Application Of 4D MRI In Hemodynamics Of Carotid Atherosclerosis

Atherosclerosis carotid artery stenosis is common in Asian population.Previous studies believed that vascular stenosis greater than 70% is independently related to cerebrovascular events,which is considered as a high-risk feature.However,more and more studies believe that hemodynamic factors are closely related to the occurrence and development of carotid artery atherosclerosis.Most of the previous studies focused on in vitro,animal models,in vivo 2D-PC and healthy volunteers,while there were few studies on hemodynamics in patients with in vivo carotid artery stenosis.Objective:4D MRI imaging(4D-flow)was used to study the hemodynamics of severe atherosclerotic stenosis vessels in unilateral carotid artery,and to explore the hemodynamic related risk factors affecting internal carotid artery atherosclerotic stenosis and acute ischemic stroke.Methods:Clinical data of patients with moderate to severe unilateral carotid atherosclerosis diagnosed by ultrasound(n=20)admitted to the First Hospital of Jilin University from January 2022 to December 2022 and normal volunteers matched in age and vascular conditions during the same period(n=26)were collected.TOF-MRA,4D-Flow,routine T1 WI,T2WI,FLAIR and DWI were performed in the study group and the healthy control group,respectively.Each original Flow image data in the study group and the control group were imported into CVI42.0 software for processing.Hemodynamic parameters such as blood flow,blood velocity,wall WSS,maximum pressure gradient,and energy loss were obtained to analyze hemodynamic changes at the stenosis site,evaluate the difference of hemodynamic parameters between the study group and the control group,and perform subgroup analysis for acute cerebral infarction and non-acute cerebral infarction,and investigate the effect of hemodynamic changes in stenosis on stroke occurrence.Results:The average blood flow,maximum blood flow,total volume and average relative pressure difference of the study group were significantly lower than those of the control group(P < 0.05),but the maximum energy loss and average energy loss were higher than those of the control group(P < 0.05).Mean blood flow in severe stenosis was lower than that in moderate stenosis.The hemodynamic comparison results of upstream,center and downstream stenosis of all stenosis vessels showed that there were significant differences in average blood flow,average velocity,minimum velocity,maximum blood flow,total volume and average axial WSS(P < 0.05).The maximum pressure gradient of downstream acute cerebral infarction group was lower than that of non-acute cerebral infarction group(P < 0.05).Conclusion:1.4D blood flow MRI can realize the visualization and quantification of carotid atherosclerosis blood flow,which may have positive significance for the diagnosis and treatment of pericarotid atherosclerosis.2.Blood flow decreased after carotid artery stenosis,and decreased with the increase of stenosis degree;The energy loss at both ends of the stenosis is larger,which is helpful for showing carotid stenosis.3.Low WSS has a certain effect on the occurrence of stroke,and the maximum pressure gradient downstream of carotid artery stenosis may be used as a potential biomarker to predict stroke.