Magnetic resonance imaging (MRA) greatly improves the early detection and visualization of osseous and non-osseous joint changes over conventional x-rays of involved joints in patients with rheumatoid arthritis (RA). However, the "pathophysiological correlate" of these MR imaging changes remains poorly defined. Careful validation of MRI findings and the evaluation of MRI as a tool to follow the effect of therapy remain to be performed before MRI may be used as a clinical tool to follow therapy or as a surrogate for evaluating osseous changes over time.