IN VIVO MEASUREMENT OF BRAIN BIOMECHANICS

描述(由申请人提供)： 项目摘要：需要脑生物力学的计算机模型来了解创伤性脑损伤(TBI)并开发预防方法，但目前的计算机模型尚未得到充分验证，这主要是由于缺乏对脑变形的直接测量。这种缺乏实验证实的情况是取得进展的重要障碍。我们已经开发和应用了磁共振标记和磁共振弹性成像(MRE)方法来测量2D脑运动和大脑的机械特性。在这个更新项目中，我们将把我们的方法扩展到3D，并将结果转换到计算机模型中。我们将获得人体脑变形的高分辨率3D实验数据，以解决脑外伤生物力学的基本问题，并加速开发经过验证的、可靠的计算机模型。该项目是由验证模拟的需求驱动的，它将澄清 大脑关键功能的作用。提出了三个具体的目标：目标1：测量脑和颅骨之间的三维相对运动，并估计活体和身体头部在温和的线和角加速过程中的三维应变场。目标2：描述3D波的传播特性，并评估残余应力、纤维拉伸、纤维-基质相互作用以及 活体人和体外羊脑中波传播的界面。目的3：将三维位移场和应变场与脑生物力学计算机模型的预测进行定量比较，并评估解剖和材料特性变化的重要性。在目标1中，我们将解决这个问题：系留和支持结构(血管和脑膜)在大脑对头骨加速的反应中扮演什么角色？在目标2中，我们询问这些结构以及残余应力和各向异性如何影响剪切波在大脑中的传播。在目标3中，我们将直接测试模拟预测大脑运动的效果，并将使用模拟来询问解剖结构的个体差异如何影响大脑生物力学和对脑外伤的易感性。该项目的主要贡献将是新的数据和分析技术，用于验证脑损伤的计算机模型，这得益于项目组在3D脑运动成像、自动图像分割和配准以及大脑和头骨的数学建模方面的技术开发。计算机建模与从MR标记和MR弹性成像获取实验数据的直接集成将加速可靠、准确的模拟的发展。在项目结束时，我们将拥有：(1)根据我们的数据进行验证的计算机模型，这些模型将允许可视化和定量预测大脑在选定的加速/撞击过程中经历的3D应变；(2)公开的数据，供其他人建立和验证新的脑损伤计算机模型。

DESCRIPTION (provided by applicant): PROJECT ABSTRACT: Computer models of brain biomechanics are needed to understand traumatic brain injury (TBI) and develop methods for prevention, but current computer models have not been fully validated, primarily due to the paucity of direct measurements of brain deformation. This lack of experimental confirmation represents an important barrier to progress. We have developed and applied MR tagging and MR elastography (MRE) methods to measure 2D brain motion and mechanical properties of the brain. In this renewal project we will extend our methods to 3D, and transition the results into computer models. We will acquire high-resolution 3D experimental data on brain deformation in human subjects to address basic questions on the biomechanics of TBI and to accelerate development of validated, reliable computer models. The project is driven by the need to validate simulations, and it will clarify the roles of key features of the brain. Three specific aims are proposed: Aim 1: Measure 3D relative motion between the brain and skull, and estimate 3D strain fields in live human and cadaver brains, during mild linear and angular head acceleration. Aim 2: Characterize 3D wave propagation and assess the effects of residual stress, fiber stretch, fiber-matrix interaction, and interfaces on wave propagation in the live human and ex vivo ovine brain. Aim 3: Compare 3D displacement and strain fields quantitatively to the predictions of a computer model of brain biomechanics, and assess the importance of variations in anatomy and material properties. In Aim 1 we will address the question: What are the roles of tethering and supporting structures (vessels and meninges) in the brain's response to skull acceleration? In Aim 2, we ask how these structures, as well as residual stress and anisotropy, affect shear wave propagation in the brain. In Aim 3, we will test directly how well simulations can predict brain motion, and we will use simulation to ask how individual variations in anatomy affect brain biomechanics and susceptibility to TBI. Key contributions of this project will be new data and analysis techniques for validation of computer models of TBI, enabled by the project team's technology developments in imaging of 3D brain motion, automated image segmentation and registration, and mathematical modeling of the brain and skull. The direct integration of computer modeling with acquisition of experimental data from MR tagging and MR elastography will accelerate development of reliable, accurate simulations. At the end of the project we will have: (1) computer models validated against our data that will allow visualization and quantitative prediction of the 3D strain experienced by the brain during selected acceleration/impacts; (2) publicly available data for others to build and validate new computer models of TBI.