume, to find coarse brain region. The refinement process is then applied to the result of 3D level set function, which improves the accuracy of the final segmentation results. We evaluated the proposed method to normal brain data acquired from BrainWeb, IBSR, 1.5T, and 3T data.

3125. Symmetric and Multi-Scale Features for Automatic Segmentation of Multiple Sclerosis Lesions Using Pattern Classification

Marco Battaglini1, Nicola De Stefano1, Mark Jenkinson2

1Quantitative Neuroimaging Laboratory, University of Siena, Siena, Italy; 2Clinical Neurology, FMRIB Centre, University of Oxford, Oxford, Oxon, United Kingdom

IIn order to develop a fully automated segmentation tool for MS lesions we explore using novel input features with two pattern classification methods (Neural Networks and Random Forests). Results show a statistically significant improvement in DICE by using the novel multi-scale and symmetry features with both classifiers. To be useful for clinical trials we use multi-centre real clinical data, segmented by different manual raters, which makes this challenging. Nonetheless, we still achieve DICE results consistent with state-of-the-art methods, without requiring costly pruning of the Neural Networks, complicated post-processing, or having to apply any exclusion criteria to the images.

3126. Development of Partial Volume Segmentation of Brain Tissue Based on Diffusion Tensor Imaging (DTI)

Seiji Kumazawa1, Takashi Yoshiura2, Hiroshi Honda2, Fukai Toyofuku1, Yoshiharu Higashida1

1Department of Health Sciences, Kyushu University, Fukuoka, Japan; 2Department of Clinical Radiology, Kyushu University, Fukuoka, Japan

To study the cortical/subcortical diffusivity in neurological diseases, brain tissue segmentation methods based on DTI data have been proposed. However, a partial volume effect might complicate the segmentation. We present a brain tissue segmentation method based on DTI data. The features of our method include the conducting of the segmentation in DTI space without any registration, and the estimation of the partial volume fractions of each tissue type within a voxel using a maximum a posteriori probability principle. The results of the digital phantom experiment and human DTI data demonstrate that our method was able to perform a reasonable segmentation for brain tissue on DTI data.

3127. Characterization of Local Field Disturbances Through Phase Derivative Mapping

Hendrik de Leeuw1, Mandy Conijn1, Peter R. Seevinck1, Jeroen Hendrikse2, Gerrit H. van de Maat1, Chris J.G. Bakker1

1Image Sciences Institute, Utrecht, Netherlands; 2Radiology, University Medical Center Utrecht, Utrecht, Netherlands

In MRI studies, magnitude images are often used as the only source of information. Especially in the presence of local field distortions, this might be considered suboptimal, since information on the local magnetic field is encoded in the signal phase. Studies that use signal dephasing only, do not allow discrimination between paramagnetic and diamagnetic disturbances, since signal dephasing is independent of the sign of the field. We will show, by analysis of microbleeds and calcifications in the brain, that by using the phase derivative, local field disturbances can be detected and analyzed in terms of positive or negative susceptibility deviations.

3128. Detection of Abnormal Human Brain Structure from MRI Using Symmetry Features

Chi-Hsuan Tsou1, Tun Jao1,2, Jiann-Shing Jeng3, Jyh-Horng Chen, 1,4

1Graduate Institute of Biomedical Electronics and Bioinformatics, National Taiwan University, Taipei, Taiwan; 2Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan; 3Stroke Center and Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan; 4Interdisciplinary MRI/MRS Lab, Department of Electrical Engineering, National Taiwan University, Taipei, Taiwan

Brain magnetic resonance images (MRI) is crucial in modern medical diagnoses. However, there is usually a time delay between images acquisition and interpretation of radiologists and/or doctors who prescribe the images, which may contribute to clinical exacerbation of the patients. In this preliminary study, we use symmetry index to discriminate between normal brain structures and intracranial pathologies, and to provide a foundation for images auto-alarm system in the future. Experimental results of the proposed algorithm on 24 MR images (11 pathological, 13 healthy), show that the symmetric index can help differentiate the normal and abnormal brain structures with promising performance.

3129. Automatic Detection of the Anterior and Posterior Commissures from T1-Weighted Images

Islem Rekik1,2, Linda Marrakchi-Kacem1,3, Jean-François Mangin1,3, Denis Le Bihan1,3, Cyril Poupon1,3, Fabrice Poupon1,3

1NeuroSpin, CEA, Saclay, France; 2ESIEE, Noisy-le-Grand, France; 3IFR49, Paris, France

Frame-based interventional MRI and multi-subject image analysis often rely on the manual selection of the Anterior Commissure (AC) and the Posterior Commissure (PC) that are used to define the standard referential of Talairach. We developed a fast and fully automatic identification of the AC and PC points from T1-weighted MR images, thus leading to an automation of the image processing step during the neurosurgery planning.

