Schmermund A, Bell M R, Lerman L O, Ritman E L, Rumberger J A
Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic and Foundation, Rochester, MN, USA.
Herz. 1997 Feb;22(1):29-39. doi: 10.1007/BF03044568.
Clinical quantitation of regional myocardial perfusion using a minimally invasive and easily applied technique could allow for ready quantitation of the functional significance of coronary disease, allow for further understanding of flow reserve in various cardiomyopathic and hemodynamic overload (pressure versus volume) conditions, and possibly provide basic information needed regarding the development and clinical significance of coronary collateral vessels and diseases of the myocardial microcirculation. Electron beam CT (EBCT) is a unique cardiac imaging modality that allows for rapid acquisition tomographic slices of the heart with excellent spatial resolution. It has been demonstrated to provide accurate measurements of cardiac anatomy, biventricular function, myocardial mass, and estimates of mural atherosclerotic plaque burden via quantification of coronary calcium. The application of classical indicator techniques for use by fast x-ray computed tomography techniques such as electron beam CT has been shown to allow quantitative analysis of regional myocardial perfusion throughout the myocardium. Initial studies using central intravenous contrast injection in experimental animals showed a close correlation of regional myocardial perfusion as quantitated by electron beam CT with measurements using radiolabeled microspheres at resting and moderately increased flow states. At high flow states, however, electron beam CT significantly underestimated absolute myocardial perfusion and thus myocardial flow reserve. Using another fast CT device, the Dynamic Spatial Reconstructor (DSR), concepts of intramyocardial vascular blood volume and its relation to myocardial flow have been established. By adapting these concepts to electron beam CT scanning and accounting for the increase in intramyocardial vascular blood volume at vasodilatation, the ability to correctly quantitate perfusion states up to approximately 400 mL.min-1. 100 g-1 using central intravenous contrast administration was demonstrated. This implies that studies can be done with intravenous injection methods for characterization of regional myocardial perfusion up to the normal flow reserve of approximately 4:1. Important physiologic and clinical abnormalities in flow reserve generally result in a ratio < 3:1. Electron beam CT offers the capability to quantitate regional myocardial perfusion in both the clinical and research setting. Of particular interest is the ability to provide quantitative regional myocardial perfusion which can be coupled to the evaluation of cardiac anatomy and function as well as mural coronary atherosclerotic calcium burden during the same scanning session. Thus, electron beam CT has the potential to become a valuable, minimally invasive clinical tool for comprehensive analysis of cardiac function and coronary status.
使用微创且易于应用的技术对局部心肌灌注进行临床定量分析，能够对冠心病的功能意义进行便捷定量，有助于进一步了解各种心肌病和血流动力学超负荷（压力与容量）情况下的血流储备，并可能提供有关冠状动脉侧支血管发育及临床意义以及心肌微循环疾病所需的基础信息。电子束CT（EBCT）是一种独特的心脏成像方式，能够以出色的空间分辨率快速获取心脏的断层切片。已证实它可通过冠状动脉钙化定量准确测量心脏解剖结构、双心室功能、心肌质量，并估算壁内动脉粥样硬化斑块负荷。将经典指示剂技术应用于电子束CT等快速X射线计算机断层扫描技术，已显示可对整个心肌的局部心肌灌注进行定量分析。最初在实验动物中使用中心静脉注射造影剂的研究表明，在静息和中等血流增加状态下，电子束CT定量的局部心肌灌注与使用放射性标记微球测量的结果密切相关。然而，在高血流状态下，电子束CT显著低估了绝对心肌灌注，从而低估了心肌血流储备。使用另一种快速CT设备——动态空间重建仪（DSR），已确立了心肌内血管血容量及其与心肌血流关系的概念。通过将这些概念应用于电子束CT扫描，并考虑血管扩张时心肌内血管血容量的增加，证明了使用中心静脉注射造影剂能够正确定量高达约400 mL·min⁻¹·100 g⁻¹的灌注状态。这意味着可以采用静脉注射方法进行研究，以表征局部心肌灌注直至约4:1的正常血流储备。血流储备中重要的生理和临床异常通常导致比值<3:1。电子束CT具备在临床和研究环境中对局部心肌灌注进行定量的能力。特别值得关注的是，它能够在同一次扫描过程中提供可与心脏解剖结构和功能评估以及冠状动脉壁粥样硬化钙负荷评估相结合的定量局部心肌灌注。因此，电子束CT有潜力成为一种用于心脏功能和冠状动脉状况综合分析的有价值的微创临床工具。
