PET (SUV) Quantitative Imaging
[Pages:12]PET (SUV) Quantitative Imaging
10/25/2011 R. Doot
Robert K. Doot, PhD Senior Research Scientist Department of Radiology University of Washington
PET Quantitative Approaches: Outline
? Why quantify FDG PET uptake? ? Biochemistry and kinetics of FDG ? Approaches to quantitative analysis ? Factors that affect quantitative accuracy ? Quantitative imaging - what is required?
10/25/2011 R. Doot
Why Quantify PET Images?
Patient 1
Before Therapy
After Therapy
10/25/2011 R. Doot
Patient 2
FDG PET uptake predicts outcome of bone-dominant breast cancer
Time to progression
Time to skeletal-related event
10/25/2011 R. Doot
(Specht Br Ca Res Treat 2007)
Page
Why Quantify FDG Uptake?
? Helps identify malignancy ? Provides other information:
? Prognosis ? "Grade" ? Correlation with tumor biology ? Key for assessing response ? Why not? - no extra work
10/25/2011 R. Doot
Requirements for Quantitative Analysis of FDG PET Scans
? Attenuation-corrected scans ? Cross-calibration between PET
tomograph and dose calibrator ? ROI analysis software ? Standard imaging time after injection ? Measurement of plasma glucose
10/25/2011 R. Doot
FDG PET Quantitative Analysis
FDG Biochemistry, and Kinetics
10/25/2011 R. Doot
FDG: Tracer of Glucose Metabolism
Glucose
18F-fluorodeoxyglucose
(FDG)
Blood Cell
Glucose
Glucose-6P
FDG
FDG-6P
Glycolysis
Increased glycolysis commonly observed in cancer (Warburg 1930)
10/25/2011 R. Doot
Page
Model of FDG Uptake
Blood Tissue
Blood FDG
Tissue FDG
PET Image
Trapped FDG-6P
10/25/2011 R. Doot
FDG Kinetics : Effect of Blood Clearance
High metabolism Medium metabolism
SUV
Metabolically Inactive Blood
FDG Injection
Time
Time is required for clearance from tissues without trapping
10/25/2011 R. Doot
(after Hamburg, JNM 35:1308, 1994)
Approaches to Quantifying FDG Uptake
10/25/2011 R. Doot
FDG PET Imaging Methods
Acquisition
Qualitative
Whole-body imaging
Analysis
Visual Inspection
Quantitative
Static Dynamic
10/25/2011 R. Doot
Standard Uptake Value (SUV) Glucose Metabolic Rate
Page
Glucose Metabolic Rate Estimation
Dynamic Imaging
Time
Region-of-Interest Analysis Time-Activity Curves
Kinetic Modeling
Glucose (FDG) Metabolic Rate
10/25/2011 R. Doot
Activity (?Ci/ml)
Time
Tissue Blood
FDG Tracer Kinetic Model: to Calculate Metabolic Rate (MRFDG)
Blood Tissue
Blood FDG
K1 k2
Tissue FDG
k3 k4
PET Image
Trapped FDG-6P
Glucose
10/25/2011 R. Doot
Flux Constant, Ki
MRFDG = [Glucose] Ki
Ki = K1k3/(k2+k3)
Activity Normalized
Activity Activity
Graphical (Patlak) Analysis
Flux
Blood Tracer
(Cb)
Tissue Tracer
T
Bound Tracer
B
Ct/Cb = Ki Cbd /Cb + (V0 +Vb)
ref: Patlak et al JCBFM 3:1, 1983
Blood
Slope = Ki
Tissue
10/25/2011 R. Doot
Simple Uptake Ratios: Standard Uptake Value (SUV)
SUV =
Average Tissue Uptake
Time
Tissue Tracer Activity (mCi/g)
(Injected Dose (mCi)/Pt weight (kg))
10/25/2011 R. Doot
Estimate of Tracer Availability
Page
SUV: An Illustration
Inject 7 mCi
(ID)
Into a 70 kg
water bucket (W)
Activity = 0.1 ? Ci/mL
Activity 0.1
SUV
=
= 1 g/mL
= ID/W
7/70
10/25/2011 R. Doot
Standard Uptake Value (SUV)
Tissue Tracer Activity (?Ci/g) SUV =
(Injected Dose (mCi)/Pt weight (kg))
Tissue Typical FDG SUV
Lung Bone Marrow Breast Liver Tumor
0.7 1.0 0.5 2.5 > 3-4
Zasadny, Radiology 189: 847,1993
10/25/2011 R. Doot
Why measure in SUV (an example)?
