Background Rheumatic diseases including rheumatoid arthritis (RA) have been investigated using 18FDG-PET (PET). A relationship has been identified among the disease activity, the progress of the joint destruction and the PET findings. In addition, there have so far been few reports about the relationship between PET and synovitis in magnetic resonance imaging (MRI) of the wrist and knee. However, the relationship between synovitis in MRI and the uptake in PET of the shoulder joints is unclear, as is the cut-off line of the standardized uptake value (SUV).
Objectives The aim of this study is to assess the PET findings and synovitis of the shoulder joints in the MRI findings in RA patients.
Methods Forty-three shoulders in 42 patients with RA were assessed with PET and MRI. The mean age (range) was 54 years (36–75) and the mean disease duration was 9 years (1–40).
18F-FDG uptake was quantified using the maximum pixel value of the SUV. Synovitis in shoulder MRIs was examined in the axillary pouch (AP), subacromial bursa (SAB), subdeltoid bursa (SDB), rotator interval (RI) and acromioclavicular joint (ACJ). The relationships between synovitis and SUV were examined.
Results The mean PET SUVmax (range) was 1.99 (0.87-6.17). MRI showed that 8 of 43 shoulders had synovitis in the AP, 17 in the SAB, 12 in the SDB, 16 in the RI and 5 in the ACJ. The total number of synovitis sites was significantly correlated with the SUV (R=0.72, P<0.01). The area under an ROC curve was 0.88. The sensitivity was 0.833 and specificity was 0.842 with a SUV cut-off line of 1.50.
Conclusions The SUV of the PET reflected synovitis of the shoulder MRI in patients with RA. The cut-off level of the SUV was 1.50 in an RA shoulder joint.
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Disclosure of Interest None Declared