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.

冠状动脉计算机断层扫描血管造影（CCTA）在冠状动脉疾病评估中占据了显著的地位。然而，由于其解剖特性，无法评估冠状动脉阻塞的功能性影响。近期，基于与冠状动脉狭窄相关的心肌对比变化，已能够对心肌计算机断层扫描灌注（Myocardial CTP）进行评估。多项研究已验证该技术相对于解剖学参考方法（心脏导管检查）及其他功能性方法，包括心肌灌注闪烁扫描和血流储备分数的有效性。Myocardial CTP的执行与CCTA相结合，实现了解剖与功能的综合分析。应激相（评估心肌灌注）可以在静息相（评估静息灌注和冠状动脉）之前或之后进行，并根据协议和所使用设备的类型提出不同的采集参数。所使用的应激剂基于冠状动脉扩张（例如，双嘧达莫，腺苷）。图像解读，类似于其他灌注评估方法，基于心肌灌注缺陷的识别和量化。将灌注和形态学发现相结合对于检查解读算法至关重要，使得能够定义所识别的狭窄是否具有血流动力学意义，并可能与心肌缺血相关。