MR imaging detection of adhesive capsulitis of the shoulder: impact of intravenous contrast administration and reader's experience on diagnostic performance.

OBJECTIVE: Correct identification of adhesive capsulitis of the shoulder (ACS) has an important impact on adequate therapy. The aim of our study was to investigate the influence of intravenous contrast administration and of reader's experience on sensitivity and specificity of MRI in diagnosing ACS. MATERIALS AND METHODS: A total of 180 patients were included in a retrospective study: 60 subjects with at least 4 of 5 clinical signs of adhesive capsulitis of the shoulder and 120 patients with other shoulder diseases who underwent contrast-enhanced MRI. In a first session, only non-enhanced images and in a second session also contrast-enhanced (CE) series were independently evaluated by three radiologists with various levels of professional experience. Readers were blinded to all clinical information and had to rate the shoulder MRIs for absence or presence of adhesive capsulitis. Data analysis included McNemar's test, t test, and U test (p < .05). RESULTS: Using non-enhanced MRI, readers achieved a mean sensitivity of 63.9% and a mean specificity of 86.4%. By additional use of CE sequences, the mean sensitivity (85.5%) and the sensitivity for each reader increased significantly (p = .046, p < .01, p < .001, p = .045) while the improvement in mean specificity was not significant. Reader's experience had a positive effect on sensitivity and specificity, which was in part but not consistently significant. CONCLUSION: The addition of CE sequences can significantly increase the sensitivity of MRI in the diagnosis of ACS. Reader's experience has shown to be another important factor for the diagnostic outcome.