To study the ability of low-cost low-field dedicated extremity magnetic resonance imaging (E-MRI) to assess and predict erosive joint damage in the wrist and metacarpophalangeal (MCP) joints of patients with early rheumatoid arthritis.
24 previously untreated patients with rheumatoid arthritis with joint symptoms for <1 year were evaluated at the time of diagnosis and after 6 and 12 months of methotrexate treatment with conventional clinical or biochemical examinations, x rays of both hands and wrists, and E-MRI of the dominant wrist and MCP joints.
At baseline, all patients showed magnetic resonance imaging (MRI) synovitis, and MRI erosions were detected in 21 bones (10 patients). 6 (29%) of these, distributed among two patients, were seen on x ray. One x ray erosion was not detected by MRI. At 1 year, MRI and x ray detected 15 and 8 new erosions, respectively, and 19% of MRI erosions at baseline had progressed to x ray erosions. In bones with MRI erosions at baseline, the relative risk of having x ray erosions at the 1-year follow-up was 12.1, compared with bones without baseline MRI erosions (lesion-centred analysis). If bones with baseline x ray erosions were excluded, the relative risk was 5.2. In patients with baseline MRI bone erosion or oedema, the relative risk of having x ray erosions at 1 year was 4.0, compared with patients without these signs at baseline (patient-centred analysis).
In this group of patients with early rheumatoid arthritis who were treated uniformly, baseline E-MRI erosions in MCP or wrist bones markedly increased the risk of x ray erosions at the 1-year follow-up. Low-cost, low-field dedicated extremity MRI is promising for assessment and prognostication of early rheumatoid arthritis.