Magnetic Resonance Imaging of the Synovium in Rheumatoid Arthritis

Abstract

Early diagnosis, followed by early initiation and optimal adjustments of aggressive therapies, are acknowledged as essential to optimize long-term clinical and radiological outcome in rheumatoid arthritis (RA). This requires sensitive methods for detection and monitoring of the primary feature of RA--the synovitis. In comparison with conventional methods, magnetic resonance imaging (MRI) offers assessment of the rheumatoid synovium with improved sensitivity to early pathology and to change. Various aspects such as volume, vascularity, and edema can be assessed by different metrological approaches. MRI findings are of prognostic value to the long-term radiological outcome. This article reviews current knowledge on MRI for assessment of the synovium in RA, focusing on the validity of MRI measures of synovitis. Future perspectives and suggested research priorities are described. The rationale is provided for MRI becoming the new gold standard for assessment of RA joints and for MRI assessments of synovitis being reliable and valid measures of rheumatoid disease activity.

Imaging of non-osteochondral tissues in osteoarthritis

“…MRI signs of synovitis are related to increased thickness/volume, increased signal intensity after intravenous gadolinium injection ("enhancement"), and increased water content, alone or in combination 24 . The importance of deploying CE-MRI for assessment of synovitis in OA has recently been recognized 9 .…”

“…Although non-CE-MRI is still the most commonly used modality to assess synovitis in OA clinical studies 24,25,37,38 , findings from CE-MRI studies have demonstrated the limitations of non-CE-MRI for evaluation of synovitis 11e13,20,23,36,39e43 . One clear advantage of CE-MRI over non-CE-MRI is its ability to differentiate inflamed synovium from joint effusion.…”

“…There are few studies using dynamic CE-MRI, in which early enhancement (i.e., initial distribution of gadolinium) accurately reflects the inflammatory activity of the joint 24,55,56 . With static CE-MRI, the extent of "synovial enhancement" may be misinterpreted if the assessment is performed on images acquired at a late phase, because the signal intensity of joint effusions also increases with time, starting in the periphery and gradually approaching the central parts, as gadolinium passes into the joint space by diffusion of fluid from synovial capillaries 27 .…”

Prediction of radiographic progression in synovitis-positive joints on maximum intensity projection of magnetic resonance imaging in rheumatoid arthritis

“…For this reason, magnetic resonance imaging (MRI) and ultrasonography (US) are now used for synovitis evaluation in RA [2,3]. These diagnostic imaging techniques are useful for early diagnosis and prediction of joint destruction, because they are able to identify synovitis with greater sensitivity and accuracy than physical findings [4][5][6].…”

Maximum intensity projection as a tool to diagnose early rheumatoid arthritis

“…The validity of MRI in diagnosing early RA is improving, since it shows greater sensitivity than radiography in detecting synovitis [6,14,15]. However, evaluations based on MRI images are occasionally difficult and time consuming.…”