Improved PWI Methodology in Acute Clinical Stroke

描述(由申请人提供)： 这份新报告的总体目标是暂时区分亚临床少血症高于临床损害阈值(CBF降低但高于临界弥散ADC阈值)和低于生存阈值和出血风险的大脑。在这项为期4年的研究中，每年将研究24名在症状出现后6-24小时内出现中风样症状的住院患者。这些患者将显示广泛的血流值和生理状态，以确定分段ADC测量的血流灌注的时间相关性，但足够稳定，可以接受验证假设所需的CT和MR研究。 这项研究的一个重要方面是建立MR团注追踪作为一种定量灌注法。我们将提高磁共振灌注成像(PWI)定量绘制血流灌注图的能力(特定目标1)，以便在进展性急性临床卒中(特定目标2)的背景下建立时间扩散阈值和血流阈值。为此，我们将从双回波/双激发梯度回波GRE-EPI团注跟踪动脉输入AIF派生的PWI图像中获得定量脑血流(CBF)图。我们将测试这样一种假设：与用户定义的AIF选择相比，从我们的自动AIF选择去卷积例程中测量的CBF值将更好地与XeCT值(从相同的患者在确诊时获得)更好地关联。然后，我们将把MR灌注(CBF、MTT值和CBV)和XeCT CBF值共同记录到这些患者的灰质和白质弥散(轨迹ADC、11-13个特征值和分数各向异性FA)分布上。 在这些研究成功完成后，我们将建立一些高度准确的预测工具，通过提供演变中的脑梗塞的局部生理状态的快照，使用MRI来评估脑缺血。我们相信，这些信息将导致临床管理的新措施，并最终将允许在单个患者的治疗时间窗口内做出管理决定，而不是目前僵化的时间窗口的概念。

DESCRIPTION (provided by applicant): The overall goal of this new submission is to temporally differentiate subclinical oligemia above the threshold for clinical impairment (reduced CBF yet above a critical diffusion ADC threshold) from brain below thresholds of viability and at risk for hemorrhage. For each year of this 4-year study, 24 consecutive inpatients presenting with stroke-like symptoms between 6-24 hours of symptom onset will be studied. These patients will display a wide range of blood flow values and physiological states over which to determine the temporal dependences of perfusion on segmented ADC measures, yet be stable enough to undergo both the CT and MR studies needed to test the hypotheses. One important aspect of this study is to establish MR bolus-tracking as a quantitative perfusion method. We will improve the ability of perfusion-weighted MRI (PWI) to quantitatively map perfusion (Specific Aim 1) in order to establish temporal diffusion and flow thresholds in the setting of evolving acute clinical stroke (Specific Aim 2). To do this, we will acquire quantitative cerebral blood flow (CBF) maps derived from dualecho/ dual-shot gradient-echo GRE-EPI bolus tracking arterial input AIF-derived PWI images. We will test the hypothesis that CBF values measured from our automated AIF selection deconvolution routines will better correlate with the "gold standard" XeCT values (acquired from the same patients at presentation) than will user-defined AIF selections. We will then co-register the MR perfusion (CBF, MTT, and CBV) and XeCT CBF values onto segmented gray and white matter diffusion (traceADC, 11-13 eigenvalues, and fractional anisotropy FA) distributions in these patients. Upon successful completion of these studies, we will have established a number of highly accurate predictive tools for evaluating brain ischemia using MRI by providing a snap-shot of the regional physiological status of evolving infarcts. We believe that this information will lead to new measures for clinical management and will eventually allow management decisions to be made within an individual patient's therapeutic time window as opposed to current conceptions of a rigid time window.