Imaging in rheumatoid arthritis - why MRI and ultrasonography can no longer be ignored

Implementing the modern treatment strategy in rheumatoid arthritis (RA), i.e. early initiation and optimal adjustments of aggressive therapies, requires methods for early diagnosis and sensitive monitoring of the disease process. In rheumatoid arthritis clinical trials and routine management, conventional radiography is the pivotal method for diagnosing and monitoring structural joint damage. However, it is insensitive to bone damage at its earliest stages and totally incapable of capturing the primary feature of rheumatoid disease, the synovitis. In comparison with radiography, magnetic resonance imaging (MRI) offers assessment of bone damage with improved sensitivities to early pathology and to change. In addition, detailed assessment of soft tissue changes, including synovitis and tenosynovitis, is possible and MRI findings are of prognostic value for the long-term radiological outcome. Ultrasonography (US) is less validated than MRI, but available data suggests that US offers comparable information on both inflammatory and destructive changes in RA finger and toe joints. Issues of reliability, standardization and documentation limit its value in clinical trials, This article reviews current knowledge on conventional radiography, computed tomography, MRI and US for assessment of peripheral joints in RA. The rationale is provided for MRI being the new gold standard for assessment of RA joints and US becoming a routine bedside tool for improved joint assessments and injections by rheumatologists. Pursuing the goal of improving patient care and disease outcome, rheumatologists can no longer afford to ignore MRI and US as means to measure disease activity and joint damage in rheumatoid arthritis.