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ABSTRACTS from the 2018 ACVR IVRA Joint Scientific Conference

3D-Kinematics of the lumbosacral region in German shepherd dogs using biplanar cineradiography, computed tomography and scientific rotoscoping

Presenting Author: Nele Ondreka, DECVDI, European Specialist in Veterinary Diagnostic Imaging, Dr. med. vet. - Department of Small Animal Clinical Sciences, University of Giessen, Germany

Co-Author: Katharina I. Kopp, DVM - Department of Small Animal Clinical Sciences

Co-Author: Martin J. Schmidt, Prof., Dr. med. vet., DECVN - Department of Small Animal Clinical Sciences

Co-Author: Bernd Tellhelm, DECVDI, European Specialist in Veterinary Diagnostic Imaging, Dr. med. vet. - Department of Small Animal Clinical Sciences

Co-Author: Martin S. Fischer, Prof., Dr. rer. nat. - University of Jena

Morphology and motion of the lumbosacral junction are of strong interest in German Shepherd dogs (GSD) owing to their predisposition for cauda equina syndrome (CES). Synthesis of clinical and MRI findings is the standard diagnostic algorithm for CES. Limitations of static imaging are well known. Numerous attempts have been made to assess lumbosacral dynamics in terms of CES. However, detailed kinematics of the lumbosacral junction have never been displayed. We present the first detailed 3D analysis of pelvic and lumbosacral motion in 4 healthy GSD during natural locomotion. Scientific rotoscoping, a markerless XROMM method (x-ray reconstruction of moving morphology) workflow, and 3D bone marionettes were used. Hind limb, pelvic and lumbosacral motion varied between and within dogs. Hind limb and pelvic motion were linked representing transmission of hindlimb motion and force. No strong link was found between hind limb and lumbosacral motion. Overall, motion of the pelvis and the caudal lumbar spine was reciprocal to lumbosacral rotation. Intervertebral translation was minimal. Coupling of inverse pelvic and L7 sagittal rotation with cranial-caudal translation of L7 during trot was associated with increased translation of the lumbosacral disc space. The results underline that motion patterns are complex and can vary between individual dogs and even steps. The ROM of the lumbosacral junction is smaller than expected based on prior studies. The lumbosacral disc may experience increased stress at trot. This study provides the first insight into in vivo kinematics of the lumbosacral region and contributes to a better understanding of CES in GSD.

Characterization of positional variations in MRI appearance of equine distal interphalangeal joint cartilage: influence of the magic angle effect

Presenting Author: Britton K. Nixon, DVM - University of California Davis

Co-Author: Mathieu Spriet, DVM, MS, DACVR, DECVDI - University of California, Davis

MRI of the distal interphalangeal joint (DIPJ) is performed in the horse to evaluate for degenerative changes, but there has been little published data regarding equine cartilage. We hypothesize that magic angle effect contributes to regional variation in appearance of DIPJ cartilage via its influence on T2 relaxation times. MRI was performed of six cadaveric equine forelimbs using a 1.5 T MRI system with paired 3” surface coils. Sagittal FSPGR and T2 map sequences of the DIPJ were acquired in three standardized positions to vary the angle of the digit relative to B0. The cartilage of the DIPJ was divided into nine equal regions of interest (ROI) for the middle phalanx (P2) and six ROI for the distal phalanx (P3); signal intensity and T2 times were measured and compared among ROI. Cartilage signal intensity and T2 times varied between ROI and positions for P2 and varied between ROI for P3 (p ................
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