Division of Nuclear Medicine, Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD.
Division of Cardiology, Department of Specialties in Medicine, University Hospitals of Geneva, Geneva, Switzerland.
Semin Nucl Med. 2014 Jul;44(4):274-93. doi: 10.1053/j.semnuclmed.2014.04.002.
Myocardial perfusion imaging with SPECT/CT or with PET/CT is a mainstay in clinical practice for the diagnostic assessment of downstream, flow-limiting effects of epicardial lesions during hyperemic flows and for risk stratification of patients with known or suspected coronary artery disease (CAD). In patients with multivessel CAD, the relative distribution of radiotracer uptake in the left ventricular myocardium during stress and rest accurately identifies flow-limiting epicardial lesions or the most advanced, so called culprit, lesion. Often, less severe obstructive CAD lesions may go undetected or underdiagnosed. The concurrent ability of PET/CT with radiotracer kinetic modeling to determine myocardial blood flow (MBF) in absolute terms (mL/g/min) at rest and during vasomotor stress allows the computation of regional myocardial flow reserve (MFR) as an adjunct to the visual interpretation of myocardial perfusion studies. Adding the noninvasive evaluation and quantification of MBF and MFR by PET imaging to the visual analysis of myocardial perfusion may (1) identify subclinical CAD, (2) better characterize the extent and severity of CAD burden, and (3) assess "balanced" decreases of MBF in all 3 major coronary artery vascular territories. Recent investigations have demonstrated that PET-determined reductions in hyperemic MBF or MFR in patients with subclinical or clinically manifest CAD are predictive of increased relative risk of future cardiovascular events and clinical outcome. Quantifying MFR with PET enables the identification and characterization of coronary vasodilator dysfunction as functional precursor of the CAD process, which offers the unique opportunity to monitor its response to lifestyle or risk factor modification by preventive medical care. Whether an improvement or even normalization of hyperemic MBF or the MFR in subclinical or in clinically manifest CAD confers an improved long-term cardiovascular outcome remains untested. Nonetheless, given the recent growth in the clinical utilization of myocardial perfusion PET, image-guided and personalized preventive care of vascular health may become a reality in the near future.
单光子发射计算机断层扫描/计算机断层扫描（SPECT/CT）或正电子发射断层扫描/计算机断层扫描（PET/CT）心肌灌注显像是临床实践中诊断评估冠状动脉疾病（CAD）患者心外膜病变在充血性血流期间下游、限制血流的效应和风险分层的主要手段。在多支血管 CAD 患者中，左心室心肌在应激和休息期间放射性示踪剂摄取的相对分布准确识别限制血流的心外膜病变或最严重的、所谓的罪犯病变。通常，较轻的阻塞性 CAD 病变可能无法检测或漏诊。PET/CT 结合放射性示踪剂动力学模型能够确定静息和血管舒缩应激期间心肌血流（MBF）的绝对值（mL/g/min），从而计算区域心肌血流储备（MFR），作为心肌灌注研究的视觉解释的辅助手段。通过 PET 成像对 MBF 和 MFR 的无创评估和定量，将其添加到心肌灌注的视觉分析中，可能（1）识别亚临床 CAD，（2）更好地描述 CAD 负担的程度和严重程度，以及（3）评估所有 3 个主要冠状动脉血管区域的 MBF 的“平衡”下降。最近的研究表明，在亚临床或临床表现 CAD 患者中，PET 确定的充血性 MBF 或 MFR 降低与未来心血管事件和临床结果的相对风险增加相关。使用 PET 定量 MFR 可识别和描述冠状动脉扩张功能障碍作为 CAD 过程的功能前体，为通过预防保健监测其对生活方式或危险因素改变的反应提供了独特的机会。亚临床或临床表现 CAD 中的充血性 MBF 或 MFR 改善甚至正常化是否可带来改善的长期心血管结局仍未得到检验。尽管如此，鉴于心肌灌注 PET 在临床应用中的最近增长，血管健康的图像引导和个性化预防保健可能在不久的将来成为现实。
