Background FDG-PET can detect subclinical arthritis in the cervical vertebrae of patients with rheumatoid arthritis (RA).

Objectives In this study, we evaluated the grade of the synovitis in the atlantoaxial (AA) joint of RA patients using FDG-PET/CT, and measured its relationships with FDG uptake of other joints, the disease activity of RA, and laboratory findings.

Methods The institutional review board of the hospital approved the protocol for this study, and informed consent was obtained from each patient. Twenty three RA patients (6 men, 17 women, age 62.0±10.4 years old, disease duration 15.0±11.3 year) were included in this study. The FDG uptake into the AA joint, and the shoulders, elbows, wrists, hips, knees and ankle joints, were calculated using maximum standardized uptake value (SUVmax) for half-quantitative determination. The total of SUVmax of other joints except for AA joint was set to total SUV. The functional Xp of cervical spine was performed, and the existence and the grade of atlantoaxial subluxation (AAS) were checked. Clinical assessments, including the erythrocyte sedimentation rate (ESR), serum concentrations of CRP, and serum matrix metalloproteinase-3 (MMP-3), were performed. The activity of inflammation was evaluated using both the disease activity score (DAS) 28, simplified disease activity index (SDAI) and clinical disease activity index (CDAI).

Results The clinical data of all patients were as bellow, AA joint SUV; 2.26±1.04, total SUV; 26.3±9.9, DAS28; 5.11±1.23, SDAI; 23.1±15.4, and CDAI; 21.5±14.7. The AAS were detected in 3 RA patients, the ADI was 3 to 11 mm. AA joint SUV correlated with the age (r=0.554, p=0.006), total SUV (r=0.791, p<0.001), and AAS (r=0.448, p=0.032), respectively.

Conclusions This study suggested that FDG-PET could objectively evaluate the synovial inflammation of the atlantoaxial joints of RA patients.

Disclosure of Interest None Declared