Characterizing Hemodynamic Compensation and Stroke Risk in Stenosis Patients

描述(由申请人提供)：这项工作的总体目标是评估中风风险和血流动力学补偿策略之间的关系，通过使用新的3.0特斯拉MRI方案，在有症状的颅内(IC)狭窄闭塞疾病患者中进行测量。最近的研究表明，有症状的颈内动脉狭窄患者的两年内缺血性卒中发生率很高。IC狭窄患者的治疗包括血管成形术、IC支架植入或搭桥术，然而，识别最有可能从这些更积极的干预中受益的患者，而不仅仅是医疗管理，一直是个问题。为了更好地确定卒中风险和指导治疗决策，可能需要准确测量血液动力学损害。具体地说，在IC狭窄伴脑灌流压(CPP)受损的患者中，血流动力学受损的程度反映了血管系统增加动脉脑血容量(ACBV)和/或发展侧支以补充脑血流量(CBF)的自我调节能力。CBF侧化和CBV自动调节的流行被认为与卒中风险唯一相关；然而，这种相关性的程度一直存在争议。对卒中风险进行分层的关键障碍在于缺乏1)以高特异性测量多个血流动力学因素的方法和(2)能够监测损害纵向进展的非侵入性方法。我们已经证明了相对较新的非侵入性MRI方法在评估脑血管反应性(CVR)、aCBV和侧支CBF方面的临床实用性。我们假设，通过对这些参数的集体测量，可以更完整地揭示中风风险。因此，我们建议实施一种新的、有效的血流动力学MRI方案来评估颈内动脉狭窄患者的组织水平损害和补偿策略。通过综合测量多个脑区的侧支CBF、aCBV和CVR，结合包含上述变量作为可能的预后因素的统计模型，我们将量化两年中风风险与血流动力学补偿机制的关联程度。这项研究的无创性和多方面的范围旨在扩大卒中的诊断基础设施，并阐明在这一高危人群中卒中的新的血流动力学预后指标。

DESCRIPTION (provided by applicant): The overall aim of this work is to assess the relationship between stroke risk and hemodynamic compensation strategies, as measured using a novel 3.0 Tesla MRI protocol, in patients with symptomatic intracranial (IC) steno-occlusive disease. Recent studies have shown high two-year ischemic stroke rates in symptomatic patients with IC arterial stenosis. Therapy for IC stenosis patients includes revascularization with angioplasty, IC stenting, or bypass, however identification of patients most likely to benefit from these more aggressive interventions, rather than medical management alone, has been problematic. Accurate measurements of hemodynamic compromise are likely required to better define stroke risk and guide treatment decisions. Specifically, in IC stenosis patients with compromised cerebral perfusion pressure (CPP), the extent of hemodynamic compromise reflects the autoregulatory capacity of vasculature to increase arterial cerebral blood volume (aCBV) and/or develop collaterals to supplement cerebral blood flow (CBF). The prevalence of CBF collateralization and aCBV autoregulation has been hypothesized to correlate uniquely with stroke risk; however the extent of this correlation has been debated. The critical barrier to stratifying stroke risk rests with a lack of i) methodology for measuring multiple hemodynamic factors with high specificity and (ii) noninvasive approaches capable of monitoring longitudinal progression of impairment. We have demonstrated the clinical utility of relatively new, noninvasive MRI approaches for assessing cerebrovascular reactivity (CVR), aCBV, and collateral CBF. We hypothesize that stroke risk can be more completely evinced from collective measurements of these parameters. Therefore, we propose to implement a novel, validated hemodynamic MRI protocol to assess tissue-level impairment and compensation strategies in patients with IC stenosis. Using a collective approach combining measurements of collateral CBF, aCBV and CVR in multiple brain regions, in conjunction with a statistical model incorporating the above variables as possible prognostic factors, we will quantify the extent to which two-year stroke risk is associated with hemodynamic compensation mechanisms. The noninvasive and multi-faceted scope of this investigation is intended to expand the diagnostic stroke infrastructure and elucidate new hemodynamic prognostic indicators of stroke in this high-risk population.