Evaluation of Carotid Atherosclerosis Using Three-Phase CT

Abstract

Purpose : Carotid atherosclerotic plaque (CAP) was evaluated by three-phase CT (TPCT; CTpre, CTartery, CTdelay). The purposes ofthis study are to: (1) to determine optimal phase for the visualization of CAP components; (2) evaluate whether there is asignificant difference in the quantitative CT Hounsfield unit (CTHUs) of the CAP components between the arterial and delayphase.Materials and Methods : Two reviewers evaluated the detection rate and image quality for CAP components on CTartery andCTdelay source images in 36 patients. Quantitative analysis of the CTHUs for the soft plaque and outer wall was performed in 47arteries. The CTHUs were measured for the soft plaque and the outer wall using the manual ROI method for each carotidplaque. The difference of image quality on CTartery and CTdelay, the difference of the CTHUs according to CT phase, the differencein CTHUs according to the arterial symptomatology or stenosis degree were statistically evaluated.Results : CTdelay was the optimal phase for the delineation of soft plaque and outer wall enhancement. The CAP componentsshowed progressive delayed enhancement. There were statistically significant increase in the enhancement of the outer wallthrough TPCT (p <0.001). CTHUs of soft plaque and outer wall on CTdelay and CTartery did not show significant correlations withsymptomatology. The CTHUs of soft plaque on CTartery (p =0.02) and CTHUs of the outer wall on CTdelay (p =0.01) weresignificantly higher in the group of symptomatic arteries or severely stenotic arteries together that that in the group ofasymptomatic arteries with less than 70% stenosis.Conclusion : CTdelay was the optimal phase for plaque detection and the characterization of plaque components.