NMR STUDIES OF MYOCARDIAL PERFUSION

该项目的总体目标是开发和验证新的 接近量化局部心肌灌注和流量 储备使用固有的核磁共振对比，并确定效用 这些技术在检测冠状动脉疾病（CAD）。 天然橡胶技术的新进展和新发现 关于对MR图像对比度的贡献可以允许 心脏的最小或完全非侵入性测量 灌注和局部心肌功。实验支持 这个PPG和其他人已经证明， 血氧影响纵向（T1）和横向（T2） 放松的时间在心中。 灌注变化直接改变T1。 静脉血氧合的变化，来自耦合 在流动和功能之间改变T2 虽然一些早期的 对大脑的工作（项目1）可以扩展到心脏， 心脏研究具有独特的挑战性，因为一般 测量一个不断运动的物体中微小变化的问题 器官. 本征核磁共振变化与 潜在生理学由于各种其他因素而变得复杂 微观和宏观过程。这项研究将 研究其中的几种影响，包括内部/外部的作用， 血管水交换，利用磁化传递效应 的T1措施的流动，不断变化的磁环境， 心跳;以及由于以下原因导致的较长回波时间的人为变化 心肌图像对比度上的血流失相。我们试图利用 这些变化，以产生定量地图的结果， 使用血管舒张剂（腺苷和 多巴酚丁胺）激发的冠状动脉损伤 狭窄和心肌顿抑。 我们假设 局部T1和T2* 加权图像增强 血管舒张直接与局部变化相关， 微球测量流量。 研究将在 使用腺苷激发的疑似CAD患者， 确定用于检测的固有NMR对比度的灵敏度 与N13氨PET相比，具有生理学意义的CAD 测量.

The overall goal of this project is to develop and validate novel approached to quantify local myocardial perfusion and flow reserve using intrinsic NMR contrast and to determine the utility of these techniques in detecting coronary artery disease (CAD). Recent advances in NR technology and recent discoveries regarding contributions to MR image contrast may allow minimally or completely non-invasive measurement of heart perfusion and local myocardial work. Experiments supported by this PPG and others have demonstrated that changes in flow and blood oxygenation affect the longitudinal (T1) and transverse (T2) relaxation times in the heart. Perfusion changes directly alter T1. Changes in venous blood oxygenation, derived from the coupling between flow and function, alter T2. Though some of the earlier work on the brain (Projects 1) can be extended to the heart, cardiac studies are uniquely challenging because of the general problem of measuring small changes in a constantly moving organ. The relationship between the intrinsic NMR changes and the underlying physiology is complicated by a variety of other microscopic and macroscopic processes. This research will investigate several of these effects including the role intra/extra- vascular water exchange, the use of magnetization transfer effects of T1 measures of flow, the changing magnetic environment as the heart beats; and artifactual changes at longer echo times due to flow dephasing on myocardial image contrast. We seek to exploit these changes to produce quantitative maps of the results of pharmacological stress using vasodilatory (adenosine and dobutamine) challenge in intact porcine models of coronary artery stenosis and myocardial stunning. We hypothesize that the degree of local T1 and T2*-weighted image enhancement during vasodilation correlates directly with the local change in microsphere-measured flow. Studies will then be performed in patients with suspected CAD using adenosine challenge to determine the sensitivity of intrinsic NMR contrast for detecting physiologically significant CAD compared to N13 ammonia PET measurements.