3130. Objective Assessment of T2-Based Liver Lesion Classifiers

Christian Graff1, Eric W. Clarkson2, Maria I. Altbach2

1Division of Imaging and Applied Math/OSEL/CDRH, U. S. Food and Drug Administration, Silver Spring, MD, United States; 2Department of Radiology, University of Arizona, Tucson, AZ, United States

Classification of lesions as benign or malignant is an important imaging task. In liver, transverse relaxation time (T2) can be used as a classifier. Recently a radial fast spin-echo technique has been developed to obtain T2 estimates within a single breath-hold during which under-sampled radial k-space lines are acquired. The degree of under-sampling in this technique motivated the development of various post-processing techniques that attempt to enforce prior information to compensate for data under-sampling. In this work we evaluate these proposed algorithms through the use of a receiver-operating-characteristic (ROC) based metric which directly measures the classification performance of each algorithm.

3131. Bladder Wall Extraction and Mapping for MR Cystography

Jerome Zhengrong Liang1,2, Chaijie Duan1, Xianfeng Gu2, Mark E. Wagshul1, Hongbin Zhu1, Yi Fan1, Hongbing Lu3

1Radiology, Stony Brook University, Stony Brook, NY, United States; 2Computer Science, Stony Brook University, Stony Brook, NY, United States; 3Biomedical Engineering, Fourth Military Medical University, Xian, China

MRI-based virtual cystoscopy, MR cystography, T1-weighted imaging, bladder cancer, tumor recurrence, image segmentation, conformal mapping, 3-D to 2-D flattening

3132. Effects of Treatment on Brain Tissue Classification with Serial MRI-Based ISODATA Cluster Analysis in an Experimental Subarachnoid Hemorrhage Model

Mark J.R.J. Bouts1, Ivo A.C.W. Tiebosch1, René Zwartbol1, Ona Wu2, Rick M. Dijkhuizen1

1Image Sciences Institute, University Medical Center Utrecht, Utrecht, Netherlands; 2Athinoula A. Martinos center for biomedical imaging, Massachusetts General Hospital, Charlestown, MA, United States

Voxel-wise clustering of multiparametric MRI data enables classification of heterogeneous ischemic lesions into distinct categories. Previously, we have introduced a lesion clustering approach that incorporates temporal T2 and diffusion dynamics for tissue characterization. In the current study we extend this approach in an experimental subarachnoid hemorrhage model, to evaluate lesion characteristics in a treatment and control group based on temporal changes in T2, diffusion, and perfusion parameters. Five distinct signatures with different characteristics of cerebrovascular injury were identified and signature distribution revealed a different prevalence in Interferon-β treated animals compared to controls.

3133. A Multi-Anatomy System for Computing and Centering Field of View from Localizer Images

Vivek Prabhakar Vaidya1, Maggie M. Fung2, Rakesh Mullick1, Robert D. Darrow3

1GE Global Research, Bangalore, Karnataka, India; 2GE Healthcare, Waukesha, WI, United States; 3GE Global Research, Niskayuna, NY, United States

A system is demonstrated for automatically deriving and centering oblique scan extents/fields of view (FOV) from localizer scans. Our method differs from prior work in the field by being marker-less and allowing for automated acquisitions oblique to the input localizer. By constraining acquisition to the precise extents of the anatomy being sought acquisition time is reduced. This acquisition time reduction is particularly valuable in cardiac and abdominal imaging: given the need for breath-held scanning. Furthermore, by prescribing an optimal field of view we can also reduce potential wrapping artifacts and improve the consistency of image representation.

3134. Automated Volume of Interest Evaluation for Sequence Development

Ying Wu1,2, Hongyan Du3, Fiona Malone1, Shawn Sidharthan1, Ann Ragin4, Robert Edelman1,5

1Radiology, NorthShore University HealthSystem, Evanston, IL, United States; 2Radiology , University of Chicago; 3NorthShore University HealthSystem Research Institute, IL, United States; 4Radiology, Northwestern University; 5Radiology, University of Chicago

This investigation compared the standard manual region of interest approach with a volume-of-interest analysis based on automated brain segmentation. Analysis based on automated VOI successfully detected subtle changes in tissue contrast and was consistently informative for MR sequence optimization. Results based on the standard ROI approach were ambiguous in different brain regions and individuals, and failed to document changes in image quality when scanning parameters were alternated in MR sequence optimization. These findings demonstrate the potential benefit of integrating advanced quantitative image analysis into sequence development routines to improve efficiency and accuracy.

