Doppler ultrasound and magnetic resonance imaging of synovial inflammation of the hand in rheumatoid arthritis - A comparative study

Objective. To compare the quantitative and qualitative information obtained by Doppler ultrasound (US) measurements of the wrist joints and the small joints of the hand with the information obtained by postcontrast magnetic resonance imaging (MRI) and to correlate the imaging results with clinical observations in patients with rheumatoid arthritis (RA). Methods. Twenty-nine consecutive RA patients were studied; 196 joints (29 wrist and 167 finger joints) were examined by both US and MRI. Parameters of inflammation were the color fraction and the resistance index (RI) obtained with color Doppler US and the thickness of enhanced synovium (in mm) and the MRI score obtained with postcontrast MRI. Clinical examination and measurements of the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) level were performed on the same day as the imaging studies. Results. There was a highly significant association between US indices of inflammation and postcontrast MRI scores. The mean values for both the color fraction and the RI were significantly different in the group without joint swelling compared with the other groups. The mean RI values were significantly different in the group without joint tenderness compared with the other groups. The mean thickness of enhanced synovium on postcontrast MRI was significantly different between the group without joint swelling and the other groups, but this difference was statistically significant only for the comparison of the group without joint tenderness versus the group with maximum tenderness. No association between the MRI or US estimates of inflammation and values on the visual analog scale for pain, Health Assessment Questionnaire, duration of morning stiffness, ESR, or CRP was found. Conclusion. Estimates of synovial inflammatory activity by Doppler US and postcontrast MRI were comparable. Estimation of synovial inflammatory activity by the RI and color fraction parameters of US appears to be a promising method of detecting and monitoring inflammatory activity in patients with RA.