Validity of ultrasound arterial wall vascularization for assessment of vascular inflammation

Abstract

Abstract Background Vascular inflammation plays a fundamental role in most vascular diseases including atherosclerosis and vasculitis syndrome, in which arterial wall vascularization (AWV) frequently develops. Visualization of AWV is informative in detecting the vascular inflammation but is challenging. A new ultrasound technique (superb micro-vascular imaging [SMI]) allows the detection of extremely low-velocity flows. We examined an availability of SMI for assessment of the instability of atherosclerotic plaques and the activity of Takayasu arteritis (TA). Methods and results The study consists of two independent and consecutive parts A and B, examined in carotid stenosis (A) and TA (B), respectively. In part A, 12 patients with symptomatic severe carotid stenosis (CS group) scheduled for carotid endarterectomy were enrolled. In six of 12 patients, preoperative ultrasonography with SMI showed intraplaque neovascularization at the plaque shoulder. Postoperatively, histopathology confirmed the neovessels at the corresponding sites of visualized AWV. SMI had a sensitivity of 67%, specificity of 90% for detection of AWV in CS group. In SMI analysis, false positive findings were caused by motion artifact and arterial wall calcification, and a false negative finding is attributed by intraplaque hemorrhage. In part B, 10 patients with TA were enrolled. All patients underwent 18F-FDG-PET/CT, and its vascular uptake were compared with AWV detected by SMI. Bilateral common carotid arteries (CCA), internal carotid arteries and common iliac arteries were examined by SMI. Active vascular 18F-FDG uptake (max SUV >2.1) were found at five sites in three patients, which were not significantly correlated with the prevalence of macaroni sign, increase in C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). Of note, SMI revealed AWV at five sites corresponding to uptake of 18F-FDG, with a sensitivity/specificity of 100% and 98%, positive predictive value 71%, and a negative predictive value 100%. Conclusion SMI enables visualization of AWV at vulnerable plaque in CS patients and at 18F-FDG positive sites in TA patients. SMI has potential as a modality to detect the vascular inflammation. Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): Grant-in-Aid for Scientific Research, Japan