Intracranial atherosclerotic disease (ICAD) is a common cause of ischaemic stroke and transient ischaemic attack (TIA) with a high recurrence rate. It is often referred to as intracranial atherosclerotic stenosis (ICAS), when the plaque has caused significant narrowing of the vessel lumen. The lesion is usually considered ‘symptomatic ICAD/ICAS’ (sICAD/sICAS) when it has caused an ischaemic stroke or TIA. The severity of luminal stenosis has long been established as a prognostic factor for stroke relapse in sICAS. Yet, accumulating studies have also reported the important roles of plaque vulnerability, cerebral haemodynamics, collateral circulation, cerebral autoregulation and other factors in altering the stroke risks across patients with sICAS. In this review article, we focus on cerebral haemodynamics in sICAS. We reviewed imaging modalities/methods in assessing cerebral haemodynamics, the haemodynamic metrics provided by these methods and application of these methods in research and clinical practice. More importantly, we reviewed the significance of these haemodynamic features in governing the risk of stroke recurrence in sICAS. We also discussed other clinical implications of these haemodynamic features in sICAS, such as the associations with collateral recruitment and evolution of the lesion under medical treatment, and indications for more individualised blood pressure management for secondary stroke prevention. We then put forward some knowledge gaps and future directions on these topics.

中文翻译：

---

有症状颅内动脉粥样硬化性疾病的脑血流动力学：评估方法和临床意义的叙述性回顾

颅内动脉粥样硬化性疾病（ICAD）是缺血性脑卒中和短暂性脑缺血发作（TIA）的常见原因，且复发率高。当斑块导致血管腔显着狭窄时，它通常被称为颅内动​​脉粥样硬化性狭窄（ICAS）。当病变引起缺血性中风或 TIA 时，通常被认为是“症状性 ICAD/ICAS”(sICAD/sICAS)。管腔狭窄的严重程度早已被确定为 sICAS 中风复发的预后因素。然而，越来越多的研究也报道了斑块脆弱性、脑血流动力学、侧支循环、脑自动调节和其他因素在改变 sICAS 患者中风风险方面的重要作用。在这篇综述文章中，我们重点关注 sICAS 中的脑血流动力学。我们回顾了评估脑血流动力学的成像模式/方法、这些方法提供的血流动力学指标以及这些方法在研究和临床实践中的应用。更重要的是，我们回顾了这些血流动力学特征在控制 sICAS 卒中复发风险中的重要性。我们还讨论了 sICAS 中这些血流动力学特征的其他临床意义，例如与侧枝募集和医学治疗下病变演变的关联，以及用于二级中风预防的更个体化的血压管理的适应症。然后我们提出了这些主题的一些知识差距和未来方向。