Findings consistent with equine proximal suspensory desmitis can be reliably detected using computed tomography and differ between affected horses and controls.
Authors: Eva M T Müller, K. Vanderperren, R. Merle, Svenja Rheinfeld, P. Leelamankong, C. Lischer, A. Ehrle
Journal: Veterinary radiology & ultrasound : the official journal of the American College of Veterinary Radiology and the International Veterinary Radiology Association
Summary
# Editorial Summary: CT for Diagnosing Equine Proximal Suspensory Desmitis Proximal suspensory ligament disease remains a challenging diagnosis in equine practice, particularly in regions without access to high-field MRI. This retrospective study compared CT imaging findings in 20 horses with clinically localised PSL pain against 20 control horses, with three independent radiologists grading both bone and soft tissue window images for specific abnormalities including osseous exostosis, sclerosis, mineralisation, and ligament enlargement. The diseased group demonstrated significantly elevated CT scores for exostosis (p = .015) and PSL enlargement (p = .004), with strong intraobserver reliability (ICC .82–1.0) and substantial to moderate interobserver agreement, particularly for mineralisation detection (kappa = .61). Measurements taken on soft tissue windows were consistently smaller than those on bone windows, suggesting that imaging protocol choice affects quantification of ligamentous changes. For practitioners managing suspected PSD without MRI availability, CT emerges as a reliable diagnostic tool capable of identifying characteristic osseous proliferation, sclerosis, and soft tissue pathology—though standardisation of measurement technique remains important for consistent interpretation across different imaging facilities.
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Practical Takeaways
- •CT is a reliable diagnostic tool for detecting proximal suspensory desmitis when high-field MRI is unavailable, with good reproducibility between observers
- •Look specifically for osseous exostosis and PSL enlargement as key indicators of PSD on CT — these show the clearest differences between affected and normal horses
- •Use soft tissue window settings for accurate PSL measurements; bone window images tend to overestimate soft tissue dimensions
Key Findings
- •CT identified significantly more abnormalities in horses with PSD compared to controls, with notably higher scores for osseous exostosis (p=0.015) and PSL enlargement (p=0.004)
- •Intraobserver agreement for CT findings was high (ICC 0.82-1.0), with substantial agreement for mineralization detection (kappa=0.61)
- •Soft tissue measurements were significantly smaller in bone window compared to soft tissue window imaging
- •CT can reliably detect PSD-related findings including osseous proliferation, sclerosis, soft tissue enlargement, mineralization, and avulsion