Abstract

Background: Magnetic resonance imaging has been suggested in previous literature to be of high accuracy at academic institutions in identifying superior labral tears, however many Type II superior labrum anterior-to-posterior (SLAP) lesions encountered during arthroscopy are not previously diagnosed with non-contrast images. This study evaluated the accuracy of diagnosing Type II SLAP lesions in a community setting using non-contrast magnetic resonance imaging and analyzed the effect radiologist training and the scanner type or magnet strength had on sensitivity and specificity. Methods: One hundred forty-four patients requiring repair of an arthroscopically confirmed Type II SLAP lesion that had a non-contrast magnetic resonance examination performed within twelve months of the procedure were analyzed for sensitivity. An additional one hundred patients with arthroscopically confirmed normal superior labra were identified for specificity. The radiologists’ transcribed interpretations of the images were used to document the diagnosis of a SLAP lesion and compared to the surgical operative report. The magnet strength, type of system (open or closed) and whether the radiologist had completed a musculoskeletal fellowship were also recorded. Results: Non-contrast magnetic resonance imaging identified SLAP lesions in fifty-four out of one hundred forty-four cases, yielding an overall sensitivity of 38% (95% CI = 30%, 46%). Specificity was determined to be 94% (95% CI = 87%, 98%), with six SLAP lesions diagnosed out of one hundred shoulders that did not contain the lesion. Musculoskeletal fellowship trained radiologists performed with higher sensitivity than those that had not completed the fellowship (46% vs. 19%, p = 0.009). Conclusions: Our results demonstrate a low sensitivity and high specificity in diagnosing Type II SLAP lesions with non-contrast magnetic resonance imaging in this community setting. Musculoskeletal radiologists had significantly higher sensitivities than non-musculoskeletal radiologists. This study indicates that non-contrast magnetic resonance imaging is not a reliable diagnostic tool for Type II SLAP lesions in a community setting.