Imaging Collaterals in Acute Stroke (iCAS)

描述（由申请人提供）：侧支血流在急性缺血性卒中中起着核心作用，良好的侧支血流的存在与改善临床和影像学结果有关，无论是否成功再通。尽管如此，目前唯一评估侧支是否充足的方法是全面且昂贵的数字减影脑血管造影（DSA）。如果能够使用基于断层成像的非侵入性成像方法对侧枝进行可视化，将是非常有益的，这样早期的治疗决策就可以纳入这一关键信息。目的和方法对急性卒中侧支（iCAS）研究的总体目标是使用动脉自旋标记（ASL）（一种非对比MRI技术）识别和量化通过侧支途径输送的脑血流量（CBF），并确定其对缺血性病变生长和患者预后的影响。我们将对180名急性脑卒中患者进行前瞻性、多中心研究，这些患者在4.5-12小时的时间窗内成像，伴有大血管闭塞性脑卒中，正在考虑进行血管内溶栓治疗。我们将在我们的快速卒中方案中增加两个ASL序列：用于识别侧枝的伪连续ASL （pcASL， 2.5分钟）和用于测量与动脉到达延迟无关的定量CBF的速度选择性ASL （VS-ASL， 2.5分钟）。在Aim 1中，我们将证明DSA和pcASL在抵押品评估中的等效性，并使用VS-ASL确定抵押品与定量CBF之间的关系。然后，在Aim 2中，我们将确定ASL是否可以用于补充或替代传统的静脉注射造影剂PWI，确定侧枝评估对缺血性病变生长的预测能力，并通过检查侧枝、血运重建和患者预后之间的关系，评估如何将侧枝测量纳入血管内治疗的患者选择算法。我们相信这些目标的成功实现将通过验证一种基于非侵入性mri的方法来评估抵押品的存在和它们提供的CBF量，从而显着改善急性卒中的护理。iCAS将是首个前瞻性、多中心的ASL研究，ASL是一种很有前途的新型非对比灌注方法。特别是，使用VS-ASL在急性卒中的连续时间点获得定量的CBF测量将获得关于这一关键血流动力学参数的宝贵信息。它将提供一个框架，将抵押品的地位纳入治疗决策，特别是通过回答是否有非常好或非常差的抵押品的患者受益于再通的问题。本研究将有助于更好地了解ASL测量在严重脑血管疾病患者中的益处，并增强MRI在急性缺血性脑卒中中的诊断能力。

DESCRIPTION (provided by applicant): Collateral blood flow plays a central role during acute ischemic stroke, and the presence of good collaterals has been linked to improved clinical and radiologi- cal outcome measures both with and without successful recanalization. Despite this, the only method to assess adequacy of collaterals currently is in- vasive and expensive, digital subtraction cerebral angiography (DSA). It would be tremendously beneficial if collaterals could be visualized using a tomo- graphic, non-invasive imaging based modality, so that early treatment deci- sions could incorporate this critical information. AIMS AND METHODS The overall goal of the imaging the Collaterals in Acute Stroke (iCAS) study, is to identify and quantify cerebral blood flow (CBF) delivered via collateral routes using arterial spin labeling (ASL), a non-contrast MRI technique, and to determine its impact on ischemic lesion growth and patient outcome. We will perform a prospective, multi-center study of 180 acute stroke patients imaged in the 4.5-12 hr time window with large vessel occlusive stroke who are under consideration for endovascular thrombolytic therapy. We will add two ASL sequences to our rapid stroke protocol: pseudocontinuous ASL (pcASL, 2.5 min) for identifying collaterals and velocity-selective ASL (VS-ASL, 2.5 min) for measuring quantitative CBF independent of arterial arrival delay. In Aim 1, we will demonstrate equivalence between DSA and pcASL for collateral assessment, and determine the relationship between collateral and quantitative CBF using VS-ASL. Then, in Aim 2, we will determine whether ASL might be used to supplement or replace conventional bolus contrast PWI, determine the predictive ability of collateral assessment upon ischemic lesion growth, and evaluate how to incorporate collateral measurements into patient selection algorithms for endovascular therapy by examining the relationship between collaterals, revascularization, and patient outcome. SIGNIFICANCE We believe successful attainment of these aims will markedly improve acute stroke care by validating a non-invasive MRI-based method to assess both the presence of collaterals and the amount of CBF they deliver. iCAS will be the first prospective, multi-center study of ASL, a promising new non-contrast perfusion method, in acute stroke. In particular, the use of VS-ASL to obtain quantitative CBF measurements at serial timepoints in acute stroke will yield invaluable information on this critica hemodynamic parameter. It will provide a framework for incorporating collateral status into treatment decision-making, specifically by answering the question of whether patients with either very good or very poor collaterals benefit from recanalization. This study will lead to bettr understanding of the benefit of ASL measurements in patients with severe cerebrovascular disease and enhance the already significant diagnostic power of MRI in acute ischemic stroke.