Comparison of cone beam CT and low‐field MRI of the distal limb of 85 horses
Authors: Taylor S. E., Kelly P., Daniel C., James O., McMaster M., Schwarz T.
Journal: Equine Veterinary Education
Summary
# Editorial Summary: Cone Beam CT and Low-Field MRI Comparison in Equine Distal Limb Imaging When evaluating distal limb pathology in standing sedated horses, veterinarians increasingly have access to both cone beam computed tomography (CBCT) and magnetic resonance imaging (MRI), yet clinical guidance on their relative strengths remains limited. Taylor and colleagues conducted a retrospective review of 85 horses that underwent both imaging modalities on the same day, examining 120 foot and 38 pastern regions to directly compare their diagnostic capabilities. MRI proved superior for identifying soft tissue injuries, detecting primary diagnoses in 24 horses where CBCT revealed no abnormalities, and demonstrating increased STIR signal intensity in 44 horses within the phalanges or navicular bone; conversely, CBCT excelled at evaluating cortical bone architecture, particularly the flexor cortex margins of the navicular bone and articular surfaces of the phalanges, with one case identifying a distal phalanx sequestration not initially apparent on MRI review. The practical implication for equine practitioners is that neither modality is redundant—MRI should drive diagnosis when soft tissue compromise is suspected, whilst CBCT provides superior assessment of cortical bone integrity and is particularly valuable in cases of solar penetration or when detailed evaluation of bone margins is clinically necessary. Using both modalities in tandem may optimise diagnostic yield in complex distal limb cases, though the authors note their findings derive from a mixed referral population and lack verification against a definitive gold standard.
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Practical Takeaways
- •If soft tissue injury is suspected in the distal limb, MRI should be the primary modality; CBCT alone may miss these lesions
- •Use CBCT when detailed cortical bone evaluation is needed, particularly for solar penetration cases or when assessing navicular bone margins and joint surfaces
- •Combined MRI and CBCT imaging provides the most complete diagnostic picture for complex distal limb cases, though cost and availability must be considered
Key Findings
- •MRI detected primary soft tissue injuries in 24 of 85 horses that were not identified on CBCT alone
- •44 horses showed increased STIR signal intensity on MRI within phalanges or navicular bone
- •CBCT provided superior visualization of cortical bone margins, particularly at the flexor cortex of the navicular bone and articular surfaces
- •Combined MRI and CBCT imaging yields complementary diagnostic information, with MRI superior for soft tissue and CBCT superior for cortical bone detail