A multicenter reliability study of extremity-magnetic resonance imaging in the longitudinal evaluation of rheumatoid arthritis.

There are limited data on the reliability of extremity magnetic resonance imaging (E-MRI) in the longitudinal evaluation of rheumatoid arthritis (RA). Our aim was to assess the interreader reliability of the OMERACT RA MRI score in the assessment of change in disease activity and bone erosion scores using 0.2 T E-MRI hand and wrist images from 2 timepoints, evaluated by 3 readers at different international centers. The intraclass correlation coefficients and smallest detectable difference results for the change scores were generally good for erosions and synovitis, but were not acceptable for bone edema. Overall, E-MRI demonstrated ability to detect change comparable to that reported for high-field MRI for erosion and synovitis.