Abstract
ObjectiveBecause positron emission tomography/computed tomography (PET/CT) using fluorine-18-fluorodeoxyglucose (18F-FDG) can be used to visualize inflammation of the musculoskeletal system, it may help elucidate the pathophysiology of frozen shoulder (FS). The purpose of this study was to characterize the uptake pattern on 18F-FDG PET/CT in patients with idiopathic FS and to determine if there is a correlation between its metabolic parameters and clinical findings.Methods18F-FDG PET/CT was conducted to 35 patients with unilateral idiopathic FS. Clinical data including pain, functional scores, and passive range of motion (ROM) were collected. Maximum standardized uptake values (SUVmax) were measured at the four regions of interest (ROIs): rotator interval (RI), anterior joint capsule (AJC), axillary recess (AR), and posterior joint capsule (PJC) from the attenuation-corrected axial images.ResultsMean SUVmax values for four ROIs of the affected shoulder were significantly higher than those of the unaffected shoulder. Mean SUVmax values of RI and AR were significantly higher than those of AJC and PJC and mean SUVmax of AJC was significantly higher than that of PJC in the affected side. Three recognizable patterns of increased uptake were noted: (1) AR dominant type (15 patients); (2) RI dominant type (9 patients); (3) both RI and AR dominant type (11 patients). The SUVmax of AR showed negative correlation with abduction and forward flexion. The SUVmax of RI showed negative correlation with external rotation and internal rotation. The SUVmax of AJC showed negative correlation with all ROMs. However, there was no significant correlation between the SUVmax of PJC and any ROM.ConclusionOur study demonstrates that the anterior–inferior capsular portion, including RI and AR, is the main pathologic site of idiopathic FS and reveals significant correlations between ROM and metabolic parameters on 18F-FDG PET/CT. These results imply that AR and RI lesions are related to elevational limitations and rotational limitations, respectively.
Highlights
Frozen shoulder (FS) is one of the most common shoulder disorders which is characterized by shoulder pain and limited range of motion (ROM) [1]
There was no significant correlation between the SUVmax of posterior joint capsule (PJC) and any ROM
Our study demonstrates that the anterior– inferior capsular portion, including rotator interval (RI) and axillary recess (AR), is the main pathologic site of idiopathic FS and reveals significant correlations between ROM and metabolic parameters on 18FFDG positron emission tomography/computed tomography (PET/CT)
Summary
Frozen shoulder (FS) is one of the most common shoulder disorders which is characterized by shoulder pain and limited range of motion (ROM) [1]. Arthroscopy and imaging studies have demonstrated loss of axillary recess (AR) fold, capsular contracture, rotator interval (RI) thickening and fibrosis including contracture of the coracohumeral ligament, and adhesion of the subacromial bursa in FS [3,4,5,6,7]. Recent studies demonstrated that specific patterns in positron emission tomography (PET) using fluorine-18-fluorodeoxyglucose (18F-FDG) are related to shoulder diseases including osteoarthritis and FS [9,10,11,12]. There are few reports that explain the relationship between the pathologic sites and patterns of ROM limitation. The purpose of this study was to determine whether there are specific patterns or outstanding sites of 18F-FDG uptake of the shoulder joint on 18F-FDG PET/CT for idiopathic FS and to elucidate which areas of uptake are related to the patterns of ROM limitation. We hypothesized that 18F-FDG uptake would be focused in the AR and RI, and uptake in AR would be related to elevational limitations and uptake in RI would be related to rotational limitations
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