Multidimensional Heart Imaging With Ultrasound

描述（由申请人提供）：舒张功能障碍是左心室在生理压力下充盈的能力受损，通常导致心房充盈压代偿性增加以维持每搏输出量。这种情况通常与心脏壁的硬度增加有关。超声心动图通过将各种测量结果与临床信息相结合，可以提供最全面的心脏舒张功能信息。下一个资助周期的目标是生产超声设备和技术，用于定量和非侵入性的高时间和空间分辨率活检样测量心肌机械性能，特别是体内心脏壁的各向异性粘弹性模量。我们称之为振动测量的新方法，使用聚焦超声束的辐射压力来刺激剪切波的形成和传播，使其沿着感兴趣区域内的适当轴。剪切波的速度和色散是用脉冲多普勒、B扫描相关或我们新的卡尔曼方法测量的。在特定的几何形状的波的传播的数学模型正在研究将被用来解决解析或先进的逆有限元方法的相关机械性能，如各向异性粘弹性模量。将通过独立的体外和体内测量对模型进行确认。在幻影和切除心脏的初步调查的方法已被证明是能够执行快速，准确和非侵入性测量的弹性（μ 1）和粘性（μ 2）条款的剪切模量沿着和跨切除心肌和横纹肌的肌纤维。该计划的目标将通过四个具体目标来实现。目标1：在日益复杂的理论的顺序发展中，我们将推导出心脏壁中的点或线处的谐波或脉冲辐射力与由该力引起的附近传播波位移之间的解析数学关系。目标二：我们将使用谐波和脉冲辐射力方法来诱导运动，并使用高精度方法来测量体模和组织中产生的动态应变与时间和空间的关系，以验证目标1中开发的逆解。目的3：将在离体灌注跳动和非跳动心脏中测试目的1和2的理论和方法。将对商业扫描仪进行修改，以进行振动测量。目的4：将振动测量法扩展到闭胸猪，以期待临床应用。该计划的成功完成将导致测量人体心脏壁力学特性的技术和程序，为评估与心脏壁硬度变化相关的心脏异常提供工具。

DESCRIPTION (provided by applicant): Diastolic dysfunction is the impaired ability of the left ventricle to fill at physiologic pressures, often resulting in a compensatory increase of atrial filling pressures to maintain the stroke volume. This condition is usually associated with increased stiffness of the heart wall. Echocardiography can provide the most comprehensive information on diastolic function of the heart by integrating a variety of measurements with the clinical information. The goals of the next grant cycle are to produce ultrasound apparatus and techniques for quantitative and noninvasive high temporal and spatial resolution biopsy-like measurement of myocardial mechanical properties, specifically the anisotropic visco-elastic moduli of the heart wall in vivo. The new method, which we call vibrometry, uses radiation pressure of a focused ultrasound beam to stimulate formation and propagation of shear waves along the appropriate axes within the region of interest. The velocity and dispersion of the shear wave is measured with pulsed Doppler, B-scan correlation, or our new Kalman method. Mathematical models for the propagation of the wave in the particular geometry being studied will be used to solve analytically or with advanced inverse finite element methods for relevant mechanical properties such as the anisotropic visco-elastic moduli. Models will be validated with independent in vitro and in vivo measurements. In preliminary investigations of phantoms and excised hearts the method has been shown to be capable of performing fast, accurate and noninvasive measurements of the elastic (mu1) and viscous (mu2) terms of the shear modulus along and across the myofibers of excised myocardium and striated muscle. The goals of this program will be achieved through four Specific Aims. Aim 1: In a sequential development of increasingly complex theories, we will derive the analytic mathematical relationships between harmonic or impulse radiation force at a point or line in the heart wall and the resulting nearby propagating wave displacements caused by the force. Aim 2: We will use harmonic and impulse radiation force methods to induce motion and high precision methods to measure the resulting dynamic strain versus time and space in phantoms and tissues to validate the inverse solutions developed in Aim 1. Aim 3: Theory and methods from Aims 1 and 2 will be tested in isolated perfused beating and non beating hearts. A commercial scanner will be modified to make vibrometry measurements. Aim 4: Vibrometry will be extended to closed chest pigs in anticipation of clinical application. Successful completion of this program will result in techniques and procedures for measuring mechanical heart wall properties in humans providing a tool for evaluating cardiac abnormalities associated with alterations in heart wall stiffness.