Evaluation of Myocardial Perfusion by Computed Tomography - Principles, Technical Background and Recommendations

Abstract Coronary computed tomography angiography (CCTA) has gained a prominent role in the evaluation of coronary artery disease. However, its anatomical nature does not allow the evaluation of the functional repercussion of coronary obstructions. It has been made possible to evaluate Myocardial computed tomography perfusion (Myocardial CTP) recently, based on myocardial contrast changes related to coronary stenoses. Several studies have validated this technique against the anatomical reference method (cardiac catheterization) and other functional methods, including myocardial perfusion scintigraphy and fractional flow reserve. The Myocardial CTP is performed in conjunction with the CCTA, a combined analysis of anatomy and function. The stress phase (with assessment of myocardial perfusion) can be performed before or after the resting phase (assessment of resting perfusion and coronary arteries), and different acquisition parameters are proposed according to the protocol and type of equipment used. Stressors used are based on coronary vasodilation (e.g. dipyridamole, adenosine). Image interpretation, similar to other perfusion assessment methods, is based on the identification and quantification of myocardial perfusion defects. The integration of both perfusion and anatomical findings is fundamental for the examination interpretation algorithm, allowing to define if the stenoses identified are hemodynamically significant and may be related to myocardial ischemia.

摘要 冠状动脉计算机断层血管造影（Coronary computed tomography angiography, CCTA）在冠状动脉疾病的评估中已占据重要地位。然而，其解剖学成像特性无法评估冠状动脉阻塞带来的功能学影响。近年来，基于与冠状动脉狭窄相关的心肌对比剂变化，心肌计算机断层灌注（Myocardial computed tomography perfusion, CTP）的评估已成为可能。多项研究已将该技术与解剖学参考方法（心导管术）及其他功能学评估方法（包括心肌灌注显像与血流储备分数）进行了对照验证。心肌CTP通常与CCTA联合开展，实现解剖结构与功能状态的联合分析。负荷相（用于评估心肌灌注）可在静息相（用于评估静息状态下的心肌灌注与冠状动脉）之前或之后进行，具体采集参数需根据检查方案与所用设备类型进行调整。常用的负荷诱导剂基于冠状动脉血管扩张原理（如双嘧达莫、腺苷）。与其他灌注评估方法类似，图像解读需基于心肌灌注缺损的识别与量化。将灌注结果与解剖学发现相结合，是该检查解读流程的核心环节，可用于明确所识别的狭窄是否具有血流动力学意义，以及是否与心肌缺血相关。