Early diagnosis and treatment have been recognized as essential for improving clinical outcomes in patients with rheumatoid arthritis (RA). Magnetic resonance imaging (MRI) is a sensitive modality that can assess both inflammatory and structural lesions. MRI can assist in following the disease course in patients treated with traditional disease-modifying antirheumatic drugs and biological therapies both in the clinic and in research trials. Therefore, it is anticipated that MRI becomes the diagnostic imaging modality of choice in RA clinical trials while remaining a useful tool for clinicians evaluating patients with RA.
More sensitive imaging techniques were incorporated in the assessment of early aggressive rheumatoid arthritis (RA) because of the availability of effective biological therapies.
Distinguishing between active treatments in modern trials is difficult using conventional radiography and is especially limited in early disease detection.
Magnetic resonance imaging has the advantage of detecting both joint inflammation and damage and thus provides additional and unique data.
This information is useful for early and accurate diagnosis, prediction of poor prognosis, and monitoring response to therapy in RA clinical trials.
More recently, attention has been focused on how early the active treatment of RA should be initiated. Finckh and colleagues demonstrated that a shorter disease duration is the strongest predictor of improvement in disease activity over 5 years, and delayed treatment led to further radiographic progression. Bathon and colleagues administered etanercept to patients within 1 year of onset of RA and reported that the bone erosion score showed a significantly slower rate of change in the etanercept group than in the methotrexate (MTX) group. Nell and colleagues prospectively investigated the changes of disease activity (Disease Activity Score [DAS] 28) in patients with early RA (<3 months). The group reported that DAS28 improved significantly after 3 months of disease-modifying antirheumatic drug (DMARD) therapy; this trend continued over the following 3 years. Others have placed increasing emphasis on assessing and diagnosing RA within the first 6 weeks of patient symptoms, initiating treatment using DMARD therapy in a similar time frame. This is reflected in both the European League Against Rheumatism (EULAR) and the American College of Rheumatology (ACR) guidelines for patient care.
The availability of DMARDs, including biological therapy for early aggressive RA, generated the need for more sensitive imaging techniques. These give further insight into the underlying pathophysiology of RA and assist the clinician in predicting prognosis and monitoring long-term treatment. Thus, an accurate early diagnosis of RA assisted by detailed joint imaging may be especially beneficial in preventing disability.
Limitations of radiography in RA
The first study comparing magnetic resonance imaging (MRI) and radiography of the wrist joint in patients with RA was published in 1988. There have been numerous subsequent publications using MRI in RA that have demonstrated the technique’s utility in detecting early arthritic changes. Many studies have compared the sensitivity of detecting bone erosions between MRI and conventional radiography. In addition, longitudinal studies have confirmed that many bone marrow lesions (osteitis) seen with MRI progress to radiographic erosions. Thus, in addition to lacking the capacity for multidimensional imaging (2-dimensional representation of 3-dimensional pathologic condition), radiographs do not detect early bone lesions because they are incapable of assessing osteitis ( Figs. 1–3 ).