Dual Energy Computed Tomography for Determining Coronary Lesion-Specific Ischemia

描述（由申请人提供）：本申请的总体目的是开发一种基于定量计算机断层扫描（CT）的新方法，用于精确识别导致缺血的冠状动脉病变。目前，没有非侵入性的测试存在，以确定冠状动脉疾病（CAD）狭窄的严重程度和狭窄是否会导致缺血，或减少心肌灌注。通过心肌灌注成像（MPI）进行的生理负荷试验是评价CAD的传统方法，可识别缺血但不能识别狭窄。相比之下，冠状动脉CT血管造影术（CCTA）能够直接解剖可视化CAD，但不能区分狭窄是否导致缺血。 通过侵入性方法，分别通过侵入性冠状动脉造影术和血流储备分数（FFR）进行CAD评价的联合解剖-生理方法可改善对导致缺血的狭窄患者的诊断，减少不必要的血运重建，并改善临床结局。最近，通过将CT灌注（CTP）添加到CCTA中，通过非侵入性方法结合解剖-生理方法已成为可能。与MPI类似，CTP允许通过测量局部心肌信号衰减对狭窄进行生理评估。CTP的早期研究受到几个局限性的限制，包括：1）阴影伪影; 2）运动伪影; 3）缺乏评估灌注的定量方法; 4过度辐射;以及5）无法精确定位导致缺血的特定病变。 投影 基于双能量CT（DECT）的双能CT是一种新型CT技术，直接解决了许多这些限制，提供了显着减少伪影和定量测量心肌灌注的潜力。再加上时间分辨率的提高，减少运动伪影，DECT有可能提高CTP的诊断准确性，无疑对目前疑似CAD患者的诊断方法产生积极和重大的影响。该提案的总体假设是，一种新的基于定量投影的基于DECT的方法将能够区分患有心肌缺血的个体以及识别作为原因的特定冠状动脉病变。本研究有3个具体目的：1）开发一种可准确量化材料密度的新型DECT方法; 2）确定新型DECT方法表征心肌灌注的体外诊断准确性; 3）与有创FFR“金”标准相比，通过新型DECT方法评价CTP的体内诊断准确性，以确定冠状动脉病变特异性缺血。

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.