HIGH RESOLUTION MRI OF MYOCARDIAL DEFORMATION

心肌变形的高分辨率磁共振成像(竞争性更新 申请)。在这笔赠款的第一个资助期，我们制定了 用于获取测量结果的新成像和分析技术 以前所未有的空间分辨率在整个 左心室。这些方法经过了严格的优化和验证 通过模拟和实验。开发的方法是为了 达到高空间分辨率立即带来了强大的临床 现在被用来描述正常和缺血的方案 人类的心脏。在这个项目的下一阶段，我们计划延长我们的高度 空间分辨率技术转化为高时间分辨率技术 测量异位电激活之间关系的目标 以及正常、缺血和衰竭心脏的机械性收缩。 我们的初步数据显示，我们可以分辨出心肌的“脉搏” 从起搏部位发出的收缩，围绕左侧传播 并汇聚在心脏的对面壁上。这 起搏刺激后150毫秒内发生传播， 速度与方向有关。我们计划调查这种相互作用 通过研究心肌的机械和电学特性 具体目标如下：(1)开发新的成像序列 用空间和时间分辨率测量机械波的传播 心脏起搏时的三维收缩。(二)塑造形象 将新的标注模式融入高时态的分析方法 空间-时间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)心脏生理学的模式 心室不同起搏部位的机械激活？(4)如何 缺血区的存在会改变这种机械运动模式吗？ 激活？[(5)起搏引起增强的机制是什么 扩张型心肌病心脏的心腔功能？这 心脏成像方法的发展将给我们提供新的工具来回答 关于心功能的基本问题，如心脏的作用 机械预拉伸对起搏电极致心律失常的影响 在衰竭的心脏中放置改善心脏功能的药物，以及 由起搏器的各个区域所做的外部功的重新分配 心。]

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.]