Registration & Image Analysis

Hall B Wednesday 13:30-15:30

3135. Combining Variational and Model Based Techniques to Register MR Finger Images and PET Hand Data

Derek Magee1, Steven Frederick Tanner2, Michael Waller3, Ai-Lyn Tan4, Dennis McGonagle4, Alan Jeavons3

1School of Computing, University of Leeds, Leeds, W-Yorkshire, United Kingdom; 2Division of Medical Physics, University of Leeds, Leeds, W-Yorkshire, United Kingdom; 3Medical Physics, St James University Hospital, Leeds, United Kingdom; 4Academic Section of Musculoskelatal Disease, Chapel Allerton Hospital, Leeds, W-Yorkshire, United Kingdom

A non-rigid image registration method for co-registering high-resolution PET data and MR images of the hand is described and evaluated. Employing this protocol to register synthetic data indicated a the mean registration error of less than approximately 1.5 mm. Measurements made in images acquired from patients with osteoarthritis show that the registration errors are consistent with those made in the study using synthetic data.

3136. Automated Scan Plane Planning for Brain MRI Using 2D Scout Images

Suguru Yokosawa1, Yo Taniguchi1, Yoshitaka Bito1, Hisako Nagao2, Miki Tachibana2, Mutsumi Ishida2, Atsushi Shiromaru2, Hiroyuki Itagaki2

1Central Research Laboratory, Hitachi, Ltd., Kokubunji-shi, Tokyo, Japan; 2Hitachi Medical Corporation, Kashiwa-shi, Chiba, Japan

We propose a faster automated scan plane planning method for the brain using 2D multi-slice orthogonal three-plane scout images. Our algorithm based method, uses 2D scout images, which can be acquired rapidly. Furthermore, our algorithm can prescribe scan plane faster than other method that use 3D data due to the smaller 2D data size. We applied our proposed method to healthy volunteers, and compared automatically defined scan plane position with those manually defined. The results showed that our method prescribed scan planes quickly and with acceptable accuracy in clinical practice.

3137. Quantitative and Local Mouse Brain Morphometry in Longitudinal MRI Studies

Alize Elske Hiltje Scheenstra1, Dana Suciu2, Michael Muskulus3, Melly S. Oitzl4, Johan H.C. Reiber1, Louise van der Weerd5, Jouke Dijkstra1

1Radiology, image processing, LUMC, Leiden, Netherlands; 2Radiology, LUMC, Leiden, Netherlands; 3Mathematical Department, Leiden University, Leiden, Netherlands; 4LACDR, Leiden University, Netherlands; 5Department of Anatomy and Embryology, LUMC, Leiden, Netherlands

We present the Moore-Rayleigh (MR) test as nonparametric statistical test for longitudinal brain MRI deformation based morphometry: A group of male mice (n=10) was followed during exposure to the stress hormone hormone corticosterone for 2 weeks and a recovery period of 1 week. The results of the MR test are comparable to volumetric based morphometry, but it enriches the analysis with its ability to detect also localized shape changes, which are still significant under Bonferroni correction.

3138. Type I Errors in Whole Brain Voxel-Wise Analyses

David Matthew Carpenter1, Cheuk Ying Tang1,2

1Radiology, Mount Sinai School of Medicine, New York, United States; 2Psychiatry, Mount Sinai School of Medicine, New York, NY, United States

Voxel based analysis or Statistical Parametric Mapping (SPM) yields inconsistent results across studies. It is difficult to challenge the validity of SPM results in published works and review submissions because the nature of the immense datasets that underlie VBA results prohibits its presentation in journals. In this abstract we use a simple data set to explore sources of type I errors in areas that often yield positive results and present findings that can serve as a guide for critiquing these SPM presentations.

3139. Propagation-Based Morphometry in an Ex Vivo Mouse Embryo Atlas – Assessment and Validation

Francesca C. Norris1,2, Jon O. Cleary1,3, Marc Modat4, Anthony N. Price1, Karen McCue5, Sarah Beddow5, Peter J. Scambler5, Sebastien Ourselin4, Mark F. Lythgoe1

1Centre for Advanced Biomedical Imaging, Department of Medicine and UCL Institute of Child Health, University College London, London, United Kingdom; 2Centre for Mathematics and Physics in the Life Sciences and EXperimental Biology (CoMPLEX), University College London, London, United Kingdom; 3Department of Medical Physics and Bioengineering, University College London, London, England, United Kingdom; 4Centre for Medical Image Computing, University College London, London, United Kingdom; 5Molecular Medicine Unit, UCL Institute of Child Health, University College London, London, United Kingdom

