MR imaging signs of shoulder adhesive capsulitis: analysis of potential differentials and improved diagnostic criteria.

Objective: To evaluate the prevalence of shoulder adhesive capsulitis (AC) signs on MR studies of patients with various common shoulder conditions.

Methods: MR images of 316 patients were retrospectively evaluated. Patients were divided into three groups: controls (66 patients), clinical AC (63 patients), and study group (187 patients). The final diagnosis of AC was reached clinically. The study group was composed of patients with focal and massive rotator cuff tears, active hydroxyapatite deposition disease, fractures around the shoulder, and post-surgery. The following AC signs were evaluated: inferior glenohumeral ligament (IGHL) thickening; coracohumeral ligament (CHL) thickening; and hyperintensity of the inferior glenohumeral ligament, which was graded in four classes.

Results: The IGHL signal intensity was statistically higher in patients with fractures than in controls (P = 0.008). There was no statistically significant difference in IGHL signal between the AC group and patients with massive rotator cuff tears and active hydroxyapatite deposition disease (P > 0.1). IGHL thickness in patients with fractures, massive rotator ruptures, and active hydroxyapatite deposition disease was significantly higher compared to controls (P < 0.02) and significantly lower compared to the AC group (P < 0.0001). Based on these findings, a grading system for fibro-inflammatory capsular changes is proposed.

Conclusion: MR AC signs are frequent in patients with shoulder conditions other than AC; however, in these patients, capsular changes are less prominent than in patients with clinical AC.