Introduction/Purpose: Ultrasound, magnetic resonance imaging (MRI) and arthroscopy have been used in the diagnosis of shoulder injuries. This pilot study evaluated clinically affected dogs with shoulder lameness and 1) compared ultrasound to MRI findings 2) compared short and long MRI protocol findings to determine diagnostic value of a short MRI protocol for use as a sedated MRI examination in the future.
Methods: Dogs with shoulder lameness based on orthopedic exam were included. The long MRI protocol included intra-articular injection of gadolinium contrast and post- contrast sequences. The short protocol included four sequences, which were part of the long protocol. Directly following MRI, arthroscopy was performed. The MRI short and long protocols were randomized and graded by consensus by two radiologists. Ultrasound images were graded by a radiology resident. Each structure was scored for visibility, enlargement, signal change/echogenicity, and enthesopathy.
Results: Five dogs have been included. Scoring was similar between the long and short MRI protocols. Ultrasound identified soft tissue changes similarly to MRI. MRI identified cartilage thinning and subchondral bone changes in 4/5 dogs, compared to 1/5 dogs with ultrasound. Arthroscopy confirmed cartilage erosion in 3 dogs. The medial glenohumeral ligament (MGHL) was not confidently identified with ultrasound. MGHL abnormalities were noted on MRI in 3/5 cases and agreed with arthroscopy.
Discussion/Conclusion: Ultrasound under diagnosed the extent and degree of pathology to the MGHL. The short MRI protocol provided similar diagnostic information compared to the long MRI protocol and could potentially be used in sedated dogs with suspected shoulder pathology.