The increasing use of genetically modified mice has highlighted the need for effective phenotyping methods. Propagation-based morphometry (PBM) is an emerging technique enabling non-invasive and rapid acquisition of volumetric data using an average population atlas for morphometric analysis. Thus, PBM shows promise for combining high-throughput µMR imaging of late-gestation embryos with high-throughput analysis. We present the first study to assess and validate the accuracy of volumes generated via PBM in an ex vivo mouse embryo atlas comprising three different groups. Preliminary results show promise towards the broad applicability of this technique for phenotyping mutant mouse models.

3140. A New Approach to Mouse Brain Mapping

Marianne Dorothea Keller1,2, Charles Watson3, Kay Richards4, Rachel Buckley5, Nyoman Kurniawan6, Richard Beare5, Jana Vukovic2, Deming Wang1, Steven Yang1, Peter Zhao7, Nathan Faggian4, George Paxinos7, Steven Petrou4, Gary Egan4, Perry Bartlett2, Graham Galloway1, David Reutens8

1Centre for Magnetic Resonance, University of Queensland, Brisbane, Qld, Australia; 2Queensland Brain Institute, University of Queensland, Brisbane, Qld, Australia; 3Curtin University, Perth, WA, Australia; 4Florey Neuroscience Institutes, Melbourne, Vic, Australia; 5Monash University, Melbourne, Vic, Australia; 6Centre for Magnetic Resonance, University of Queensland, Brisbane,, Qld, Australia; 7Prince of Wales Medical Research Institute, Sydney, NSW, Australia; 8Centre for Advanced Imaging, University of Queensland, Brisbane, Qld, Australia

When working with mouse brain models it becomes apparent, that anatomically detailed, three dimensional atlases are not readily available. On one hand, histological atlases are two dimensional, whereas three dimensional MRI atlases might only define 40 brain structures.

Our aim is to create an digital atlas using high resolution images produced by a 16.4 T MRI scanner, complemented by histological data. A higher grade of segmentation, for example 45 structures in the cerebellum and 35 in the hippocampus, will enable the researcher to compare normal mouse brain anatomy to pathological anatomical changes in models of disease.

3141. Developmental Changes in the Shape of Hippocampus in Children Aged from 6 to 9 Years Old

Muqing Lin1, Lutfi Tugan Muftuler1, Ke Nie1, Kevin Head1, Claudia Buss2, Elysia Poggi Davis2, Curt A. Sandman2, Orhan Nalcioglu1, Min-Ying Lydia Su1

1Tu & Yuen Center for Functional Onco-Imaging, University of California, Irvine, Irvine, CA, United States; 2Department of Psychiatry and Human Behavior, University of California, Irvine, Irvine, CA, United States

The shape analysis of hippocampus was commonly applied to evaluate the progression of atrophy pattern in elderly patients, and in this study it was applied to evaluate the changes in developmental brain in 48 children. The distance from the hippocampal surface to the central line was mapped to a 2D grid for statistical analysis. The Permutation and t-test was applied to compare two age groups (6-7 vs. 8-9 y/o), and the regression analysis with age was also performed. Significant differences were found in small areas of CA1 and subiculum; however, overall there is not a strong age dependence.

3142. Comparison of Normalized DTI Analytical Methods II: Detection Powers of Voxel-Based, Atlas Based, and Sub-Atlas Based Analysis

KOJI SAKAI1, Susumu Mori2, Kenichi Oishi2, Andreia Faria2, Naozo Sugimoto

1Kyoto University, Kyoto, Japan; 2Johns Hopkins University

The VBA is one of the most effectual assessment methods of the entire white matter of brain. However, the VBA often suffers from high false discovery rate which caused by embedded noise in voxels and imperfect registration. On the other hand, 3D whole brain WM atlas (ABA: atlas-based analysis) was proposed to achieve statistical power on the examination of the WM analysis. We also have proposed alternative way to analyse WM by sub-atlas based analysis (SBA). In this paper, we attempted to ascertain the statistical detection power and the features of VBA, ABA, and SBA.

3143. Accelerating the Image Registration of MRI Volumes by Modern GPGPU Parallel Computation

Shiun-Ying Ju1, Yu-Wei Tang1, Teng-Yi Huang1

1Department of Electrical Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan

Image registration has been an important topic in the MRI applications, such as longitudinal follow-up studies, brain-normalization for group statistics and motion correction for fMRI studies. However, the automatic registration requires a lot of iteration loops and a huge amount computation for linear transformations and thus it is generally very time-consuming task. In our study, we proposed to use the parallel computing on recently advanced general-purpose computation on graphic processing units (GPGPU) to accelerate the registration calculations, especially for the popular SPM system. We got about 23-fold acceleration of the computation process on our datasets.

