title: Intracranial atherosclerosis: From anatomy to pathophysiology.
abstract: Background Intracranial atherosclerotic stenosis is an important etiology subtype of ischemic stroke. Stenosis severity was thought to be the main reference index for clinical treatment and research. However, stenosis could not reflect the ischemia risk completely, instead the hemodynamic state across the lesion, the extent of collateral circulation, and perfusion impairment downstream the stenosis are more important. Aims We write this review aimed to summarize novel angiographic methods applied in the evaluation of functional severity of ICAS, and commented on their limitations and prospects in future research. Summary of review The main methods to estimate cerebral blood flow including fractional flow assessed by signal intensity ratio, computational fluid dynamics analysis or pressure wire, quantitative magnetic resonance angiography. Fractional flow as a series cerebral hemodynamic parameters may reflect the status of collateral circulation and cerebral blood flow. But the accuracy of the methods was not validated. The method to calculate fractional flow reserve in cardiovascular disease cannot duplicate in cerebrovascular disease. Fractional flow measurement by floating a pressure guidewire across the intracranial stenosis was technically feasible and safe. In the future researches, a non-invasive method should be established to identify high-risk intracranial lesions and may help in decision-making. Conclusions The relationship between stenosis and cerebral blood flow was individualized. Cerebral hemodynamic criteria should be used to screen patients to endovascular treatment, which will optimize the diagnosis and treatment strategies for patients with symptomatic intracranial artery stenosis.
authors.affiliation: 1 Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China.
authors.forename: Yuehua
authors.initials: Y
authors.lastname: Pu
authors.affiliation: 2 Department of Medicine and Therapeutics, the Chinese University of Hong Kong, Hong Kong SAR, China.
authors.forename: Linfang
authors.initials: L
authors.lastname: Lan
authors.affiliation: 2 Department of Medicine and Therapeutics, the Chinese University of Hong Kong, Hong Kong SAR, China.
authors.forename: Xinyi
authors.initials: X
authors.lastname: Leng
authors.affiliation: 2 Department of Medicine and Therapeutics, the Chinese University of Hong Kong, Hong Kong SAR, China.
authors.forename: Lawrence Ks
authors.initials: LK
authors.lastname: Wong
authors.affiliation: 1 Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, China.
authors.forename: Liping
authors.initials: L
authors.lastname: Liu
mesh_terms: D001921:Brain / Q000098:blood supply / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D006439:Hemodynamics; D006801:Humans; D002537:Intracranial Arteriosclerosis / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology*
keywords: Intracranial atherosclerosis; fractional flow; hemodynamics; ischemic stroke