Power Doppler sonography in the diagnosis of hemophilic synovitis - a promising tool

Background: Recurrent hemarthroses in hemophilia results in synovitis and joint arthropathy. Primary prophylaxis when universally instituted at current doses can prevent joint deterioration but is expensive. Alternatively, the selective implementation of prophylaxis would require a more sensitive tool for detecting synovitis than possible with clinical surveillance or plain radiographs. Magnetic resonance imaging (MRI) is such a tool and is utilized for the evaluation of hemophilic joint disease (HJD). However, it is expensive, and requires sedation in younger children precluding its utility for monitoring of synovitis. Ultrasonography (USG) with power Doppler (USG-PDS) has been utilized to detect and quantitate synovial vascularity in other arthritides and could provide an equally effective but less costly tool for HJD, particularly in children who would not require sedation. Objectives: To determine whether USG-PDS is comparable to MRI in the evaluation of hemophilic synovitis. Patients: A prospective cohort of 31 subjects including 33 joints (knees, elbows, ankles) underwent dynamic contrast enhanced (DCE)-MRI and USG-PDS. Results: USG-PDS measurements of synovial thickness(r = 0.70, P < 0.0001) and synovial vascularity (r = 0.73, P < 0.0001) correlated strongly with those obtained with DCE-MRI. A cutoff of PDS intensity of 1.3 decibels (dB) per mm(2) was found to yield a sensitivity of 100% and a specificity of 94.1% in 17 joints with/without a history of hemarthroses. Pettersson radiographic scores correlated significantly with synovial thickness in adults but not children. Conclusions: Our data suggest that USG-PDS may be an inexpensive and easily implemented imaging tool for detecting hemophilic synovitis and could be useful in tailoring effective prophylaxis.