INTEGRATED MRI EXAM OF FLOW RESERVE

本研究的目的是验证和优化一个集成的 磁共振（MR）方法可以无创地 测定冠状动脉血流储备和心肌氧合， 缺血性心脏病 我们的真实的时间MR方法使用 飞行时间（TOF）冠状动脉同步采集 速度测量和血氧水平依赖 （BOLD）心肌氧合评估。 我们改进的飞行时间 磁共振断层扫描方法测量冠状动脉血流速度， 流动的血液产生的内在对比。 我们的初步 数据显示血管扩张剂治疗期间冠状动脉储备指数正常 正常志愿者的挑战，以及 阻塞性冠状动脉病变患者。 以下优化 在动物中，将在正常志愿者和 局灶性冠状动脉疾病（CAD）患者，多普勒 后者的流量储量相关性。 冠状动脉的生理意义的表征 病变将通过同时采集图像来增强 对心肌耗氧量的变化敏感。 我们将 利用MR的固有敏感性， 脱氧血红蛋白含量，从而产生T2* 对比。 这 心脏中的磁化率对比取决于许多参数 包括冠状动脉流量、血红蛋白含量、冠状静脉 体积和局部心肌代谢（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化为 局部生理变量的变化。 我们将联合收割机 计算机模拟，已经证明成功的， 解释MR变化与大脑激活，与新的 实验上孤立的血液灌注热，使用EPI，以 在体内量化这些变化。 一旦优化， 将在正常志愿者和 局灶性冠状动脉疾病患者，使用正电子发射 断层扫描（PET）用于后者的比较。 我们的总体目标是改善 心脏的宏观和微观血液供应， 更好地理解冠状动脉血流限制在 缺血性心脏病的发病机制和临床演变。 的 这项研究的长期目标是开发一种协议， 将这些方法集成到单个心脏MR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.