MAGNETIC-RESONANCE-IMAGING OF THE WRIST IN EARLY RHEUMATOID-ARTHRITISREVEALS A HIGH PREVALENCE OF EROSIONS AT 4 MONTHS AFTER SYMPTOM ONSET

Objectives-To evaluate the role of magnetic resonance imaging (MRI) of the wrist in detecting early joint damage in patients with rheumatoid arthritis (RA). Methods-MRI was performed on 42 patients with early R A (median symptom duration of four months). Scans were scored separate ly by two musculoskeletal radiologists using a newly devised scoring s ystem, which was validated. MRI findings were compared with plain radi ography, clinical measures, and HLA-DRB01/04 genotyping. Results-Inte robserver reliability for the overall MRI score was high (r = 0.81) as was intraobserver reliability (r = 0.94 for observer 1 and 0.81 for o bserver 2). There was more variation in scoring synovitis (interobserv er reliability: r = 0.74). Erosions were detected in 45% of scans (19 of 42), compared with 15% of plain radiographs. The most common site f or erosions was the capitate (39%), for synovitis the ulnar aspect of the radiocarpal joint, and for tendonitis, the extensor carpi ulnaris tendon. The total MRI score and MRI synovitis score correlated most si gnificantly with C reactive protein (r = 0.40 and 0.42 respectively, p <0.01). The MRI erosion score was highly correlated with MRI bone marr ow oedema (r = 0.83) as well as the Ritchie score and disease activity score (r = 0.32, p < 0.05). HLA-DRB104 or *01 (shared epitope +ve) w as found in 76% of patients; 84% of those with MRI erosions and 69% of those without (NS, p = 0.3). Conclusions-A high proportion of RA pati ents develop MRI erosions very early in their disease, when plain radi ography is frequently normal. MRI of the dominant wrist may identify t hose requiring early aggressive treatment.