Low field magnetic resonance imaging of the equine distal interphalangeal joint: Comparison between weight-bearing and non-weight-bearing conditions.
Authors: Evrard Laurence, Audigié Fabrice, Bertoni Lélia, Jacquet Sandrine, Denoix Jean-Marie, Busoni Valeria
Journal: PloS one
Summary
# Editorial Summary Researchers used low-field MRI to investigate whether the distal interphalangeal (DIP) joint cartilage appears differently when horses bear weight compared to non-weight-bearing conditions—a clinically important distinction since standing MRI is increasingly used for lameness diagnosis. Ten forefeet were scanned whilst weight-bearing in a standing 0.27 Tesla system, then re-scanned post-mortem in the same anatomical position to control for positioning variables; cartilage thickness and joint space dimensions were measured at standardised landmarks on high-resolution three-dimensional T1-weighted images. Weight-bearing significantly reduced DIP cartilage thickness overall (p = 0.0001), with cartilage of the distal phalanx showing greater compression than the middle phalanx; nine blinded observers with varying experience correctly identified weight-bearing versus non-weight-bearing images in 83% of cases (range 65–95%), though success rates varied significantly between observers and experience groups. These findings suggest that cartilage degeneration and subtle pathological changes may be masked or harder to visualise on weight-bearing standing MRI due to normal compressive thinning, potentially leading to underdiagnosis of early DIP joint disease—an important caveat when interpreting standing examinations in horses with suspected navicular syndrome or other DIP joint pathology.
Read the full abstract on PubMed
Practical Takeaways
- •Standing weight-bearing MRI may underestimate or mask cartilage pathology due to normal physiological cartilage compression—consider non-weight-bearing positioning when evaluating distal interphalangeal joint cartilage lesions
- •Distal phalanx cartilage shows more dramatic thickness changes with weight-bearing than middle phalanx cartilage, so this region requires particular caution in image interpretation
- •Experienced radiologists can identify weight-bearing status from cartilage appearance alone in ~83% of cases, suggesting this is a consistent and measurable physiological effect
Key Findings
- •Weight-bearing distal interphalangeal cartilage was significantly thinner than non-weight-bearing cartilage (p = 0.0001), with greater changes in distal phalanx cartilage
- •Blinded readers correctly identified 83% of images as weight-bearing or non-weight-bearing based on cartilage appearance (range 65-95%)
- •Cartilage thickness reduction during weight-bearing may obscure identification of cartilage abnormalities on standing low-field MRI