New quantification methods for carotid intra-plaque neovascularization using contrast-enhanced ultrasound

Abstract

As carotid intra-plaque neovascularization (IPN) is linked to progressive atherosclerotic disease and plaque vulnerability, its accurate quantification might allow early detection of plaque vulnerability. We therefore developed several new quantitative methods for analyzing IPN perfusion and structure. From our analyses, we derived six quantitative parameters-IPN surface area (IPNSA), IPN surface ratio (IPNSR), plaque mean intensity, plaque-to-lumen enhancement ratio, mean plaque contrast percentage and number of micro-vessels (MVN)-and compared these with visual grading of IPN by two independent physicians. A total of 45 carotid arteries with symptomatic stenosis in 23 patients were analyzed. IPNSA (correlation r = 0.719), IPNSR (r = 0.538) and MVN (r = 0.484) were found to be significantly correlated with visual scoring (p < 0.01). IPNSA was the best match to visual scoring. These results indicate that IPNSA, IPNSR and MVN may have the potential to replace qualitative visual scoring and to measure the degree of carotid IPN.

Keywords: Carotid plaque; Contrast agents; Contrast-enhanced ultrasound; Microbubbles; Microvessels; Plaque neovascularization; Quantification; Vasa vasorum.