Evaluation To Influence Of Characteristics Of Intracranial Atherosclerosis Plaque On Cerebral Blood Flow By Using 3D-ASL And HR-MRI

Objective: To characterize intracranial plaque and cerebral blood flow by using three-dimensional arterial spin labeling(3D-ASL)and high-resolution magnetic resonance imaging(HR-MRI)to investigate the relationship between intracranial atherosclerosis and cerebrovascular ischemic events,in a cohort of patients with middle cerebral artery(MCA)stenosis.Methods: The study was approved by the institutional review board of our hospital.Patients who underwent HR-MRI and 3D-ASL between May2019 and May 2020 in our hospital suggesting at least one plaque in unilateral stenotic middle cerebral artery were consecutively enrolled in the study.All patents were divided into symptomatic group and asymptomatic group based on the presence of cerebral ischemic event recently.Each identified plaque was classified as vulnerable or nonvulnerable based on HR-MR images by two experienced radiologists.Luminal stenosis was categorized on HR-MRI and MRA(mild,25-49%;moderate,50-69%;severe,70-99%).CBF and r CBF in separate region were calculated on 3D-ASL pseudo-color images by two technicians drawing manually interest of region(ROI)on cortical gray matter(anteroinferior frontal lobe,temporal lobe,posterosuperior frontal lobe,and parietal lobe).Inter-reader agreement for CBF measurements were performed by using the intraclass correlation coefficient(ICC).CBF of stenotic and normal sides of each ROI and r CBF at two post-labeling delays(PLD)were assessed by using paired-samples t test or Wilcoxon signed rank test.Clinical information,plaque characteristics,and cerebral perfusion parameters were compared between symptomatic and asymptomatic groups by using independent-samples t test or Wilcoxon rank sum test,Chi-square test or Fisher exact test.Multivariable linear regression was constructed to analysis the association of cerebral perfusion with plaque characteristics.Associations of the likelihood of ischemic symptoms with plaque characteristics were estimated with logistic regression.Results: Fifty-three plaques and 212 pairs of ROIs in 53 patients(51.81± 14.94 years;45 men)were used to analysis.Inter-reader agreement for CBF measurements were excellent(all ICC > 0.90).Mean CBF of the stenotic side in each ROI was significantly lower than of the normal side in patients with severe stenosis at PLD of 1.5s(P < 0.05),while the difference was not statistically significant at PLD of 2.5s(P > 0.05).Mean r CBF of two delays were both lower in the symptomatic group than in the asymptomatic group(P= 0.045,P = 0.004).Vulnerable plaques had a higher proportion in the symptomatic group than in the asymptomatic group(94% vs.64%,P = 0.011),while luminal stenosis showed no difference between the two groups.Multivariable linear regression analysis showed severe luminal stenosis was associated with the value of r CBF at PLD of 1.5s.(Coefficient =-0.012;P =0.017).Plaque vulnerability was associated with the value of r CBF at PLD of2.5s(Coefficient =-0.137;P = 0.032).Logistic regression analysis showed plaque vulnerability was associated with appearance of ischemic symptoms(odds ratio = 8.286;95% confidence interval: 1.551,44.264,P = 0.013).Conclusions:1.Severe luminal stenosis of intracranial artery is a leading cause of decreased antegrade perfusion in the target territory.2.Cerebral ischemic symptoms in patients with severe intracranial luminal stenosis is associated with deficit of collateral perfusion in the target territory.3.Plaque vulnerability,associated with decreased collateral flow,is an independent risk factor for ischemic symptoms.