ANISOTROPY IN MYOCARDIAL ULTRASOUND

拟议研究的最终目的是阐明 使用超声波的物理原理在确定 优化心肌声学特性所需的定量方法 功能的诊断和评估。在临床超声心动图中， 扫描是随着超声波传播方向的变化而进行的 与心肌局部纤维取向的夹角 在整个收缩-松弛循环中。我们已经证明了 后向散射和衰减的大小随 肌纤维排列的相对光化角度 室壁。各向异性是造成这种现象的原因 胸骨旁短轴的侧壁和隔壁回声 超声心动图观察，尤其适用于定量 组织特征化的目标是评估 组织本身的属性，与尺寸评估相反 也不是运动。我们建议继续并扩大我们的系统 超声角变化幅度的研究 心脏的特性及其与传统的关系 超声心动图，自动超声心动图检测组织血液 界面，心肌组织特征，并最终达到 超声评价心肌弹性特性。研究过程中 目前的授权期侧重于各向异性属性的平均 超过整个室壁的厚度。在这场竞争中 更新建议，我们概述了旨在描绘跨壁画的研究 与显著透壁平行的弹性性质的变化 正常人和病变者的三维结构变化 通过测量心肌各向异性的跨壁变化 心肌的背向散射、衰减和速度并与 适当的实验和数学模型。我们进一步建议 克服潜在绊脚石的策略 超声心动图的各向异性，心脏的自动检测 心腔大小和心肌组织特征。建议数 研究旨在为利用各向异性奠定基础 以提高对心肌弹性特性的理解 正常和正常心脏的机械特性(弹性和顺应性) 心脏疾病。我们的目标是为一系列问题提供明确的答案 在提案文本中提出明确的问题，从而 为提高超声诊断能力提供依据。

The ultimate objective of the proposed research is to elucidate the physical principles underlying the use of ultrasound fore the definitive quantification of acoustic properties of heart muscle needed for optimal diagnosis and assessment of function. In clinical echocardiography, scans are made with the direction of propagation of ultrasound at varying angles relative to the local fiber orientation of the myocardium and throughout the contraction-relaxation cycle. We have demonstrated that the magnitudes of backscatter and attenuation vary substantially with the angle of insonification relative to the arrangement of myofibers in the ventricular walls. Anisotropy is responsible for the drop out of the lateral and septal wall echoes in parasternal short-axis echocardiographic views and is especially pertinent for quantitative tissue characterization which has as its goal assessment of the properties of the tissue itself, as opposed to assessment of dimensions or motion. We propose to continue and extend our systematic investigations of the extent of angular variation of the ultrasonic properties of the heart and their relationship to conventional echocardiography, automatic echocardiographic detection of tissue-blood interfaces, myocardial tissue characterization, and ultimately to ultrasonic assessment of myocardial elastic properties. Research during the current grant period has focused on anisotropic properties averaged over the entire thickness of the ventricular wall. In this competitive renewal proposal, we outline studies designed to delineate the transmural variation of elastic properties that parallel significant transmural variations in the three-dimensional architecture of normal and diseased myocardium by measuring the transmural variations of the anisotropy of backscatter, attenuation, and velocity of myocardium and comparing with appropriate experimental and mathematical models. We further propose strategies for overcoming potential stumbling blocks arising from anisotropy for echocardiographic imaging, automatic detection of cardiac chamber dimensions, and myocardial tissue characterization. The proposed research is designed to lay the groundwork for exploiting the anisotropy of myocardial elastic properties to achieve improved understanding of cardiac mechanical properties (elasticity and compliance) in normal and diseases hearts. Our goal is to provide definitive answers to a series of explicit questions posed in the text of the proposal and thus to provide a basis for improving the diagnostic power of ultrasonics.