Objective: The aim of this study was to evaluate both the performance characteristics of magnetic resonance imaging (MRI) in the differential diagnosis of monoarthritis of the wrist and the predictive ability of the 1987 American College of Reumatology (ACR) and 2010 ACR/European League Against Rheumatism (EULAR) criteria. Methods: The 29 patients with monoarthritis of the wrist retrospectively reviewed in this study underwent preoperative MRI with or without a white blood cell (WBC) scan. Their diagnoses were confirmed histologically after open synovectomy. Synovitis, bone erosion, and bone edema, as seen on MRI, were measured by 2 readers independently using the Outcome Measures in Rheumatology Clinical Trials (OMERACT) Rheumatoid Arthritis Magnetic Resonance Imaging Score (RAMRIS) system. Receiver operating characteristic (ROC) curves were used to calculate the cutoff differentiating rheumatoid arthritis (RA) from other diseases. The optimized cutoff point for each parameter was determined using Youden index. Results: The areas under the ROC curves for the synovitis, bone erosion, and bone edema scores were 0.892, 0.853, and 0.752, respectively. The cutoff values of these scores to predict RA were 5, 48, and 19, respectively. The sensitivity and specificity of the 1987 ACR criteria were 50% and 92% and those of the 2010 ACR/EULAR criteria were 60% and 75%. Conclusion: The OMERACT RAMRIS system provides a valuable tool to differentiate RA from tuberculosis and undifferentiated chronic monoarthritis in patients with wrist monoarthritis. A multimodal diagnostic approach using MRI, WBC scan, and histologic evaluation is recommended if the diagnosis cannot be established based on clinical, biochemical, and radiographic evaluations.
