Abstract Body: Introduction: The middle cerebral artery (MCA) is the most common site for inrtacranial atherosclerotic stenosis. Evidence has shown that carotid artery geometries are independently associated with ipsilateral MCA atherosclerosis. However, whether the role of the blood flow dynamics underlies this association remains uncertain. We aimed to investigate associations between the hemodynamics of internal carotid artery (ICA) and ipsilateral MCA atherosclerosis.
Methods: Patients diagnosed with unilateral MCA atherosclerosis by computed tomography angiography were enrolled from July 2021 to June 2024. Demographic data, risk factors and the history of ischemic stroke of all patients were recorded. 4D Flow MR scan from both common carotid artery to the circle of Willis was performed on a 3.0T MR system equipped with a 16-channel head-neck coil for all patients. Hemodynamic parameters including lumen area, velocity, flow and wall shear stress (WSS) at the midpoint of ipsilateral C1 segment (C1_ips) and contralateral C1 segment (C1_con) were measured with GTFLOW. The hemodynamic characteristics in the C1_ips and the C1_con of all patients were investigated, the hemodynamic features at bilateral C1 between the MCA mild-moderate stenosis group and the MCA severe stenosis/occlusion group were compared. Associations between hemodynamics of C1 and MCA atherosclerosis were analyzed.
Results: Among 105 patients (77 men, mean age 63 years old) with unilateral MCA atherosclerosis, 50 patients presented with mild/moderate stenosis and 55 patients with severe stenosis or occlusion. Compared with the C1_con, the C1_ips showed decreased lumen area, velocity, flow and WSS in all patients. Patients with MCA severe stenosis/occlusion showed reduced lumen area, flow in the C1_ips, along with higher PSV at the C1_con than patients with MCA mild-moderate stenosis. After adjusting for age, gender, BMI and traditional risk factors, low flow (both the flow_avg and flow_max were less than the mean value of all patients' C1_ips) was independently associated with ipsilateral MCA severe stenosis or occlusion (OR,7.65[95%CI (2.74-21.35), p<0.001).
Conclusions: Both the lumen area and hemodynamics at the ipsilateral C1 were lower than those at the contralateral C1 in patients with unilateral MCA atherosclerosis. Low flow of the ipsilateral C1 was independently associated with MCA severe stenosis or occlusion, providing new insights into the pathophysiology of unilateral MCA progressive atherosclerosis.