3144. A Novel Parameterization-Invariant Riemannian Framework for Comparing Shapes of 3D Anatomical Structures

Sebastian Kurtek1, Eric Klassen2, Anuj Srivastava1, Zhaohua Ding3,4, Sandra W. Jacobson5, Joseph L. Jacobson5, Malcolm J. Avison3,4

1Department of Statistics, Florida State University, Tallahassee, FL, United States; 2Department of Mathematics, Florida State University, Tallahassee, FL, United States; 3Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States; 4Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, United States; 5Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, MI, United States

Shape analysis of anatomical structures is central to medical diagnosis, especially when using MRI data. We propose a novel Riemannian framework for analyzing shapes of 3D brain substructures (e.g. putamen). This framework provides metrics that are invariant to rigid motion, scaling and most importantly parameterizations of surfaces (placements of meshes). The metric is evaluated by a gradient-based alignment of meshes for the surfaces being compared. Consequently, the distance between identical surfaces with different meshes is zero. We present results of this methodology applied to comparisons of left putamens across subjects and to classification of subjects with prenatal exposure to alcohol.

3145. Construction of a Population Based Diffusion Tensor Image Atlas of the Sprague Dawley Rat Brain

Jelle Veraart1, Bjornar T. Antonsen2, Ines Blockx3, Wim Van Hecke4,5, Yi Jiang6, G. Allen Johnson6, Annemie Van Der Linden3, Trygve B. Leergaard2, Marleen Verhoye3, Jan Sijbers1

1Vision Lab, University of Antwerp, Antwerp, Belgium; 2Center for Molecular Biology and Neuroscience, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway; 3Bio Imaging Lab, University of Antwerp, Antwerp, Belgium; 4Department of Radiology, University Hospital Antwerp, Antwerp, Belgium; 5Department of Radiology, University Hospitals of the Catholic University of Leuven, Leuven, Belgium; 6Duke Center for In Vivo Microscopy, Duke University Medical Center, Durham, NC, United States

An anatomically labeled DTI atlas of the adult Sprague Dawley brain is proposed. The atlas is constructed using a population based atlas construction approach to create a template which represents the average anatomy. Further, a bias to a single subject is minimized. During the construction, a non-rigid coregistration technique is used to avoid local misalignment inaccuracies due to intersubject differences. The delineation of brain structures was performed on high resolution ex-vivo scans and the resulting parcellation maps were non-linearly warped into the in-vivo atlas space afterwards. The atlas is perfectly suited for automated ROI analysis and more standardized VBA studies.

3146. Comprehensive Digital 3D Monkey Brain MRI Atlas

Tina Jeon1, Takashi Yoshioka2, Steven Hsiao2, Stewart Hendry2, Hao Huang1

1Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX, United States; 2Mind and Brain Institute, Johns Hopkins University, Baltimore, MD, United States

Due to their close relationship to the human brain, animal models of primates have been unique and irreplaceable in neurobiological studies. In these studies, atlases have played central roles as anatomical references. However, few atlases are 3D, digital, or have comprehensive gray and white matter labeling. In this abstract, we show the digital atlas with complete labeling of cortical gyri, subcortical nuclei and white matter tracts with high resolution DTI. The digital format of the atlas makes it possible to map the labeling information of the atlas to the experimental monkey brain with image registration.

3147. Arterial Input Function Correction and Its Impact on Quantitative DCE-MRI: A Comparison with DCE-CT

Lauren Jean Bains1,2, Josephine H. Naish1,2, David L. Buckley3

1Imaging Science and Biomedical Engineering, School of Cancer and Imaging Sciences, University of Manchester, Manchester, Greater Manchester, United Kingdom; 2University of Manchester Biomedical Imaging Institute, University of Manchester, Manchester, Greater Manchester, United Kingdom; 3Division of Medical Physics, University of Leeds, Leeds, United Kingdom

Quantitative DCE-MRI benefits from the use of individual patient AIFs, however, accurate MRI-based AIF measurements are complicated by partial volume and inflow effects. We tested two methods of AIF correction based on cardiac output, and evaluated their effects on DCE-MRI tracer kinetic parameter estimates by comparing these estimates with DCE-CT, a modality which is unaffected by many of the artefacts that are problematic in DCE-MRI. Our results show that the use of cardiac output to correct DCE-MRI produces parameter estimates which are significantly closer to DCE-CT with reduced variance; the use of such corrections may significantly benefit DCE-MRI analyses.

