EUROPEAN ALLIANCE OF ASSOCIATIONS FOR RHEUMATOLOGY (EULAR) Early inflammatory arthritis is often undifferentiated, but it may develop into established RA or another arthropathy.1 Alternatively, it may resolve spontaneously, or remain undifferentiated for indefinite periods. Erosion is a key prognostic factor which can be detected with magnetic resonance imaging (MRI).2 In addition, MRI allows direct visualization...