Magnetic Resonance Findings in the Carpus and Proximal Metacarpal Region of Non-Lame Horses

1. Introduction
Magnetic resonance imaging (MRI) is becoming more frequently used in the investigation of proximal metacarpal and carpal region pain. Magnetic resonance (MR) examination of the carpus and proximal metacarpal region is possible in some low-field and high-field magnets. One low-field system^a  has the advantage of performing MR examination in a standing sedated horse and can provide useful diagnostic information; however, the images are of inferior quality compared with high-field images or images obtained with the horse under general anesthesia because of both lower resolution and problems of motion artefacts. An in-depth knowledge of anatomy, the normal appearance of tissues, and their variations in high-field images is essential for accurate interpretation of low-field images. The few published studies on MR anatomy of the carpus and proximal metacarpal region^1–5 were based on high-field images and did not describe variants in non-lame horses. In a cadaver study, we recently described and compared high-field and low-field MR appearance of the carpus and proximal metacarpal region of 30 horses with no history of carpal or proximal metacarpal pain. The aim of this paper is to highlight those MR findings and variants in the carpus and proximal metacarpal region of non-lame horses using high-field and low-field MR images. This should aid understanding and interpretation of MR and conventional diagnostic imaging findings in lame horses. [...]