Variations of arterial compliance and vascular resistance due to plaque or infarct in a single vascular territory of the middle cerebral artery

Background: Arterial compliance (AC) and vascular resistance (VR) are crucial for the regulation capacity of the vascular system. However, alterations of these features and hemodynamics due to atherosclerosis in a single intracranial artery territory have not been extensively investigated. Thus this study aimed to examine the AC, VR, and hemodynamic variations due to plaque and infarction in the middle cerebral artery (MCA).Methods: Patients with symptomatic MCA atherosclerosis were recruited. Both sides of the MCA were assessed and then classified according to the following scheme: group 0, without plaque; group 1, with plaque but without infarct; group 2, with plaque and infarct in the supplying territories. Data on AC, VR, blood flow, and pulsatility index (PI) were obtained based on 4D flow magnetic resonance imaging (MRI) and the Windkessel model.Results: A total of 63 patients were recruited. After 17 MCAs were excluded (occlusion, n=6; poor image quality, n=11), datasets on 109 MCAs were finally collected and classified into group 0 (n=39), group 1 (n=40), and group 2 (n=30). From groups 0 to 2, there was a decrease in AC (0.0060 +/- 0.0031 vs. 0.0052 +/- 0.0029 vs. 0.0026 +/- 0.0020 mL/mmHg) and an increase in VR [28.65 +/- 16.11 vs. 42.59 +/- 27.53 vs. 63.21 +/- 40.37 mmHg/(mL/s)]. Compared to group 1, group 2 had significantly decreased AC (0.0052 +/- 0.0029 vs. 0.0026 +/- 0.0020 mL/mmHg; P=0.003) and increased VR [42.59 +/- 27.53 vs. 63.21 +/- 40.37 mmHg/(mL/s); P=0.021]. From group 0 to group 2, there was a decrease in blood flow (179.29 +/- 73.57 vs. 125.11 +/- 59.04 vs. 92.05 +/- 48.79 mL/min; P<0.001). The PI varied significantly among the 3 groups (0.86 +/- 0.20 vs. 1.12 +/- 0.50 vs. 0.79 +/- 0.16; P<0.001), with group 1 having the highest PI.Conclusions: With the occurrence of plaque and infarct, AC and blood flow progressively decrease while VR increases. The PI was the highest in the group with plaque and without infarct. Assessments of vascular function and hemodynamics in a single artery territory can clarify comprehensive alterations in the cerebral vascular system (CVS).