Qualitative Comparison of 0.27T, 1.5T, and 3T Magnetic Resonance Images of the Normal Equine Foot

Magnetic resonance (MR) imaging has become an important diagnostic tool in the investigation of foot pain in horses. The aim of this study was to qualitatively compare ex-vivo MR images of the same equine feet obtained at three magnetic field strengths: 0.27, 1.5, and 3 tesla (T). Ten cadaver feet were used. All feet were imaged with two high-field systems (3T, 1.5T) and with a low-field (LF) system at 0.27 T designed for standing horses. Images were acquired using similar pulse sequences in all 3 MR units. MR images were subjectively evaluated by three independent experienced image analysts for image quality and clarity of visualization of individual anatomical structures using a four-point grading scale. The images from all of the examinations were considered to be of diagnostic value except for the hoof capsule where substantial artifacts were present in LF images with distortion and loss of signal at the dorsal/distal aspect of the hoof capsule in LF images. Anatomical structure scoring values of images obtained at 3T and 1.5T were significantly greater than scores of images obtained at 0.27T. Scores for images obtained at 3T were significantly higher than those for images obtained at 1.5T. Mean score differences between 1.5T and 3T were higher for cartilage of the distal interphalangeal joint and for the ungular cartilages.