Early-stage rheumatoid arthritis: prospective study of the effectiveness of MR imaging for diagnosis.

PURPOSE To assess the effectiveness of magnetic resonance (MR) imaging for the diagnosis of early-stage rheumatoid arthritis (RA). MATERIALS AND METHODS Fifty subjects (nine men and 41 women) with polyarthralgia who were suspected of having early-stage RA on the basis of clinical and radiographic findings were selected to undergo gadolinium-enhanced MR imaging of the hands. The MR imaging criterion for the diagnosis of early RA was bilateral enhancement in both wrists and/or the metacarpophalangeal and/or proximal interphalangeal joints. Follow-up continued until a final diagnosis was determined. Two patients left the study before the end of follow-up. RESULTS Final diagnoses were established after a mean follow-up of 776 days: rheumatoid arthritis in 26 patients and nonrheumatoid disease in 22. Use of the MR imaging criterion yielded the correct diagnosis in 25 patients with RA and three false-positive results in three patients without RA. As compared with the traditional format and classification tree criteria of the American Rheumatism Association, the MR imaging criterion allowed detection of seven and six additional patients with true RA, respectively. CONCLUSION The introduction of MR imaging into the diagnostic criteria for early RA may contribute to more accurate diagnosis in patients suspected of having RA and thus allow an earlier decision to start proper medication.