Ultra-microangiography (UMA) is a novel Doppler technique that has high sensitivity for low-velocity blood flows. In this study, a distinctive imaging feature, penetrating blood vessels on the surface of eroded bones within the inflamed joints, was observed on UMA. We aimed to investigate the feasibility of UMA in assessing disease activity and identify the clinical value of the UMA feature for evaluating rheumatoid arthritis (RA).
Power-Doppler ultrasound (PDUS) and UMA were performed on small joints of RA patients. The semiquantitative scores of PDUS and UMA of the joints were assessed and compared. The UMA imaging feature of penetrating vessels on the surface of eroded bones was evaluated, and the patients were divided into three groups based on imaging features. (Group 1: no inflammatory signs; Group 2: inflammatory US features but no UMA features; and Group 3: detected UMA features). The correlations between the groups and clinical parameters were assessed.
A total of 52 patients with RA were recruited, with 364 joints (MCP, PIP, MTP and wrist) scanned. Synovial blood vessel signals were detected for 68 by PDUS and for 93 by UMA (display rate of blood vessel signals: 18.68 % VS 25.55 %). UMA presented better display capability of blood vessels within the inflamed regions than that of PDUS in overall. Significant differences were detected in clinical scores (P < 0.0001 for DAS28 [ESR], DAS28 [CRP], SDAI, CDAI, CRP P = 0.0303, SJC P = 0.0059, and TJC P = 0.0423) between Group 2 and 3. Significant correlations between the groups and clinical parameters were also observed (DAS28 [ESR] ρ=0.750; DAS28 [CRP] ρ=0.762; SDAI ρ=0.778; CDAI ρ=0.773; CRP ρ= 0.524; SJC ρ=0.742; TJC ρ=0.693, P < 0.0001), indicating that the UMA feature was related to high disease activity.
UMA can help enhance the detection rate of micro-vascularization. The UMA feature of the penetrating vessels on the surface of eroded bones is likely to be associated with severe disease activity.