Correlation of power Doppler sonography with vascularity of the synovial tissue of the knee joint in patients with osteoarthritis and rheumatoid arthritis

Objective. To examine the significance of power Doppler sonography (PDS) in the diagnosis of synovial hypertrophy of the knee joint by verifying and c omparing the PDS findings with histopathologic findings of synovial membran e vascularity. Methods. The knee joints of 23 patients who were undergoing arthroplasty of the knee joint because of osteoarthritis or rheumatoid arthritis were exam ined with ultrasound before arthroplasty. The vascularity of the synovial m embrane was classified semiquantitatively using PDS. A sample of synovial t issue was obtained during the arthroplasty, and the vascularity of the syno vial tissue was evaluated by immunohistochemistry (factor VIII) and was gra ded qualitatively by a pathologist who was unaware of the PDS findings. The visual qualitative grading by the examiner was controlled by analyzing PDS images and histologic samples using a digital image evaluation system. Results. The correlation between the qualitative PDS results and the qualit ative grading of the vascularity by the pathologist was 0.89 by Spearman's rho (P < 0.01). The Pearson correlation coefficient between the digital ana lysis of the PDS images and the digital analysis of the tissue sections was 0.81 (P < 0.01). Digital image analysis and qualitative grading by the exa miner had a correlation of 0.89 by Spearman's rho (P < 0.01) for the PDS im ages. The correlation between the qualitative estimation of vascularity by the pathologist and the digital image analysis was 0.88 by Spearman's <rho> (P < 0.01). Conclusion. In the present study, PDS proved to be a reliable diagnostic me thod for qualitative grading of the vascularity of the synovial tissue. In clinical practice, PDS allows further differentiation of the hypertrophic s ynovium.