To assess the practical usefulness of magnetic resonance imaging (MRI) in establishing a positive diagnosis of rheumatoid arthritis (RA) in a cohort of patients with early inflammatory polyarthralgia, in the absence of anti-cyclic citrullinated peptide (anti-CCP) antibodies.
We prospectively followed 30 outpatients with inflammatory polyarthralgia and/or synovitis of at least one joint. Patients were disease modifying antirheumatic drug-naive and received no corticosteroids. At the initial visit a clinical examination, radiographs of hands, wrists and feet, and MRI of hands were performed. Rheumatoid factor and anti-CCP antibodies were assessed. The MRI procedure was T1 fat saturation with gadolinium injection [scores were established on the basis of the axial view of the carpal and metacarpal joints, using the RA MRI scoring system (RAMRIS) defined in the OMERACT study]. In all patients, radiographs at baseline were normal and anti-CCP antibodies were negative.
At one-year followup, the final diagnosis was: 16 RA; the non-RA group was composed of 4 cases of spondyloarthropathy, 2 cases of fibromyalgia, 4 cases of undifferentiated arthritis (3 of which were self-limiting), 1 sicca syndrome, 1 hemochromatosis, 1 polymyositis, and 1 paraneoplastic syndrome. No statistical difference was found between patients with and without RA for carpal erosion, synovitis, and tenosynovitis. However, a statistical difference was observed between the RA and non-RA group where metacarpophalangeal (MCP) erosion scores were concerned (p = 0.024). This difference persisted when we compared erosions of the second and third MCP in the 2 groups (p = 0.044). ROC curve analysis revealed a positive MCP score at 15, with a specificity of 70% and a sensitivity of 64%.
In our population of 30 anti-CPP negative patients with normal radiographs, MRI of hands, showing MCP erosions, can be helpful for the diagnosis of RA.