Supplementary Material for: Angiographic Systems for Classifying Distal Arterial Occlusions

Background: Extensive randomized controlled clinical trials for endovascular thrombectomy in anterior circulation large vessel occlusions (internal carotid arteries and M1 segment of middle cerebral arteries) have been published over the past decade, but there have not been randomized controlled trials for distal arterial occlusions to date. Distal arterial occlusion randomized controlled trials are essential to decide on patient selection, imaging criteria, and endovascular approach to improve the outcome and reduce complications. Summary: The definition of distal arterial occlusion is however unclear, and we believe that a uniform nomenclature of distal arterial occlusions is essential for the design of robust randomized controlled studies. We undertook a systematic literature review and comprehensive analysis of 70 articles looking at distal arterial occlusions and previous attempts at classifying them as well as comparing their similarities and differences with a more selective look at the middle cerebral artery. Thirty-two articles were finally deemed suitable and included for this review. In this review article, we present 3 disparate classifications of distal arterial occlusions, namely, classical/anatomical, functional/imaging, and structural/calibre, and compare the similarities and differences between them. Key Messages: We propose the adoption of functional/imaging classification to guide the identification of distal arterial occlusions with the M2 segment starting at the point of bifurcation of the middle cerebral artery trunk/M1 segment. With regards to the anterior temporal artery, we propose that it will be considered a branch of the M1 and only be considered as the M2 segment if it is a holo-temporal artery. We believe that this is a practical method of classification in the time-critical decision-making period.背景：过去十年间，针对前循环大血管闭塞（anterior circulation large vessel occlusions）的颈内动脉（internal carotid arteries）及大脑中动脉（middle cerebral arteries）M1段（M1 segment）的血管内取栓术（endovascular thrombectomy）已发表大量随机对照临床试验（randomized controlled clinical trials），但迄今尚未开展针对远端动脉闭塞（distal arterial occlusions）的随机对照试验。远端动脉闭塞的随机对照试验对于明确患者筛选标准、影像评估指标及血管内治疗方案，以改善临床预后、减少并发症至关重要。 综述概要：然而目前远端动脉闭塞的定义尚不明确，我们认为统一远端动脉闭塞的命名规范（nomenclature）对于设计严谨的随机对照研究必不可少。本团队开展了系统文献回顾（systematic literature review）与综合分析，共检索分析70篇涉及远端动脉闭塞及其既往分类尝试的文献，对比了各类分类方式的异同，并重点聚焦大脑中动脉相关内容。最终筛选纳入32篇符合标准的文献进行本次综述。在本文中，我们梳理了远端动脉闭塞的三类截然不同的分类体系，即经典/解剖学分类、功能/影像学分类以及结构/管径（calibre）分类，并对比了各类分类间的异同。 核心要点：我们建议采用功能/影像学分类体系指导远端动脉闭塞的识别，其中大脑中动脉M2段（M2 segment）起始于大脑中动脉干/M1段的分叉点。针对颞前动脉，我们提出其应被归为M1段的分支，仅当它为全颞动脉（holo-temporal artery）时方可归类为M2段。我们认为该分类方法在时间紧迫的临床决策场景中具备实践可行性。