TISSUE STRAIN AND ELASTICITY THROUGH SPECKLE MOTION

通过散斑运动测量组织应变和弹性

• 批准号: 6347364
• 负责人: MICHEL BERTRAND
• 金额: $ 27.98万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCI CTR HOUSTON
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-08-28 至 2001-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6347364
• 关键词: bioimaging /biomedical imaging; breast neoplasms; clinical research; computer simulation; diagnosis quality /standard; elastic tissue; elasticity; hardness; human data; human subject; image processing; mathematical model; model design /development; neoplasm /cancer diagnosis; phantom model; prostate neoplasms; ultrasonography; women's health

The long term objective of this research is to develop a method to infer and image tissue hardness using ultrasound. This method would bring new quantitative information about the condition of a tissue, similar to what palpation does qualitatively when sensing "hard" tumor of a muscle under contraction. It consists essentially in measuring the deformation induced through an external force, the deformation being large in a compliant (i.e. soft) material and smaller in a rigid (hard) one. As proposed here, tissue deformation is assessed by tracking the spatio- temporal changed induced by the compression force on the ultrasound speckle patterns. Technically, this application is for developing a model-based approach to compute the elasticity distribution (also called the elastogram) using ultrasound speckle replacement data. First, it is proposed to study a direct elasticity problem; here the aim is to provide an analytical framework and a computer model of image formation for speckle correlation and motion, assuming an elastic scattering medium subjected to deformations. From a theoretical point of view, this will serve to better understand the complex relationship between the spatio-temporal changes in ultrasound signals and underlying tissue motion. From a practical standpoint, this will serve to develop and test tissue motion estimators based either on speckle correlation measurement or on optical flow. Tissue motion estimation is the first step in solving the inverse elasticity problem which can be stated as: determining the spatial distribution of elasticity that could best reproduce the estimated tissue motion under constraints provided by the elasticity equations and boundary conditions. It is proposed to develop an iterative procedure to seek the optimal elastogram, i.e. a non linear minimization method based on the image formation model, the optical flow equation and the elasticity equations. It is also proposed to study the feasibility of in vivo elastography of the prostate. This research on a method to infer tissue hardness will be conducted using computer modeling, and the method will be validated on a phantom model. The feasibility of in vivo prostate elastography will be examined through a subcontract project conducted in Lyons, France (Dr. jean Yves Chapelon) using ultrasound signals currently being acquired in a separate study investigating hyperthermia induced by high intensity focused ultrasound.

本研究的长期目标是发展一种利用超声推断和成像组织硬度的方法。这种方法将带来关于组织状况的新的定量信息，类似于触诊在感觉肌肉收缩的“硬”肿瘤时所做的定性。它主要包括测量由外力引起的变形，在柔性（即软）材料中变形大，在刚性（硬）材料中变形小。正如本文所提出的，组织变形是通过跟踪压缩力在超声散斑图上引起的时空变化来评估的。从技术上讲，这个应用程序是为了开发一种基于模型的方法来计算弹性分布（也称为弹性图），使用超声波散斑替换数据。首先，提出研究直接弹性问题；这里的目的是为散斑相关和运动提供一个分析框架和图像形成的计算机模型，假设弹性散射介质受到变形。从理论的角度来看，这将有助于更好地理解超声信号的时空变化与潜在组织运动之间的复杂关系。从实际的角度来看，这将有助于开发和测试基于散斑相关测量或光流的组织运动估计器。组织运动估计是解决反弹性问题的第一步，它可以表述为：在弹性方程和边界条件的约束下，确定最能再现估计的组织运动的弹性空间分布。提出了一种求最优弹性图的迭代过程，即基于成像模型、光流方程和弹性方程的非线性最小化方法。研究前列腺体内弹性成像的可行性。本研究将采用计算机建模的方法来推断组织硬度，并在一个幻影模型上对该方法进行验证。体内前列腺弹性成像的可行性将通过在法国里昂进行的一个分包项目（jean Yves Chapelon博士）进行检验，该项目使用的是目前在另一项研究中获得的超声信号，该研究是由高强度聚焦超声引起的热疗。