Quantitative ultrasonography in rheumatoid arthritis: evaluation of inflammation by Doppler technique

Objective-To evaluate ultrasonographic methods, including the Doppler techn ique, as measures of synovial inflammation in finger joints of patients wit h rheumatoid arthritis. Methods-ultrasonography was performed with a high frequency transducer (13 MHz). Evaluation of the sonographic data was conducted by two independent o bservers and included measurement of synovial area and thickness (grey tone ultrasound), vascularisation (power/colour Doppler), and indices of the in tra- and extrasynovial arterial flow (spectral Doppler). The flow pattern w as estimated by the indices of pulsatility (PI) and resistance (RI). Results-The sonographic measurements of joint space were reproducible with intraobserver, intraclass correlation coefficients (ICC) 0.82-0.97 (p<0.000 1) and interobserver ICC 0.81 (p<0.0001). The mean (SI) fraction of the syn ovium vascularised in the patients was 0.15 (0.15). The synovial blood flow was characterised by a diastolic flow-that is, the flow persisting during the diastole. The mean (SD) PI was 1.92 (1.18) and RI 0.70 (0.13). The esti mated vascular fraction correlated with the erythrocyte sedimentation rate (ESR) (r(s)=0.53, p=0.03). The relative Pi (rPi), an estimate of an abnorma lly low resistance to vascularisation, correlated with both ESR (r(s)=-0.55 7, p<0.05) and Health Assessment Questionnaire score (r(s)=-0.584, p<0.05). After an injection of contrast Levovist the vascular fraction increased, w hile no difference in PI and RI was observed. Conclusion-Ultrasonography is a reliable tool for estimating the size of th e joint space and the synovial activity measured by the degree of vasculari sation and pattern of flow. Ultrasonography may be useful in monitoring the synovial inflammation in rheumatoid arthritis.