3148. A Novel Method for Automatic Estimation of M0 Used by ASL CBF Quantification

Ognjen Zivojnovic1, Greg Zaharchuk2, Ajit Shankaranarayan3

1Stanford University, Stanford, CA, United States; 2Department of Radiology, Stanford University, Stanford, CA, United States; 3Applied Sciences Laboratory - West, GE Healthcare, Menlo Park, CA, United States

Calculating quantitative CBF values based on ASL images requires knowledge of M0. Two models exist for estimating its value, a blood based model that depends on the M0 of CSF, and a tissue based model that requires the re-imaging of the entire volume. This abstract presents a novel method for automatically estimating M0 based on the blood model in order to take advantage of its faster scan times compared to the tissue based model, as well as to remove human inconsistencies in selecting the area from which the estimate is made.

3149. Haemal Supplies Correlation Based Hepatic Nodules Identification from Dynamic Contrast-Enhanced MR Images

Min Sun1,2, Xuedong Yang3, Dongjiao Lv4, Mingyuan Xie2, Ling Yang2, Chengbo Wang5, Xiaoying Wang, 1,3, Jue Zhang, 1,4, Jing Fang, 1,4

1Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China; 2Dept. of Electronic Engineering, Chengdu University of Information Technology, Chengdu, Sichuan, China; 3Dept. of Radiology, Peking University First Hospital, Beijing, China; 4College of Engineering, Peking University, Beijing, China; 5Dept. of Radiology, University of Virginia, Charlottesville, Virigina, United States

Early detection of liver nodular lesions is critical in improving patient¡¯s survival rate. Previous studies have shown that for dynamic contrast-enhanced MR imaging of liver nodules, there exists correlation between nodules¡¯ blood supplies and MR signal changes. In this retrospective study, haemal supplies correlation based strategy was introduced to identify the suspected hepatic nodules, including DN, RN and SHCC from dynamic contrast-enhanced MR Images, and the analysis results were in consistence with the clinical diagnosis under double-blind test. The proposed computer aided identification approach could be helpful to provide valuable information for the detection of hepatic nodules.

3150. Performance and Accuracy of a Morphological MR Marker Localization at Reduced Spatial Resolutions: Results from Simulated and Real Marker Images

Gregor Thörmer1, Nikita Garnov1, Jürgen Haase2, Thomas Kahn1, Michael Moche1, Harald Busse1

1Diagnostic and Interventional Radiology, Leipzig University Hospital, Leipzig, Germany; 2Physics and Geosciences Department, Leipzig University, Leipzig, Germany

MR-visible markers have many potential applications such as an automated mapping of coordinate systems (image/patient registration), stereotactic planning/monitoring of procedures, and the localization/tracking of devices inside the magnet. In this work, precision, accuracy and update rates of a fully automatic marker localization based on morphologic image processing have been studied experimentally as well as theoretically (simulation) as a function of the underlying pixel size. The moderate 3D errors (¡Ö1 mm) observed for the fastest sequence (pixel dimension 4.7 mm) clearly demonstrate that the presented technique does not necessarily require highly resolved images of the markers (physical dimension ¡Ö4 mm).

3151. Automatic MRI Acquisition Parameters Optimization Using Perceptual Criteria

Javier Jacobsen1,2, Sergio Uribe, 2,3, Cristian Tejos1,2, Carlos Sing-Long1,2, Pablo Irarrazaval1,2

1Department of Electrical Engineering, Pontificia Universidad Catolica de Chile, Santiago, Chile; 2Biomedical Imaging Center, Pontificia Universidad Catolica de Chile, Santiago, Chile; 3Department of Radiology, Pontificia Universidad Catolica de Chile, Santiago, Chile

The visualization of structures in MRI highly depends on many user defined scan parameters. The selection of them is always done heuristically and requires a vast experience from the operator. We propose a methodology based on an automatic optimization to find the MRI acquisition parameters that maximize the visibility of a desired structure. The objective function of our optimization is computed from Visibility Maps (VM) that are designed to measure the visibility of structures according a perceptual criteria. The method was tested on brain MRI experiments and the optimal parameters found by our method are in excellent agreement with those found by experienced radiologists.

