Advances in ultrasound (US) and magnetic resonance imaging (MRI) techniques have provided new methods for evaluating early rheumatoid arthritis (RA). Their diagnostic properties in terms of detecting primary pathology of RA (i.e., erosions, bone changes, synovitis, tenosynovitis, and effusion) are reviewed. High-resolution US plays a significant role in therapeutic and diagnostic procedures. MRI also assists in the understanding of RA pathogenesis and joint mechanics.
