Multidimensional Heart Imaging With Ultrasound

描述（由申请人提供）：舒张功能障碍是指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力代偿性增加，以维持卒中容量。这种情况通常与心壁硬度增加有关。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，用于定量和无创的高时间和空间分辨率活检样心肌力学特性测量，特别是体内心脏壁的各向异性粘弹性模量。这种新方法，我们称之为振动测量法，利用聚焦超声束的辐射压力来刺激横波沿着感兴趣区域内的适当轴的形成和传播。用脉冲多普勒、b扫描相关或我们的新卡尔曼方法测量横波的速度和频散。在所研究的特定几何结构中，波传播的数学模型将用于解析或使用先进的逆有限元方法求解相关力学特性，如各向异性粘弹性模量。模型将通过独立的体外和体内测量进行验证。在对假体和切除心脏的初步研究中，该方法已被证明能够快速、准确和无创地测量切除心肌和横纹肌纤维上的剪切模量的弹性（mu1）和粘性（mu2）项。该计划的目标将通过四个具体目标来实现。目标1：在一个越来越复杂的理论的顺序发展中，我们将推导出在心脏壁的一点或直线上的谐波或脉冲辐射力与由此引起的附近传播波位移之间的解析数学关系。目标2：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幻影和组织中产生的动态应变随时间和空间的变化，以验证目标1中开发的反解。目标3：目标1和目标2的理论和方法将在离体灌注跳动和非跳动心脏中进行测试。商业扫描仪将被修改以进行振动测量。目标4：振动测量将扩展到闭胸猪，预期临床应用。该计划的成功完成将产生测量人类机械心壁特性的技术和程序，为评估与心壁刚度改变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.