3152. A Stochastic Framework for Improving the Accuracy of PIESNO

Cheng Guan Koay1, Evren Ozarslan1, Carlo Pierpaoli1, Peter J. Basser1

1NIH, Bethesda, MD, United States

Probabilistic Identification and Estimation of Noise (PIESNO) is a recent technique capable of identifying noise-only pixels in magnitude-reconstructed MR images. The identification criterion and the estimation method used in PIESNO were chosen and constructed for expediency in terms of computational efficiency and theoretical simplicity rather than for accuracy. Although a strictly theoretical approach to determine the exact level of bias in the estimate of noise level through PIESNO seems to be intractable, it is still worthwhile to use stochastic framework for determining the level of bias. Here, we present one such framework for improving the accuracy of PIESNO.

3153. Comparison of SNR Calculation Methods for in Vivo Imaging

Bing Wu1, Chunsheng Wang1, Yong Pang1, Xiaoliang Zhang1,2

1Radiology&Biomedical Imaging, University of California, San Francisco, San Francisco, CA, United States; 2UCSF/UC Berkeley Joint Group Program in Bioengineering, CA, United States

Local and global SNR of in vivo MR images are often measured to evaluate the image quality. Due to the density variation of in vivo images, the motion during the acquisition and other aspects, the SNR measurement of the in vivo image, especially at high field MRI, is much more complicated. The purpose of this work is to evaluate and compare SNR calculation methods to provide the reference or guidance for in vivo image SNR measurements.

3154. Consistency Assessment for R2* Measurements Obtained with Different Techniques at 7 Tesla

Xiangyu Yang1, Petra Schmalbrock1, Michael V. Knopp1

1Department of Radiology, The Ohio State University, Columbus, OH, United States

At high and ultrahigh field, R2* measurement can be dependent on the technique used due to non-exponential FID distortions caused by various factors. In this study, we compared R2* measurements obtained with three different techniques in a group of four healthy volunteers at 7 Tesla to assess their consistency. Our results demonstrate that R2* values measured with a 2D imaging technique is only comparable with those from a 3D technique when appropriate correction for the background field inhomogeneity effect is applied.

3155. Analysis of Abdominal Fat Tissue Images Acquired with Continuously Moving Table MRI

Stathis Hadjidemetriou1, Juergen Hennig1, Florian Klausmann1, Ute Ludwig1

1Department of Diagnostic Radiology, University Hospital Freiburg, Freiburg, Germany

The risk for hypertension and diabetes is correlated closely to the amount of visceral fat. In this work, the abdominal fat is imaged with a continuously moving table whole body MRI technique. A method is presented for the repeatable, general, and reliable differentiation of lipids into subcutaneous and visceral. The data is restored for intensity uniformity. The corrected image is processed to segment the body region with the graph cuts algorithm operating on level sets. Then, the contour separating the subcutaneous and visceral fat regions is identified with a combination of the random walks algorithm and graph cuts.

3156. Fast Fat/Water Decomposition Using GPU Computation and Newton's Method

David Johnson1, Sreenath Narayan2, Chris Flask, 2,3, David Wilson2,3

1Heart and Lung Research Institute, Ohio State University, Columbus, OH, United States; 2Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States; 3Radiology, University Hospitals of Cleveland, Cleveland, OH, United States

An improved fat/water estimation technique was developed using Iterative Decomposition of Water and Fat with Echo Asymmetry and Least-squares estimation method and Graphics Computational Units (IDEAL-GPU). The IDEAL-GPU technique produced robust fat and water images quickly and efficiently using a vectorized equation implemented on graphics cards. In addition, our implementation used binary weighted planar extrapolation for robust estimation in the face of large field variations on a high field, small animal scanner. Fast computation will become even more significant as the trend towards high resolution, whole body mouse and human scanning continues.

3157. Case-PDM Optimized Compressed Sensing Sampling for Fat-Water Separation

Sreenath Narayan1, Jun Miao1, Fangping Huang1, David Johnson2, Guo-Qiang Zhang1, David Wilson1

1Case Western Reserve University, Cleveland, OH, United States; 2Ohio State University, Columbus, OH, United States

Compressed Sensing for 3 point Dixon method source image reconstruction has not yet been optimized for perceptual performance. In this abstract, we determine how to densely to sample each of the source images to achieve a given global sampling ratio.

3158. Comparison of Compressed Sensing and Keyhole Methods for Fat-Water Separation

Sreenath Narayan1, Jun Miao1, Fangping Huang1, David Johnson2, Guo-Qiang Zhang1, David Wilson1

1Case Western Reserve University, Cleveland, OH, United States; 2Ohio State University, Columbus, OH, United States

Dixon-type methods require multiple scans with different chemical shift weights. Keyhole methods have previously been used to reduce scan time. In this abstract, we compare keyhole methods and Compressed Sensing for quantitative studies.

