Assessment of synovitis in rheumatoid arthritis by enhanced magnetic resonance imaging (OMERACT RAMRIS score) and power Doppler ultrasound: a comparative study

Background and objectives: Disease activity in rheumatoid arthritis (RA) joints is conventionally assessed clinically in combination with the measurement of levels of biochemical surrogate markers. Plain radiography shows only late signs of preceding disease activity. Newer imaging modalities such as contrast-enhanced MRI and power Doppler ultrasonography (PDUS) may offer improved monitoring. The aim of the study was to compare the role of PDUS with enhanced MRI in the assessment and scoring of synovitis of the wrist and hand joints in RA patients. Patients and methods: Fifty patients (39 female patients and 11 male patients) with RA were subjected to a PDUS study and enhanced MRI examination of the clinically dominant wrist and hand joints. The mean age of the patients was 45.3 years and mean disease duration was 6.2 years. Power Doppler score of synovitis was correlated and compared with MRI OMERACT score. Results: PDUS detected increased vascularity within 30 (60%) wrist joints denoting active synovitis and MRI detected synovial enhancement within 38 (76%) wrist joints denoting active synovitis; both scoring systems agreed in the assessment of synovitis degree in 20 wrist joints. PDUS missed detection of synovitis in nine joints detected by MRI, seven of them estimated by MRI to be of mild activity (grade 1). PDUS detected synovial activity (increased vascularity) in metacarpophalangeal (MCP) joints of 21 patients, whereas MRI detected synovial activity (synovial enhancement) in MCP joints of nine patients. Both modalities agreed in eight patients as regards the total synovial activity score. Statistical analysis of these results showed a statistically significant correlation (P 0.001) and good agreement between the two modalities in the assessment of synovial activity in the wrist and MCP joints. Comparison of ultrasonography and MRI yielded a κ value of 0.482 and 0.376, respectively. Conclusion: Our results showed that both modalities are comparable and closely related in the assessment of synovial inflammatory process of the hand and wrist joints in RA patients.