Power Doppler and spectral Doppler measurements of knee-joint synovitis in rheumatoid arthritis patients with superficial pattern signals and in those with deep pattern signals

Abstract

Power Doppler and spectral Doppler ultrasonography were used to scan 127 knee joints of 72 patients with rheumatoid arthritis (RA). Synovial effusion thickness and synovial proliferation (pannus) thickness, as well as the flow signal diameter, were measured on ultrasonogram prints of the power Doppler using digital calipers. In addition, color-flow signal grades on power Doppler and the resistance index (RI) values on spectral Doppler were evaluated. The values of these five variables were compared among 58 joints with superficial pattern flow signals and 69 joints with deep pattern flow signals. Compared with the joints with deep pattern signals, the joints with superficial pattern signals had significantly higher mean values of effusion thickness (P < 0.0001) and flow signal grades (P < 0.0001), and significantly lower mean RI (P < 0.0001). On the other hand, the joints with deep pattern signals had a significantly higher value of signal diameter (P = 0.0125) and had a trend to higher value of pannus thickness (P = 0.079) as well. Significant correlations were observed between effusion thickness and signal grades (P < 0.0001); effusion thickness and RI (P < 0.0001); signal diameter and pannus thickness (P = 0.0102); signal diameter and RI (P < 0.0001); and signal grades and RI (P < 0.0001). The ultrasonographic measurements of synovitis in RA patients provide valuable information on synovial inflammation.