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.