Fat-suppressed spoiled gradient-recalled imaging of equine metacarpophalangeal articular cartilage.

This research aimed to determine the effectiveness of 1.5 T magnetic resonance (MR) imaging in examining articular cartilage in racehorses’ metacarpophalangeal joints affected by osteoarthritis. The results suggest that MR imaging provides a reasonably precise method to evaluate structural changes in the joint cartilage.

Research Methodology

• The researchers used a sagittal, three-dimensional spoiled gradient-recalled echo (SPGR) with fat saturation (FS) sequence, a specific type of imaging, to study 20 ex vivo joints.
• They dissected each joint and designated specific areas on the third metacarpal condyle for further evaluation. These areas were then sampled for cartilage thickness measurement and assessed by a modified Mankin scale, a common method used to quantify degenerative changes in cartilage.
• Cartilage thickness and signal intensity were also measured on MR images at the selected metacarpal sites.
• The structure of the cartilage was then graded (on a scale of 0-3) at the macroscopic level and on MR images by two examiners. This grading took place in defined subregions of the proximal phalanx, third metacarpal, and proximal sesamoid bones.

Key Findings

• There was a good precision level and moderate correlation between the cartilage thickness measurements taken from the MR images and histology. The slightly larger average thickness reported in the MR images could be due to factors such as hardware, software, or measurement variability.
• The study shows a moderate correlation between the modified Mankin histologic score (which grades the general histological structure of the cartilage) and the signal intensity of the cartilage or MR cartilage structure assessment on SPGR-FS.
• Sensitivity of the MR imaging for detecting full-thickness cartilage erosion was moderate and such lesions were often underestimated, particularly if they were linear. However, the specificity or the ability to correctly identify those without lesions was high.

Conclusion

• Despite certain limitations, the application of an SPGR-FS sequence in MR imaging is a reasonably accurate method for assessing structural changes affecting the articular cartilage in the equine metacarpophalangeal joint.
• However, it is important to consider further investigation to determine the best practice for detecting cartilage erosions accurately.