Standing MRI for surgical planning of equine fracture repair.

OBJECTIVE: To report the feasibility of standing MRI (sMRI) and document the value of sMRI in surgical planning for surgical repair of limb fractures in the horse. STUDY DESIGN: Retrospective case series. ANIMALS: Thirty-one horses with preoperative sMRI. METHODS: Medical records were reviewed for fracture type, application of a polyester cast, sMRI sequences performed, technical variables, and image quality. Fracture geometry and concomitant lesions were compared between sMRI and radiography. The relative value of sMRI with regard to surgical planning was classified as minor (sMRI did not provide additional findings), intermediate (additional lesions found or slight modification to surgical plan), or major (sMRI led to significant alternations in surgical plan). RESULTS: Standing MRI provided good studies in all horses. Standing MRI was classified as having major relevance in 12 of 31 horses, intermediate relevance in 14 of 31 horses, and minor relevance in 5 of 31 horses. CONCLUSION: Preoperative sMRI produced good studies in all horses and influenced the surgical planning in the majority of fractures in this study. Application of a polyester cast seemed to improve comfort without appreciable loss of image quality. CLINICAL SIGNIFICANCE: Standing MRI can be considered as an adjunct to plan the repair of equine fractures, and a polyester cast does not impair image quality.

Metacarpophalangeal joint injury patterns on magnetic resonance imaging: A comparison in racing Standardbreds and Thoroughbreds.

The metacarpal condyle has received extensive attention as a predominant site of overload arthropathy in racehorses. However, detailed descriptions of MRI lesion patterns for the metacarpophalangeal joint and comparisons between types of racing horses are currently lacking. Aims of this retrospective, cross-sectional study were to describe and compare standing low-field magnetic resonance findings in the metacarpophalangeal joints for groups of Standardbreds and Thoroughbreds using systematic semiquantitative scores. Data archives at the Clinique Vétérinaire Equine de Chantilly and Imavet were searched during the period from June 2010 to February 2016. Images were retrieved and reviewed by one reader. A total of 30 Standardbreds and 77 Thoroughbreds were sampled. The Thoroughbreds developed a much higher rate of stress fractures (40.3% vs. 10%) and overall more severe scores of subchondral sclerosis and bone marrow lesions than Standardbreds. The Standardbreds had more sites of subchondral bone defect and resorption, as well as higher synovitis and joint capsule thickening scores. Both Standardbreds and Thoroughbreds frequently developed multifocal subchondral lesions not limited to the distal palmar condyle. The Standardbreds had a higher tendency to develop dorsomedial joint pole subchondral injuries. Both Standardbreds and Thoroughbreds developed a noticeably high rate of periarticular soft tissue injuries (36.7% in Standardbreds and 20.8% in Thoroughbreds), which were rarely considered as the main contributors to the lameness. Findings supported the use of low-field MRI as a whole-organ assessment tool for Standardbreds and Thoroughbreds with suspected metacarpophalangeal joint injuries.

Comparison of inversion recovery gradient echo with inversion recovery fast spin echo techniques for magnetic resonance imaging detection of navicular bone marrow lesions in horses.

OBJECTIVE: To compare navicular bone marrow lesion (BML) conspicuity in the feet of horses as determined via 2 fat-suppressed MRI techniques, including standard short tau inversion recovery (STIR) and inversion recovery gradient echo (IRGE). SAMPLE: Feet (n = 150) of horses with lameness referable to the distal portion of the digit. PROCEDURES: STIR and IRGE sequences were obtained prospectively in all feet with a standing low-field equine MRI system. Presence of a BML was ascertained by identification of a characteristic combination of marrow alterations in T1-weighted, T2*-weighted, T2-weighted, and STIR images. Signal-to-noise and contrast-to-noise ratios were calculated on STIR and IRGE sequences in 56 feet with a navicular BML. RESULTS: Signal-to-noise and contrast-to-noise ratios of both sequences correlated linearly (r = 0.87 and r = 0.92, respectively) but were significantly higher for STIR images (mean ± SD, 22.6 ± 12.7 and 12.4 ± 11.4, respectively), compared with IRGE images (13.7 ± 8.0 and 5.9 ± 7.2, respectively). CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that the IRGE sequence revealed BMLs significantly less conspicuously, compared with the standard STIR sequence. The 2 techniques cannot be used interchangeably, and IRGE is therefore not recommended as the sole fat-suppressed sequence for routine equine standing MRI protocols.