HIGH RESOLUTION MRI OF MYOCARDIAL DEFORMATION

心肌变形的高分辨率MRI（竞争更新 应用）。在这项赠款的第一个资助期内， 新的成像和分析技术， 心肌应变与前所未有的空间分辨率在整个 左心室这些方法都经过了严格的优化和验证 通过模拟和实验。开发的方法， 实现高空间分辨率已经立即导致稳健的临床应用， 目前用于描述正常和缺血性 人类的心脏在这个项目的下一阶段，我们计划扩大我们的高 空间分辨率技术转化为高时间分辨率技术， 目的是测量异位电激活 以及正常、缺血和衰竭心脏的机械收缩。 我们的初步数据表明，我们可以解决心肌“脉冲”， 从起搏部位发出的收缩， 心脏的另一面是心室，并会聚在心脏的另一面。这 传播发生在起搏刺激后的150 ms期间， 速度取决于方向。 我们计划调查 心肌的机械和电性能，通过追求 以下具体目标：（1）开发新的成像序列 空间和时间分辨率来测量机械传播 在心室起搏期间三维收缩。(2)开发图像 分析方法，将新的标记模式纳入高时间 的时空力学行为的分辨率估计， 心这些新功能将用于回答以下问题 心脏生理学的基本问题：（3）什么是心脏的模式？ 心室上不同起搏部位的机械激活？(4)如何 缺血区域的存在是否改变了这种机械性的 激活？[(5)起搏引起增强的机制是什么 扩张型心肌病患者的心腔功能这 心脏成像方法的发展将为我们提供新的工具来回答 关于心室功能的基本问题，例如 机械预牵拉引起心律失常，起搏电极的影响 用于改善衰竭心脏的心室性能，以及 各地区对外工作的重新分配 心脏。]

High Resolution MRI of Myocardial Deformation (competing renewal application). In the first funding period of this grant we have developed novel imaging and analysis techniques for acquiring measurements of myocardial strain with unprecedented spatial resolution over the entire left ventricle. These methods have been rigorously optimized and validated with simulations and experiments. The methods which were developed to achieve high spatial resolution have lead immediately to robust clinical protocols that are now being used to characterize the normal and ischemic human heart. In this next phase of the project we plan to extend our high spatial resolution techniques into high temporal resolution techniques with the goal to measure the relationship between ectopic electrical activation and mechanical contraction in the normal, ischemic, [and failing] heart. Our preliminary data show that we can resolve a "pulse" of myocardial contraction that emanates from a pacing site, travels around the left ventricle, and converges on the opposite wall of the heart. This propagation occurs during the l50ms after the pacing stimulation and the velocity is direction dependent. We plan to investigate the interaction of the mechanical and electrical properties of myocardium by pursuing the following specific aims: (1) Develop novel imaging sequences with the spatial and temporal resolution to measure the propagation of mechanical contraction in 3 dimensions during ventricular pacing. (2) Develop image analysis methods to incorporate new tagging patterns into the high temporal resolution estimates of the spatial-temporal mechanical behavior of the heart. These new capabilities will be used to answer the following fundamental questions of cardiac physiology: (3) What is the pattern of mechanical activation for different pacing sites on the ventricle? (4) How does the existence of an ischemic region alter this pattern of mechanical activation?. [(5) What is the mechanism by which pacing causes enhanced cardiac chamber function in hearts with dilated cardiomyopathy? This development in cardiac imaging methods will give us new tools to answer fundamental questions about ventricular function, such as the role of mechanical prestretch in causing arrhythmia, the effect of pacing lead placement on improving ventricular performance in the failing heart, and the redistribution of external work done by individual regions of the paced heart.]