Brain Image Analysis

Hall B Thursday 13:30-15:30

3159. Methodology for the Estimation of the Extension of a White Matter Tract Into and Through Associated Grey Matter

Daniel J. Tozer1, Declan Chard1, Olga Ciccarelli2, Benedetta Bodini2, David H. Miller1, Alan J. Thompson2, Claudia Angela Michela Wheeler-Kingshott1

1NMR Unit, Department of Neuroinflammation, UCL Institute of Neurology, London, United Kingdom; 2Brain Repair and Rehabilitation, UCL Institute of Neurology, London, United Kingdom

The definition of areas of grey matter (GM) that are associated with specific white matter tracts is important for studies investigating the spatio-temporal relationship between the two. The work proposes a method for extending a white matter tract calculated from diffusion MRI through the GM using a geometrical extension of those pixels on the tract edge, which are in or abut GM, to the nearest point on the outer GM boundary. It was found that running the extension in 3 orthogonal 2D planes included more tissue than running the process in 3D, which may be preferable in many cases.

3160. New Invariant Indexes to Quantify Water Anomalous Diffusion in Brain

Silvia De Santis1,2, Silvia Capuani1,2, Andrea Gabrielli3,4, Bruno Maraviglia, 1,5

1Physics department, Sapienza University, Rome, Italy; 2INFM-CNR SOFT, Sapienza University, Rome, Italy; 3SMC - CNR/INFM, Sapienza University, Rome, Italy; 4ISC - CNR, Rome, Italy; 5Neuroimaging Laboratory, S. Lucia Foundation, Rome, Italy

We propose a new procedure to detect the deviation from the mono-exponentiality of water diffusion in brain. The stretched-exponential model has been extended to three-dimensional space to obtain new scalar invariants. The potentiality of this methodology has been evaluated on young healthy subjects. Statistical analysis on selected ROIs from different cerebral tissues underlined a different contrast compared to conventional DTI one. In particular, GM and WM can be discriminated on the basis of their microstructural complexity, underlying a chance for investigating subtle changes of the water diffusive motion in tissues which are not detected by conventional MD and FA indexes.

3161. Spatial Normalization of Diffusion Spectrum Imaging Using Large Deformation Diffeomorphic Metric Mapping

Yung-Chin Hsu1, Ching-Han Hsu2, Wen-Yih Tseng3

1National Tsing Hua University, Hsin-Chu, Taiwan; 2National Tsing Hua University, Taiwan; 3Center for Optoelectronic Biomedicine and Department of Medical Imaging

Problems of image registration has been well studied in the neuroimaging field. However, the registration of the diffusion MRI data, especially to align the fiber orientations among different brains, is not readily applicable using current available packages. We generalized the conventional 3D registration to the 6D scenario by implementing LDDMM algorithm. The results demonstrate the proposed method is applicable for the registration between DSI datasets.

3162. Cortical Shape Analysis Using Spherical Wavelet Decomposition of Curvature

Kim Mouridsen1,2, Rudolph Pienaar3,4

1Neuroradiology, Center for Functionally Integrative Neuroscience, Aarhus, Denmark; 2Radiology, Massachusetts General Hospital, Boston, MA, United States; 3Radiology, Childrens Hospital Boston, Boston, MA, United States; 4Radiology, Harvard Medical School, Boston, MA, United States

We present a method to analyze cortical shapes based on wavelet decomposition of curvature functions. Using spherical harmonics as effective encoding, we show that groups of healthy controls and patients suffering from polymicrogyria may be identified using automated classification techniques.

3163. Is Quantitative T2 Sensitive to Tumor Cell Infiltration?

Tonima Sumya Ali1, Thorarin Bjarnason1, Beichen Sun1, Xueqing Lun1, Donna Senger1,2, Peter Forsyth1,3, Jeff Dunn1,4, Joseph Ross Mitchell1,3

1University of Calgary, Calgary, Alberta, Canada; 2Tom Baker Cancer Centre; 3Southern Alberta Cancer Research Institute; 4Hotchkiss Brain Institute

Quantitative analysis of multi-echo T2 relaxation has been used to examine micro compartmental structures in rat glioblastoma tumors. The infiltrative nature of malignant gliomas poses a major clinical challenge in rendering tumors incurable by conventional techniques. Recently, brain tumor initiating cells (BTIC) have been hypothesized to represent the cell of origin for these tumors. We analyzed 5 mouse brains in vivo inoculated with BTIC to characterize the changes in T2 distributions for each heterogeneous tumor. Based on the qualitative comparison between segmented geometric mean T2 map and histology staining, 4 regions were identified that corresponded to varying tumor cell densities.

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