Dual Energy Computed Tomography for Determining Coronary Lesion-Specific Ischemia

描述(申请人提供)：本申请的总体目标是开发一种新的基于定量计算机断层扫描(CT)的方法，用于精确识别导致缺血的冠状动脉病变。目前，还没有一种非侵入性测试来确定冠状动脉(CAD)狭窄的严重程度，以及狭窄是否会导致缺血或心肌灌注减少。心肌灌注成像(MPI)生理性负荷试验是评价冠心病的传统方法，它能识别缺血，但不能识别狭窄。相比之下，冠状动脉CT血管成像(CCTA)可以直接对CAD进行解剖可视化，但不能区分狭窄是否导致缺血。通过有创方法，分别通过有创冠状动脉造影术和血流储备分数(FFR)对CAD进行解剖-生理学联合评估，可以提高对导致缺血的狭窄患者的诊断，减少不必要的血运重建，并改善临床结果。最近，通过在CCTA基础上增加CT灌注(CTP)，一种非侵入性的解剖-生理学联合方法成为可能。与MPI类似，CTP可以通过测量局部心肌信号衰减来对狭窄进行生理学评估。早期的CTP研究受到一些限制，包括：1)阴影伪影；2)运动伪影；3)缺乏定量方法来评估血流灌注；4)过度辐射；以及5)无法准确定位导致缺血的特定病变。投影 基于双能量CT(DECT)是一种新的CT技术，它直接解决了许多这些局限性，提供了显著减少伪影和定量测量心肌灌注的潜力。再加上减少运动伪影的时间分辨率的提高，DECT具有提高CTP诊断准确性的潜力，无疑将对目前对疑似CAD患者的诊断方法产生积极和重大的影响。这项建议的总体假设是，一种新的基于定量投影的DECT方法将能够区分患有心肌缺血的个体，以及识别导致心肌缺血的特定冠状动脉病变。在这项研究中，有三个具体目标：1)开发一种准确量化材料密度的新的DECT方法；2)确定新的DECT方法在体外诊断心肌灌注的准确性；3)评估新的DECT方法在体内诊断CTP以确定冠状动脉病变特异性缺血的准确性，并与侵入性FFR“金”标准进行比较。

DESCRIPTION (provided by applicant): The OVERALL OBJECTIVE of this application is to develop a novel quantitative computed tomography (CT)-based method for precise identification of coronary artery lesions that cause ischemia. At present, no non-invasive test exists that determines both coronary artery disease (CAD) stenosis severity and whether a stenosis causes ischemia, or reduced myocardial perfusion. Physiologic stress testing by myocardial perfusion imaging (MPI) is the traditional method for evaluating CAD, and identifies ischemia but not stenoses. In contrast, coronary CT angiography (CCTA) enables direct anatomic visualization of CAD, but cannot discriminate whether a stenosis causes ischemia. By invasive methods, a combined anatomic-physiologic approach to CAD evaluation by invasive coronary angiography and fractional flow reserve (FFR), respectively, improves diagnosis of patients with stenoses that cause ischemia, reduces unnecessary revascularization, and improves clinical outcomes. Recently, a combined anatomic-physiologic approach by non-invasive methods has become possible by the addition of CT perfusion (CTP) to CCTA. Similar to MPI, CTP permits physiologic assessment of stenoses through measures of regional myocardial signal attenuation. Early studies of CTP have been constrained by several limitations, including: 1) shading artifacts; 2) motion artifacts; 3) lack of a quantitative method for assessing perfusion; 4 excess radiation; and 5) an inability to pinpoint specific lesions that cause ischemia. Projection based dual-energy CT (DECT) is a novel CT technology that directly addresses many of these limitations, providing the potential for dramatic reduction in artifacts and quantitative measurement of myocardial perfusion. Coupled with improvements in temporal resolution that reduce motion artifacts, DECT holds the potential to improve the diagnostic accuracy of CTP, with an undoubtedly positive and significant impact on the current diagnostic approach to patients with suspected CAD. The OVERALL HYPOTHESIS of this proposal is that a novel quantitative projection-based DECT-based method will enable discrimination of individuals who suffer from myocardial ischemia as well as the identification of the specific coronary artery lesions that are the cause. For this study, there are 3 specific aims: 1) Develop a novel DECT method that accurately quantifies material density; 2) Determine the in vitro diagnostic accuracy of novel DECT method to characterize myocardial perfusion; 3) Evaluate the in vivo diagnostic accuracy of CTP by the novel DECT method to determine coronary lesion-specific ischemia, as compared to an invasive FFR "gold" standard.