ROTATOR CUFF DISORDERS - INTEROBSERVER AND INTRAOBSERVER VARIATION INDIAGNOSIS WITH MR-IMAGING

PURPOSE: To determine interobserver and intraobserver variation in the interpretation of magnetic resonance (MR) images in rotator cuff diso rders. MATERIALS AND METHODS: MR images of the shoulder in 97 patients were retrospectively reviewed twice, with a 3-week interval. Surgical findings indicated a full-thickness tear in 29 patients, grade 1 impi ngement in 19 (tendinitis), and grade 2 impingement (partial tear) in 26. The control population comprised 23 asymptomatic volunteers or pat ients. RESULTS: All observers were accurate in the diagnosis of a full -thickness tear (89%-98%), with good intraobserver (kappa = 0.67-0.84) and interobserver agreement (kappa = 0.74-0.92). In diagnoses of tend initis, partial tear, and normal cuff, there were wide ranges of sensi tivity (13%-74%) and specificity (72%-93%), as well as poor interobser ver (kappa = 0.12-0.60) and intraobserver agreement (kappa = 0.35-0.78 ). CONCLUSION: Full-thickness tears of the rotator cuff can be accurat ely identified at MR imaging with little observer variation. Consisten t differentiation of normal rotator cuff, tendinitis, and partial thic kness tears is more difficult.