Fibrous cap state in carotid atherosclerotic plaque: Ultrasound diagnostic capabilities and implication for ischemic stroke risk stratification

Objective. To systematize the ultrasound features of various fibrous cap (FC) states of carotid atherosclerotic plaques that determine the risk of ischemic stroke, based on an analysis of the morphological changes in its surface that occur during plaque destabilization. Content. This manuscript summarizes data both from literature and the authors' own experience. The FC separates the lipid-necrotic plaque core from the vessel lumen and is the most vulnerable to damage structure. Its thinning, rupture, and ulceration reflect different states of plaque destabilization and underlie the new Carotid Plaque-RADS stroke risk classification. The morphological features of each state are described, the threshold values for FC thickness are discussed. Ultrasound criteria for thick and thin plaque caps, plaque rupture, and healed ulceration are presented. Conclusion. In routine practice, FC thickness on ultrasound is assessed qualitatively using the “seen/not seen” basis without quantitative measurement. Ultrasound detects cap ruptures with high accuracy and ulcerations with moderate accuracy. Contrast enhancement, three-dimensional reconstruction, and low-velocity blood flow mapping could improve diagnostic accuracy. Assessing the plaque’s FC status together with plaque structure and degree of stenosis is advisable for improving risk stratification and personalizing patient treatment.