Reliability of high- and low-field magnetic resonance imaging systems for detection of cartilage and bone lesions in the equine cadaver fetlock.
Authors: Smith M A, Dyson S J, Murray R C
Journal: Equine veterinary journal
Summary
# Editorial Summary: MRI Reliability for Equine Fetlock Lesion Detection Smith, Dyson and Murray compared high-field and low-field MRI systems against histopathological findings in 19 cadaver fetlocks to establish their reliability for detecting cartilage and bone pathology—a critical question given MRI's widespread use in lameness diagnosis. Using standardised grading systems and sensitivity/specificity analysis, the researchers found that whilst both imaging systems showed high sensitivity for cartilage lesions, specificity was disappointingly low, meaning clinicians must expect a substantial proportion of false-positive diagnoses when interpreting these findings. Conversely, trabecular bone lesions were detected with moderate-to-good reliability on both systems, particularly on low-field T2*-weighted gradient echo sequences, whereas subchondral bone showed the problematic combination of high sensitivity but low-to-moderate specificity. The practical takeaway is sobering: independent review of multiple pulse sequences may improve diagnostic accuracy, but clinicians should exercise caution when basing treatment decisions solely on MRI evidence of cartilage or subchondral pathology without corroborating clinical signs, lameness localisation, or ultrasound findings, since the high false-positive rate could lead to unnecessary interventions or incorrect case management.
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Practical Takeaways
- •MRI reports of cartilage and subchondral bone lesions in the fetlock should be interpreted cautiously, as false positives are common; histopathology or additional diagnostic confirmation may be warranted before committing to treatment.
- •When MRI shows trabecular bone involvement, the findings are more likely to be reliable than cartilage findings, making trabecular pathology a more useful diagnostic indicator.
- •Review multiple pulse sequences independently rather than combining them, as this approach may better capture true lesions in the fetlock.
Key Findings
- •High-field T2*W-GRE and low-field T2W-FSE images showed high sensitivity but low specificity for cartilage lesion detection, with high likelihood of false positives compared to histopathology.
- •MRI had moderate-high likelihood of false positive results for subchondral bone lesions across both field strengths and pulse sequences.
- •Trabecular bone lesions were more reliably detected on MRI than cartilage or subchondral bone, with low-field T2*W-GRE showing higher sensitivity and specificity than T2W-FSE.
- •Combining interpretation results from different pulse sequences did not improve detection rates for cartilage lesions.