Investigation of Cardiac Cycle-dependent Hemodynamic Changes of Plaques in Symptomatic, Mild Carotid Artery Stenosis Using High-frame-rate Vector Flow

Background/Objective: To analyze the hemodynamic characteristics of symptomatic, mild carotid artery stenoses during different cardiac phases using high-frame-rate vector flow (HiFR-Vflow) imaging. Methods : Carotid atherosclerotic plaques were evaluated and classified into symptomatic and asymptomatic groups using HiFR-Vflow. Collected clinical data included age, sex, history of smoking, hypertension, diabetes, systolic blood pressure, diastolic blood pressure, and heart rate. Parameters including plaque echogenicity, morphology, length, thickness, cross-sectional area, area stenosis rate, and eccentricity index (EI) were obtained using B-mode ultrasound and color Doppler flow imaging. Hemodynamic characteristics including oscillatory shear index (OSI), T-Max, TAMean, TA Tur, MAX, turbulence (Tur), and maximum (Max) wall shear stress (WSS) within different cardiac cycle phases were also obtained. Results : The two groups did not differ significantly in terms of clinical data. The symptomatic group demonstrated significantly greater plaque thickness (P < 0.001), higher EI (P < 0.001), and larger cross-sectional area (P < 0.001) than in the asymptomatic group, and the plaque morphology was clearly different between the two groups (P < 0.001). The symptomatic group had significantly higher T-Max and TA Tur values in the region of interest. The OSI and Max WSS values were higher in the symptomatic group. Across different cardiac phases, MAX, Tur, and Max WSS initially increased and then decreased. Conclusions : The hemodynamic features of symptomatic, mild carotid stenoses are higher OSI and Tur values in the systolic phase. HiFR-Vflow enables real-time visualization and quantitative analysis of cardiac cycle-dependent hemodynamic changes, thereby assisting in the clinical risk stratification of carotid plaques.