Magnetic resonance imaging of the rheumatic foot according to the RAMRIS system is reliable

In rheumatology, magnetic resonance imaging (MRI) is predominantly applied in the assessment and outcome measurement of rheumatoid arthritis (RA) in hands and wrists, leading to the development of the RAMRIS (RA-MRI-Scoring) system. It was initiated by the Outcome Measures in Rheumatoid Arthritis Clinical Trials (OMERACT). The RAMRIS system has not been applied widely in the measurement of feet. We investigated the interreader and intrareader agreement of the RAMRIS scoring system in the assessment of feet in RA.

Twenty-nine patients with RA who had radiological damage and/or arthritis underwent MRI. Two experienced readers independently read both complete sets. One reader read 6 random sets after the initial session, in order to assess the intrareader agreement. For evaluation of the intrareader and interreader reliability, quadratic-weighted κ scores were calculated per joint and lesion.

For the forefeet, interreader scores were excellent, ranging from 0.77 (bone edema) to 0.95 (bone erosion). Hindfoot interreader agreement scores were highest for erosion (0.90) and synovitis global score (0.88), but edema and synovial thickness agreement were also acceptable (0.83 and 0.86). Intrareader scores were on the whole slightly lower, but excellent.

Reliability (interreader and intrareader agreement) in the assessment of the rheumatoid foot according to the RAMRIS method is excellent.