Metabolic patterns of the shoulder joint on ¹⁸F- fluorodeoxyglucose positron emission tomography/computed tomography in adhesive capsulitis

Objective: The purpose of our study was to demonstrate metabolic patterns on ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) in patients with adhesive capsulitis (AC). Methods: We retrospectively reviewed ¹⁸F-FDG PET/CT performed on 22 shoulders of 21 patients diagnosed with AC: 2 shoulders with stage I, 14 with stage II, and 6 with stage III. A clinical diagnosis of AC was retrospectively made based on clinical examination, clinical course, and imaging. The pattern of radiotracer uptake was analyzed. Standardized uptake values in rotator interval (RI), anterior joint capsule (AJC), axillary recess (AR), and greater tuberosity were measured and compared to those of the contralateral side and the control group consisting of 40 shoulders in 20 subjects without shoulder pain. Results: Four patterns of uptake were noted: (1) glenoid type I (n = 16), with uptake in RI, AJC, and AR; (2) glenoid type II (n = 2),with uptake in AJC and AR; (3) glenoid type III (n = 2), with uptake in RI and AJC; (4) focal type (n = 2), with uptake in RI or AR. Affected side SUV_max for RI, AJC, and AR was significantly higher compared with the unaffected side and the control group. Two shoulders with stage I AC had patterns similar to the ones with stage II or III. Conclusion: Specific patterns of ¹⁸F-FDG uptake with dominant uptake in RI, AJC, or AR may be related to AC.