Assessment of carotid artery stenosis and hemodynamic risk factors related to stroke based on 4D Flow MRI
Objective:In this study,4D flow magnetic resonance imaging(4D Flow MRI)was employed to analyze the hemodynamics of moderate and severe atherosclerotic stenosis in unilateral carotid arteries and investigate the hemodynamic risk factors influencing carotid atherosclerotic stenosis and acute ischemic stroke.Materials and Methods:A total of 20 patients diagnosed with moderate to severe unilateral carotid atherosclerosis using ultrasonography were recruited from January to December at the First Hospital of Jilin University,along with age-and vascular condition-matched normal volunteers(n=26).Clinical data and magnetic resonance data were collected.Hemodynamic parameters such as blood flow,blood flow velocity,wall shear stress(WSS),maximum pressure gradient and energy loss were obtained by CVI 42 software.Compare the measured values between groups for statistical differences using t-tests or Mann Whitney U-tests and subgroup analysis was performed on acute cerebral infarction and non-acute cerebral infarction to explore the effect of hemodynamic changes at the stenosis on the occurrence of stroke.Results:The mean blood flow,maximum blood flow,total volume and mean relative pressure difference in the study group were significantly lower than those in the control group(P<0.05),while the maximum energy loss and average energy loss were higher than those in the control group(P<0.05).The mean blood flow was negatively correlated with the degree of stenosis(r=-0.420,P<0.05).There were significant differences in mean blood flow,mean velocity,minimum velocity,maximum blood flow,total volume,and verage axial wall shear stress in the upper,central and lower reaches of all stenosis vessels(P<0.05),and the maximum pressure gradient of downstream acute cerebral infarction group was lower than that of non-acute cerebral infarction group(P<0.05).Conclusions:Visualization and quantitative analysis of 4D Flow MRI shows that energy loss in addition to blood flow was helpful for realistic carotid artery stenosis.Low WSS and downstream maximum pressure gradient of carotid artery stenosis may serve as potential biomarkers for stroke prediction.