Reliability of Magnetic Resonance Imaging (MRI) Scoring of the Metatarsophalangeal Joints of the Foot according to the Rheumatoid Arthritis MRI Score

Objective. The Rheumatoid Arthritis Magnetic Resonance Imaging Score (RAMRIS) is validated for hand MRI. Its reliability applied to metatarsophalangeal (MTP 1–5) joints is unknown and was studied in early arthritis and clinically suspect arthralgia.

Methods. Patients underwent 1.5 Tesla MRI of MTP, metacarpophalangeal (MCP 2–5), and wrist joints. Two paired readers scored bone marrow edema (BME), synovitis, tenosynovitis, and erosions. Interreader reliability was assessed of 441 consecutive early arthritis patients at baseline, 215 by 2 readers, and the remaining 226 by 2 different readers. Two readers scored baseline MRI of 82 consecutive patients with clinically suspect arthralgia, and 40 randomly selected patients by 9 readers. Intrareader reliability was determined on a random set of 15 early arthritis patients, scored twice by 2 readers. For change scores, 30 early arthritis patients with baseline and 1-year followup MRI were scored by 2 readers. Intraclass correlation coefficients (ICC), Bland-Altman (BA) plots, and smallest detectable change (SDC) were determined. MRI data of MTP joints were compared to wrist and MCP joints.

Results. Interreader ICC and mean scores in early arthritis were BME ICC 0.91–0.92 (mean 1.5 ± SD 2.6), synovitis 0.90–0.92 (1.3 ± 1.7), tenosynovitis 0.80–0.85 (1.1 ± 1.8), and erosions 0.88–0.89 (0.7 ± 1.0). In patients with clinically suspect arthralgia, ICC were comparable. Intrareader ICC for inflammatory MRI features were 0.84–0.98, for erosions 0.71 (reader 1), and 0.92 (reader 2). Change score ICC were ≥ 0.90, except erosions (0.77). SDC were ≤ 1.0. BA plots showed no systematic bias. Reliability scores of MTP joints were similar to MCP and wrist joints.

Conclusion. Status and change MRI scores of BME, synovitis, tenosynovitis, and erosions of MTP joints can be assessed reliably by RAMRIS.