Power Doppler Sonography Is a Promising Imaging Tool in the Diagnosis of Hemophilic Synovitis - Preliminary Analyses.

Abstract

Hemarthrosis, a common manifestation of hemophilia, results in synovial proliferation leading to the development of synovitis, followed by arthropathy. Selective strategies like prophylaxis or isotopic synovectomy (IS) could be applied to prevent imminent joint deterioration but these are expensive, and their timing is unclear. Conventionally, synovitis was diagnosed based on clinical examination and radiography, which together tend to underestimate the extent of joint damage. Currently, magnetic resonance imaging (MRI) is utilized for the evaluation of cartilage and synovium in hemophilic joint disease (HJD). However, the need for sedation in younger children and high costs preclude its utility especially when frequent monitoring may be needed for management decisions. More recently, Power Doppler sonography (PDS) has been utilized to both detect and quantitate alterations in vascular flow in other arthritides. In the current study we compared findings obtained on PDS(using a Elegra scanner with a 7.5 MHz linear phased array transducer in tissue harmonic mode) in 12 subjects with HJD to MRI (using 3.0T GE scanner with dynamic gadolinium contrast enhanced perfusion studies and gradient echo sequence) as a reference standard. Clinical Joint scores were determined as per the Petrini Scoring system. Radiological Joint scores were as follows: No synovitis (0), mild (1), moderate (2) and intense (3). Our preliminary analyses showed that MRI and PDS could detect increased vascularity of the synovium in all subjects with clinically active synovitis (6/12) and that Clinical Joint scores correlated with Synovitis scores on MRI and PDS. Further, synovial thickness, vascularity of synovium defined as enhancement on post-contrast MRI (MRI flow) and pixel count on PDS (PDS flow) correlated significantly between the two methods - Table 1. We previously observed that HJD subjects have significantly elevated levels of angiogenic markers such as vascular endothelial growth factor (VEGF) as compared to controls thus implicating VEGF as a serological marker for synovitis. Acknowledging the fact that PDS detects flow at the microvascular level we further observed that subjects with increased synovial vascularity showed significant positive correlations with VEGF levels - Table 1. Hence, our data suggest that PDS in children may be a promising and inexpensive imaging tool in diagnosing synovitis associated with HJD. It could be potentially used as a screening tool after one or two joint bleeds to monitor for the development of early synovitis and aid in tailoring prophylaxis. Based upon these preliminary analyses, correlation of data obtained from PDS with serological markers of angiogenesis may further aid in predicting joint disease activity.ComparisonMRIPDSp-valueClinical Joint Score (Petrini)1.54 (synovitis score)0.01*Clinical Joint Score (Petrini)1.46 (synovitis)0.04*Mean Synovial Thickness (cm)4.777.970.03*Flow (Vascularity)138.10 (pce**)9.22 (pixel count)0.009*Mean Synovial Thickness vs. Flow***0.12Mean Synovial Thickness vs. Flow***0.02*VEGF Levels vs. Flow***0.03*VEGF Levels vs. Flow***0.049** p-values < 0.05 are significant as assessed by Spearman rank correlation coefficient; ** pce = post contrast enhancement; *** Synovial Thickness or VEGF Levels compared to indicated imaging technique