Validity of noncontrast magnetic resonance imaging in diagnosing superior labrum anterior-posterior tears

Background: The biceps labral complex has received much interest in recent years as a source of shoulder pain. Magnetic resonance imaging (MRI) is the imaging modality of choice for those patients with a suspected superior labrum anterior-posterior (SLAP) tear. The goal of this study was to look at the accuracy of MRI without arthrography to correctly identify SLAP tears. Methods: The study had a prospective, case-based, case-control design. Participants were consecutive patients seen at an orthopaedic outpatient clinic who received an MRI scan as part of their diagnostic cycle. All patients were aged at least 18 years, with various shoulder dysfunctions (impingement, rotator cuff tear, and so on) that were evaluated during a routine clinical evaluation. Arthroscopic surgery was performed as the reference standard for a SLAP lesion. Results: Seventy-seven patients were evaluated during arthroscopic surgery. The pretest probability of a SLAP lesion-only diagnosis was 18.2%, and for a SLAP lesion with or without a concomitant diagnosis, the pretest probability was 66.2%. In both cases, use of MRI led to post-test probability values that were worse when a positive finding was identified on the MRI scan. Discussion: The results of this study suggest that SLAP tears are often incorrectly diagnosed based on MRI evaluation, with MRI providing a high level of sensitivity and low level of specificity. On the basis of the results of this study, conventional MRI is not a suitable test to accurately evaluate the biceps labral complex for the presence of a SLAP tear.