基于仿真流体力学建立冠状动脉缺血性狭窄双能量CT功能评价指标的实验和临床研究

Stent implantation for patients with coronary artery disease (CAD) must be the premise of patients with moderate or severe stenosis of imaging evaluation and also the evidence of myocardial ischemia. This is because both the clear presence of myocardial ischemia of invasive coronary blood fractional flow reserve score (FFR) and the noninvasive fractional flow reserve computed from coronary computed tomography angiography (FFR-CT) are expensive, time-consuming, and can not be used routinely. Hence, the vast majority of patients with only a narrow evaluation to determine whether to stent implantation, but anatomical narrow doesn't always indicate ischemia and operation doesn't always benefit patients. The latest study confirms that there is transluminal attenuation gradient (TAG) exists inside oronary arteries and the TAG and some CT ratios are correlated with the degree of stenosis and ischemic stenosis. Can we get some functional evaluation index similar with FFR-CT based on these? The basis of hemodynamic changes and the prediction threshold of functional stenosis is not fully clear. This study plans to make up simulated biological fluid mechanics stenosis model of coronary artery in vitro, to obtain the variance and the definite ratios of homeostasis intravascular CT attenuation values with dual energy CT, and further to validate the result by using imaging coronary artery stenosis model, and finally applied to evaluate patients. With the SPECT and FFR as the reference standard，to obtain functional assessment indicator, which can predeterminate ischemic stenosis of coronary artery, and also to test their accuracy. Prospected results are expected to expand the studies of CT coronary artery functional imaging, to guide rational stent implantation and ultimately benefit patients.

冠心病患者行支架置入术必须有狭窄的影像学评价并获得心肌缺血证据，但测定心肌缺血的有创性血流储备分数(FFR)及无创性CT血流储备分数（FFR-CT）均因昂贵、耗时而无法广泛应用，故目前绝大多数手术仅取决于影像学狭窄评价，但狭窄≠缺血，手术未必使患者受益。最新的CT功能研究发现，冠状动脉内CT值变化梯度及特定比值与狭窄程度相关，并可能与缺血性狭窄相关。但在此基础上是否能得到类似FFR-CT的功能评价指标？其血流动力学改变依据及致缺血性狭窄的重要CT阈值等尚不清楚。本研究拟体外构建仿真生物流体力学冠脉狭窄模型，经双能量CT获得稳态血管内CT值变化规律及特定比值，再以猪冠状动脉狭窄模型的CT双能量成像进一步验证，最终应用于患者，以SPECT心肌灌注和FFR为参考，得到能预测缺血性狭窄的功能评价指标并验证其准确性。预期结果有望拓展冠状动脉CT的功能成像研究，广泛指导支架的合理置入，最终使患者受益。

冠心病患者行支架置入术必须有狭窄的影像学评价并获得心肌缺血证据，但测定心肌缺血的有创性血流储备分数(FFR)及无创性CT血流储备分数（FFR-CT）均因昂贵、耗时而无法广泛应用，故目前绝大多数手术仅取决于影像学狭窄评价，但狭窄≠缺血，手术未必使患者受益。最新的CT功能研究发现，冠状动脉内CT值变化梯度及特定比值与狭窄程度相关，并可能与缺血性狭窄相关。本研究通过体外构建仿真生物流体力学冠状动脉狭窄模型（75%和90%），明确了狭窄血管内剪切压力分布情况；经双源CT双能量扫描在动物体内获得血管内CT值，发现TAG值与冠脉的狭窄程度呈正比。进一步人体研究发现TAG确实与冠脉解剖狭窄成正比，并可提高CCTA对狭窄程度的诊断能力；而对于影响狭窄程度评估的钙化病变，TAG可有效提高狭窄程度再分类；当以FFR为金标准时，TAG可在一定程度上反映冠脉缺血性狭窄。

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