Background Musculoskeletal ultrasonography (US) has been routinely used to confirm synovial effusion in children with arthritis. Recent studies show that US is more sensitive than clinical examination in detecting synovitis in juvenile idiopathic arthritis (JIA). In addition, given the high sensitivity of US in detecting subclinical synovitis, minimal effusion or even age-related variations, it remains important for the interpretation of US abnormalities in the clinical context. Since mostly data focusing on US detection of JIA synovitis include grey-scale (i.e. B-mode) US, the actual significance of US-detected subclinical synovitis in asymptomatic joints remains unclear.
Objectives To investigate the usefulness of ultrasonography with power Doppler (PDUS) for detecting synovitis compared with clinical examination on large number of joints in JIA.
Methods This multicenter study included 42 children with active JIA. Clinical and PDUS assessments were performed blindly on 44 joints. Active disease was defined by high acute phase reactants with clinically active arthritis. Active arthritis on US was defined as synovial hypertrophy, effusion, or increased vascularity on power Doppler (PD) scan. For the US-image analysis the OMERACT definitions for Rheumatoid Arthritis of synovitis was applied . McNemar test was used to compare the percentage of joints showing synovitis detected by clinical examination and by PDUS.
Results In total, 1848 joints were examined both clinically and by PDUS. Physical examination showed 277 joints (15.0%) having clinically active synovitis, and of these, 184 (10%) had synovitis confirmed by US. Furthermore, up to 177 joints (9.6%) were shown to have synovitis on US examination alone. The percentage of joints with synovitis confirmed by PDUS (19.5%, n=361 joints) was statistically higher than the percentage of joints having clinically active synovitis, 15.0% (p < 0.0005). Of the 361 joints with GS synovitis detected by US examination, 116 (32.1%) joints were shown to have inflammatory activity by PD signal detected in SH. Subclinical active synovitis was confirmed by PDUS in 51/177 joints (28.8%) that only seemed to have synovitis on US examination.
Conclusions The study shows that the PD-technique along with GS examination increases the sensitivity of US for detecting subclinical synovitis in JIA. However, longitudinal studies in children are required to know subsequent structural damage.
Wakefield RJ, Balin PV, Szkudlarek M et al. OMERACT 7 Special Interest Group: Diagnosed musculoskeletal ultrasound including definitions for ultrasonography patology. J Rheumatol 2005;32:2485-2487
Disclosure of Interest None Declared