Magnetic resonance imaging and histological findings in the proximal aspect of the suspensory ligament of forelimbs in nonlame horses.

This research article explores the use and interpretation of Magnetic Resonance Imaging (MRI) and histological appearances of the suspensory ligament in the forelimbs of nonlame horses, providing detailed anatomical, MRI, and histological findings. The study considers various factors like age, breed, gender, height, and body weight in correlation to the MRI findings.

Study Objectives and Methodology

• The study had several objectives. Firstly, it aimed to detail the anatomy of the proximal suspensory ligament (PSL) in equine forelimbs. Secondly, the study sought to outline high- and low-field MRI and histological appearances of the PSL and related structures in horses without any forelimb pain, especially in the carpal or proximal metacarpal areas. The relationship between various factors (age, breed, gender, height, and body weight) and MRI findings was also assessed, and the histological appearance of the PSL was compared to MRI findings.
• For the methodology, the study analyzed high- and low-field MRI images of the PSL from 30 cadaver limbs of nonlame horses, subjectively and objectively. The association of age, breed, gender, height, and body weight with MRI findings was evaluated using univariable and multivariable linear regression analyses. Nine limbs were also subjectively compared for their histological and MRI findings.

Study Findings

• The collagenous tissue of the PSL in the MRI images showed varying low to intermediate signal intensity, depending on the pulse sequence. There was also a noticeably large variation among horses in the amount, shape, and signal intensity of muscle and adipose tissue within the PSL.
• When comparing MRI images to histological slides, areas of high signal intensity were seen to correspond to adipose tissue, while intermediate signal intensity areas matched muscle tissue.
• The medial lobe of the PSL was found to have a smaller cross-sectional area (CSA) than the lateral lobe.
• Lastly, statistical analysis revealed a significant positive correlation between the CSA of the PSL and both the horse’s height and body weight (P<0.001).

Conclusions

• The study concludes with the reflection that the significant variability found in the MRI appearance of the PSL in nonlame horses should be accounted for when interpreting MR images of lame horses. This refers to the differences in amounts, shapes, and signal intensities of muscle and adipose tissue within the PSL across the studied horses, as well as the noticeable variations in the collagens’ signal intensity.