? PET scanner measures the radioactivity per unit volume ? Typically measured as kBq/ml or ?Ci/ml ? Interested in local areas with high or low uptake
70 kg water = 70 L
inject
10 mCi = 370 MBq
Net concentration = 370,000 kBq / 70,000 ml
= 5.3 kBq/ml
A very small object that takes up 5x net concentration, so its local concentration = 26.5 kBq/ml
10/25/2011 R. Doot
Impacts of injected dose & distrib. volumes
Injecting different amounts or changing volume will change concentration while relative uptake compared to background is constant
70 kg = 70 L
10 mCi = 370 MBq
concentration = 5.3 kBq/ml
26.5 kBq/ml
5 mCi = 185 MBq
10 mCi = 370 MBq
10/25/2011 R. Doot
concentration = 2.64 kBq/ml
13.2 kBq/ml
concentration = 10.6 kBq/ml
35 kg = 35 L
53.0 kBq/ml
Page
Standardized uptake values (SUVs)
Normalize by amounts injected per volume (i.e. weight) to get the same relative distribution with SUV = 1.0 for a uniform distribution
70 kg = 70 L
Overall SUV = 5.3 kBq/ml / (370MBq/70 Kg) = 1.0 g/ml
10 mCi = 370 MBq
5 mCi = 185 MBq 10 mCi = 370 MBq 10/25/2011 R. Doot
SUV = 5.0
SUV = 1.0 g/ml
SUV = 5.0
SUV = 1.0 g/ml
35 kg = 35 L
SUV = 5.0
Hot spot has same SUV values independent of activity injected or volume of distribution (i.e. patient size)
Measuring uptake: kBq/ml versus SUV
Same scale for kBq/ml
Same scale for SUV
10/25/2011 R. Doot
Slide Courtesy of Paul Kinahan
Liver values look more uniform between patients
SUV versus MRFDG to Measure
Response in Serial FDG PET Scans
% Change SUV vs % Change MRFDG in 39 Breast Cancer Pts with Neo-Adjuvant Therapy
0
r = 0.84
-20
but .....
Slope = 0.75
-40
(i.e., % change not equal)
SUV % Change
-60
-80
Slope: 0.75 ? 0.08
-100 -100 -80 -60 -40 -20 0
MRFDG % Change
(Doot J. Nucl. Med. 48:920, 2007)
10/25/2011 R. Doot
Intercept not at -100%
(SUV dose not go to 0)
Conclusion: SUV may underestimate response for low SUV tumors (< 3 pre-Rx)
Simpler Approaches to FDG Quantitative Analysis
Blood Tissue
PET Image
Blood FDG
Tissue FDG
Trapped FDG-6P
Uptake Ratio = Tracer in Tissue Tracer Available in Blood
10/25/2011 R. Doot
Page
SUV Loses Sensitivity at Low Values
Ability to measure response depends on pre-therapy SUV
All Patients
Pre-Rx SUV < 3 Pre-Rx SUV > 3
Dynamic range for response reduced by 35% for low pre-Rx SUV
10(/D25o/2o01t1JR..NDouoct l. Med. 48:920, 2007)
FDG SUV
Factors Affecting Quantitative Precision and Accuracy
10/25/2011 R. Doot
SUV Error sources
5 sources of measure error: ? PET image acquisition and analysis ? Patient prep ? Dose calibrator ? Weight scale for patient ? Clocks synchronization
Tissue tracer activity concentration (?Ci/g)
SUV =
(Injected dose (mCi)) / Pt. weight (kg))
10/25/2011 R. Doot
PET Data Acquisition and Image Reconstruction
Acquire Projection Data
Organize Data Into Projections
(Sinograms)
Image of Tracer Concentration
Image Reconstruction
Coincidence Detection
10/25/2011 R. Doot
Scatter Correction Randoms Correction Attenuation Correction
Calibration to a Standard
Page
Scanner Calibration
Scan Phantom with Uniform Activity
Measure Aliquot of Activity in Dose Calibrator
or Well Counter
PET scanner calibrated quarterly and responsibility of hospital
10/25/2011 R. Doot
Physical effects in PET
? Spatial resolution limitations ? Positron range ? Angular deviation of annihilation photons ? Instrumentation limitations ? Depth-of-interaction in detector
? Count rate limitations ? Dead time ? Random Coincidences ? Scattered coincidences
? Photon attenuation
10/25/2011 R. Doot
Effects of Attenuation: Patient Study
reduced mediastinal
uptake
'hot' lungs
Nonuniform
liver
Enhanced skin uptake
PET without attenuation correction (no direct physical
meaning to values)
PET with attenuation correction (accurate)
CT image (accurate)
Summary: All quantitative corrections have to be applied. Attenuation correction is most important and the biggest potential source of error if things go wrong
10/25/2011 R. Doot
Slide Courtesy of Paul Kinahan
Effect of Attenuation on Image Quality
Thin
not Thin
Scans performed using the same scanner and protocols
10/25/2011 R. Doot
Slide Courtesy of Paul Kinahan
Page
................
................
In order to avoid copyright disputes, this page is only a partial summary.
To fulfill the demand for quickly locating and searching documents.
It is intelligent file search solution for home and business.
Related download
- pet suv quantitative imaging
- perceptions of sport utility vehicle suv safety by suv
- consumer reports names the most reliable used cars
- c 2836 arnott coil spring conversion kit for
- iihs updates used vehicle list for teens shows why small
- the diagnostic utility of the lognormal behavior of pet
- best used trucks under 10000 consumer reports
- 10 safety tips for suv drivers a d dern
- the arms race on american roads the effect of
- best second hand suv 2012 uk
Related searches
- advent health imaging lake underhill
- hill s pet nutrition president hill s pet nutrition
- imaging cpt codes list
- mri imaging parameters
- mri imaging center
- abnormal imaging lung icd 10
- icd 10 abnormal imaging chest
- abnormal imaging chest icd 10 code
- abnormal imaging icd 10
- abnormal imaging icd 10 code
- intrathoracic organ imaging abnormality icd 10
- adventist healthcare imaging rockville md