Established rheumatoid arthritis - new imaging modalities.

New imaging modalities are assuming an increasingly important role in the investigation and management of rheumatoid arthritis. It is now possible to obtain information about all tissues within the joint in three dimensions using tomographic techniques such as magnetic resonance imaging (MRI) and high-resolution computerized tomography. Erosions are very clearly depicted using these modalities and MRI also allows imaging of soft tissues with assessment of joint inflammation. High-resolution ultrasound is a convenient clinical technique for the assessment of erosions, synovitis and tenosynovitis in real-time and facilitates diagnostic and therapeutic interventions such as joint aspiration and injection. Exciting experimental modalities are also being developed with the potential to provide not just morphological but functional imaging. Techniques such as positron emission tomography (PET) and single photon emission tomography (SPECT) can reveal actively metabolizing bone and the proliferation of synovial cells via radioactive labeling. Bioluminescence and fluorescence reflectance imaging are other approaches that allow imaging, and potentially the delivery of therapeutic agents, at a molecular level.