OMERACT Rheumatoid Arthritis Magnetic Resonance Imaging Studies. Summary of OMERACT 6 MR Imaging Module

Magnetic resonance image (MRI) scanning is a new method for imaging and quantifying joint inflammation and damage in rheumatoid arthritis (RA). Over the past 4 years, the OMERACT MR Imaging Group has been developing and testing the RA-MRI scoring system (RAMRIS) for use in RA. The OMERACT filter demands that an ideal outcome measure satisfy the elements of truth, discrimination, and feasibility. The RAMRIS as it currently stands incorporates measures of joint inflammation and damage including bone erosion, edema, and synovitis. Tendonitis has not been scored because of feasibility issues; joint space narrowing, reflecting cartilage damage, has also been excluded as reliability was low at the small joints of the hands. Anatomical coverage of the score is currently restricted to the wrists and hands but can provide a basis for a more comprehensive score. The MR measurement of synovitis correlates closely with histological evidence and work continues on validating MR erosions with reference to radiographic techniques. The RAMRIS has demonstrated good reliability for bone erosion and synovitis at the wrists and metacarpophalangeal joints subject to reader training, with slightly lower levels of reader agreement for bone edema. Reliability was less satisfactory in discriminating between 2 time points, and further work is required if the score is to be used to monitor change. Feasibility also needs to be considered for the practical application of the score, including the time taken for scanning and scoring, as well as cost and safety issues. The OMERACT RAMRIS provides a framework for scoring inflammation and damage in RA upon which further modifications can be built. It has been endorsed by the MRI working group and OMERACT 6 participants as useful for inclusion as an outcome measure in clinical trials.