INTEGRATED MRI EXAM OF FLOW RESERVE

本研究的目标是验证和优化集成的 磁共振(MR)方法，可以无创地 冠状动脉血流储备和心肌氧合功能的测定 缺血性心脏病。我们的实时mr方法使用 冠状动脉飞行时间(TOF)的同步采集 血流速度测量和血氧水平依赖 (BOLD)评估心肌氧合情况。我们改进的TOF 磁共振断层扫描方法测量冠状动脉血流速度 流动的血液所产生的内在对比。我们的预赛 数据显示血管扩张剂期间冠状动脉储备指数正常 正常志愿者的挑战和异常的血流反应 有梗阻性冠状动脉病变的患者。后续优化 在动物身上，数据将在正常志愿者和 局灶性冠状动脉病变(CAD)患者的多普勒 后者为流动储量对比。 冠脉病变生理意义的表征 病变将通过同时采集图像来增强 对心肌耗氧量变化敏感。我们会 利用MR对变化的内在敏感性 脱氧血红蛋白含量，从而产生T2*对比度。这 心脏的磁化率对比取决于可能的参数 包括冠脉流量、血红蛋白含量、冠脉静脉 容量和局部心肌代谢(耗氧量)。 我们将发展理论和实验技术。 需要将我们在MR图像中观察到的变化转换为 局部生理变量的变化。我们将联合起来 计算机模拟，已经被证明是成功的 用大脑激活来解释磁共振变化，用新奇的 利用EPI对隔离血液灌流的体温进行实验 在活体内量化这些变化。优化后，区域数据 在正常受试者和受试者中均可获得心肌灌注。 局灶性冠状动脉疾病患者的正电子发射 体层摄影术(PET)对后者进行比较。 我们的总体目标是改善 心脏的宏观和微观供血并获得 更好地了解冠脉血流受限在冠状动脉病变中的作用 缺血性心脏病的发病机制及临床演变。这个 这项研究的长期目标是开发一种协议， 将这些方法整合到一次心脏磁共振检查中。

The goal of this research is to validate and optimize an integrated magnetic resonance (MR) approach that can noninvasively determine coronary flow reserve and myocardial oxygenation in ischemic heart disease. Our real time MR approach uses the simultaneous acquisition of time-of-flight (TOF) coronary artery velocity measurements and blood-oxygenation level dependent (BOLD) assessment of myocardial oxygenation. Our modified TOF MR tomographic approach measures coronary flow velocity using the intrinsic contrast generated by flowing blood. Our preliminary data demonstrate normal coronary reserve index during vasodilator challenge in normal volunteers, and abnormal flow responses in patients with obstructive coronary lesions. Following optimization in animals, data will be acquired in normal volunteers and in patients with focal coronary artery disease (CAD), with Doppler flow reserve correlation in the latter. Characterization of the physiological significance of coronary lesions will be enhanced by the simultaneous acquisition of images sensitive to changes in myocardial oxygen consumption. We will exploit the intrinsic sensitivity of MR to changes in deoxyhemoglobin content, thereby producing T2*contrast. This susceptibility contrast in the heart depends on may parameters including coronary flow, hemoglobin content, coronary venous volume, and local myocardial metabolism (oxygen consumption). We will develop both the theory and experimental techniques required to translate the changes we observe in MR images into changes in local physiological variables. We will combine computer simulations, that have already proven successful in explaining MR changes with brain activation, with novel experiments on isolated blood-perfused heats, using EPI in order to quantify these changes in vivo. Once optimized, data on regional myocardial perfusion will be acquired in normal volunteers and in patients with focal coronary disease, using positron emission tomography (PET) for comparison on the latter. Our overall objectives are both to improve imaging of the macroscopic and microscopic blood supply of the heart and to gain a better understanding of the role of coronary flow limitation in the pathogenesis and clinical evolution of ischemic heart disease. The long term goal of this research is to develop a protocol that integrates these approaches into a single cardiac MR exam.