New radiographic bone erosions in the wrists of patients with rheumatoid arthritis are detectable with magnetic resonance imaging a median of two years earlier

Objective. In a 5-year followup study, we investigated the temporal relationship between development of wrist joint erosions as visualized by magnetic resonance imaging (MRI) versus conventional radiography (CR), in patients with rheumatoid arthritis. We also evaluated the risk of erosive progression on CR associated with the presence of MRI erosions. Methods. In 10 patients with rheumatoid arthritis, MRI and CR of the dominant wrist were performed annually for 5 years. In each image set, each wrist bone (metacarpal bases, carpal bones, radius, and ulna) was assessed for the absence or presence of bone erosions. Results. Nine bones showed radiographic erosions at baseline. Twenty-seven new radiographic erosions developed during the 5-year followup period. Of these 27 new erosions, 21 were detected 1-5 years earlier by MRI than by CR, 3 were simultaneously detected by both methods, 2 were detected 1-2 years later by MRI than by CR, and 1 erosion (radiographically detected at 5-year followup) was not visualized with MRI. MRI detection of new radiographic erosions preceded CR detection by a median of 2 years. In bones with MRI erosions at baseline, the relative risk of radiographic erosions at 5-year followup was 4.5 (95% confidence interval [95% CI] 2.6-7.6), compared with bones without baseline MRI erosions. If bones with baseline radiographic erosions were excluded from the analysis, the relative risk was 4.1 (95% CI 2.2-7.5). Conclusion. Most new radiographic bone erosions (78%) were visualized at least I year earlier by MRI than by CR. This illustrates that the information on joint destruction provided by CR is considerably delayed compared with that provided by MRI. A significantly increased risk of progression of radiographic erosion in bones with baseline MRI erosions was observed, demonstrating a prognostic value of MRI with respect to long-term radiographic outcome.