Dual Energy Computed Tomography for Determining Coronary Lesion-Specific Ischemia

描述（由申请人提供）：本申请的总体目标是开发一种新的定量计算机断层扫描（CT）方法，用于精确识别引起缺血的冠状动脉病变。目前，还没有一种无创检测方法既能确定冠心病（CAD）狭窄的严重程度，又能确定狭窄是否导致心肌缺血或灌注减少。通过心肌灌注成像（MPI）进行生理应激测试是评估CAD的传统方法，它可以识别缺血但不能识别狭窄。相比之下，冠状动脉CT血管造影（CCTA）可以直接显示CAD的解剖结构，但不能区分狭窄是否导致缺血。通过有创方法，解剖-生理相结合的方法分别通过有创冠状动脉造影和分数血流储备（FFR）来评估CAD，提高了对引起缺血的狭窄患者的诊断，减少了不必要的血运重建，改善了临床结果。最近，通过在CCTA中加入CT灌注（CTP），一种无创的解剖-生理结合的方法成为可能。与MPI类似，CTP允许通过测量局部心肌信号衰减来对狭窄进行生理评估。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)缺乏定量评估灌注的方法；4 .过量辐射；5)无法精确定位导致缺血的特定病变。投影

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.