MR imaging of atlantoaxial joint in early rheumatoid arthritis

This study was done to assess the involvement of the atlantoaxial joint in patients with early rheumatoid arthritis and evaluate the role of magnetic resonance (MR) imaging in depicting this early joint involvement.

Twenty patients (16 women and four men, mean age 55.0±12.9 years) with clinical and laboratory evidence of early rheumatoid arthritis (mean disease duration <12 months) were included in our study. MR imaging of the atlantoaxial joint was performed in all patients within 3 months from diagnosis. The MR features were correlated with clinical and biochemical variables.

Five (25.0%) of the 20 patients exhibited enhancement of the periodontoid synovial spaces after gadolinium administration due to inflammatory synovitis. Compared with patients without cervical involvement, these five patients showed significantly higher values of erythrocyte sedimentation rate [median 77.0 mm/h (range 25th and 75th percentile 69.0-86.0) vs median 33.0 mm/h (range 25th and 75th percentile: 9.2-52) (p=0.007)]; significantly higher C-reactive protein values [median 53.6 mg/l (range 25th and 75th percentile 21.9-81.9) vs median 14.0 mg/l (range 25th and 75th percentile 0.8-20) (p=0.03)]; higher disease activity score [median 4.2 (range 25th and 75th percentile 3.9-5.4) vs median 3.2 (range 25th and 75th percentile 2.8-3.8) (p=0.03)]. Four (80%) of these five patients presented anti-citrulline antibodies (anti-CCP) and rheumatoid factor at laboratory testing. The latter was positive in 12 of the 20 patients (66%), and anti-CCP were positive in 15 (83%).

MR imaging showed an atlantoaxial inflammatory synovitis in 25% of patients with early rheumatoid arthritis. Our results indicate that patients with higher disease activity are likely to be at higher risk of presenting early involvement of the atlantoaxial joint. MR imaging of the cervical spine is an excellent tool for assessing the early manifestations of rheumatoid arthritis before any destructive changes occur. Therefore, MR imaging should be included in the diagnostic workup in order to provide reliable guidance for treatment choices.