Ultrasonographic evaluation of joint involvement in rheumatoid arthritis: Comparison with conventional radiography and correlation with disease activity parameters

Abstract

Background: Ultrasound (US) including power Doppler (PD) are increasingly being used to evaluate joint involvement in rheumatoid arthritis (RA). Aim of this study was to evaluate joint involvement in RA by US including PD and gray scale imaging and its comparison with conventional radiographic changes and correlation with disease activity parameters. Methods: Patients with RA of less than 3.5 years disease duration were subjected to detailed clinical examination and laboratory investigations. After X-ray imaging (posterior-anterior view) of both hand joints, PD and gray scale US examination of 14 joints of both hands was performed and mean cumulative flow signal score (CFS) was calculated. Disease activity score (DAS28) was also calculated for each patient. Results: Out of total 57 patients evaluated, 54 had abnormal findings on US as compared to only 17 having radiographic abnormalities. US could detect erosions in 29 patients including all of the fourteen patients who had radiographically detectable erosions. On US evaluation, radiocarpal joint was involved most frequently. The mean CFS was 1.17 ± 1.64 in patients who were in remission (DAS28 <2.6), 3.00 ± 3.46 in patients having low disease activity (DAS28 2.6-3.2), 5.25 ± 4.22 in patients with moderate disease activity (DAS28 3.2-5.1), and 6.95 ± 3.84 in patients with high disease activity (DAS28 > 5.1). The difference in CFS among these groups was statistically significant (P < 0.01). In 5 out of 12 patients with DAS28 <2.6, i.e., in remission, CFS were high showing subclinical synovitis. Mean CFS correlated significantly with DAS28 (r = +0.42, P < 0.05); C-reactive protein (r = +0.50, P < 0.05); and erythrocyte sedimentation rate (r = +0.39, P < 0.05). Conclusions: US detected CFS which an indicator of ongoing inflammation in RA patients with clinical remission (DAS28 <2.6). US is more sensitive than conventional radiography for detection of erosions. CFS on PD had a significant correlation with markers of disease activity.