ABSTRACT
Objective: To investigate the feasibility of energy spectrum CT angiography (CTA) in distinguishing the components of atherosclerosis plaque in carotid artery, and to analyze the relationship of different type atherosclerosis plaque with cerebral infarction. Methods: Energy spectrum CTA and head MRI were performed on 60 patients with carotid artery stenosis detected with ultrasound. CT value and effective atomic number of plaque, fat, muscle and bone tissue were measured, respectively. The characteristic energy spectrum curve of average CT value in 40-140 keV single energy image were obtained, and slope of energy spectrum curve was calculated. Cerebral infarction was evaluated based on MRI results. According to the results of energy spectrum CTA, the plaques were divided into lipid plaque, lipid core-dominated mixed plaque, fibrous composites-dominated mixed plaque, fibrous plaque and calcified plaque. The lipid plaque and lipid/fiber mixed plaque were classified as unstable plaque, and the fibrous plaque and calcified plaque were classified as stable plaque. The differences of the slope of energy spectrum curve and effective atomic number in patients of each type plaques were compared. The incidences of cerebral infarction in patients with various types of plaques were correlated. Results: A total of 109 carotid plaques were enrolled, including 21 lipid plaque, 11 lipid core-dominated mixed plaque, 30 fibrous composites-dominated mixed plaque, 15 fibrous plaque and 32 calcified plaque. Statistical differences of the corresponding energy curve slope and effective atomic number wer found among different type plaques (F=1 494. 83, 2 108. 74, both P<0.01). Totally 19, 11, 19, 10 and 20 patients were found with lipid plaque, lipid core-dominated mixed plaque, fibrous composites-dominated mixed plaque, fibrous plaque and calcified plaque, among them MRI detected cerebral infarction in 13, 6, 7, 2 and 1 patient, and the incidence of cerebral infarction was 68.42% (13/19), 54.55% (6/11), 36.84% (7/19), 11.11% (1/9), and 0 (0/20), respectively. The incidence of cerebral infarction in all 60 patients was 45.00%(27/60, in those with unstable plaque or stable plaque was 53.06% (26/49) and 3.33% (1/30), respectively. Conclusion: Energy spectrum CTA could be used for detailed analysis on the components and types of carotid plaques. The more the lipid components of plaque, the worse its stability, and the higher the risk of cerebral infarction.