Computer-assisted Ultrasound Assessment of Plaque Characteristics in Radiation-induced and Non-radiation-induced Carotid Atherosclerosis

Abstract

Background Carotid atherosclerosis is common in post-radiotherapy (post-RT) patients and subjects with cardiovascular risk factors (CVRFs). The associated development of carotid plaques (CPs), particularly unstable plaques, is a major cause of cerebrovascular disease. Therefore, accurate detection and evaluation of CP characteristics is of essence. This study investigated the feasibility of using a computer-assisted method to evaluate and differentiate the CP characteristics in radiation-induced and non-radiation-induced CA. Methods 107 post-RT NPC and 110 CVRF subjects were recruited. Each participant had a carotid ultrasound examination of CPs and carotid intima-media thickness (CIMT). The carotid plaque characteristics were evaluated for grey-scale median (GSM) and detailed plaque texture analysis (DPTA) using specific computer software. In DPTA, five different intra-plaque components were color-coded according to different grey scale ranges. Multivariate regression model was used to evaluate the correlation of risk factors and carotid plaque characteristics. Results Post-RT NPC patients have significantly higher CIMT (748±15.1µm, p=0.001), more incidence of plaque formation (80.4%, p<0.001) and larger number of plaques (2.3±0.2, p<0.001) than CVRF subjects (680.4±10.0µm, 38.2% and 0.5±0.1 respectively). Among the five intra-plaque components, radiation-induced carotid plaques had significantly larger area of calcification (4.8 ±7.7%, p=0.012), but lesser area of lipid (42.1%±16.9%, p=0.034) when compared to non-radiation-induced CPs (3.0%±5.7% and 46.3%±17.9% respectively). Age, radiation and number of CVRF were significantly associated with the CA burden (p<0.001). Besides, age was significantly associated with the amount of lipid and calcification within CPs (p<0.001). Conclusions Compared to CVRF subjects, post-RT NPC patients were more susceptible to carotid plaque formation with less lipid content. Considering both CA burden and plaque component, both post-RT NPC patients and individuals with CVRF have a high risk of cerebrovascular diseases.