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理解创伤性脑损伤（TBI）并开发预防方法，但目前的计算机模型尚未完全验证，主要是由于缺乏直接测量脑变形。这种缺乏实验证实的情况是取得进展的一个重要障碍。我们已经开发和应用MR标签和MR弹性成像（MRE）方法来测量二维大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，并将结果转换为计算机模型。我们将获得关于人类受试者大脑变形的高分辨率3D实验数据，以解决TBI生物力学的基本问题，并加速开发经过验证的可靠计算机模型。该项目是由验证模拟的需要驱动的，它将澄清 大脑关键特征的作用。提出了三个具体目标：目标1：测量大脑和颅骨之间的3D相对运动，并估计在轻微的线性和角向头部加速度过程中，活的人和尸体大脑中的3D应变场。目的2：表征3D波传播并评估残余应力、纤维拉伸、纤维-基质相互作用以及 界面上的波传播在活的人类和离体羊脑。目标3：将3D位移和应变场与大脑生物力学计算机模型的预测进行定量比较，并评估解剖结构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：在大脑对颅骨加速度的反应中，系留和支持结构（血管和脑膜）的作用是什么？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能力，并且我们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TBI的易感性。该项目的主要贡献将是用于TBI计算机模型验证的新数据和分析技术，这是由项目团队在3D大脑运动成像，自动图像分割和配准以及大脑和颅骨数学建模方面的技术开发实现的。计算机建模与MR标记和MR弹性成像实验数据采集的直接集成将加速可靠、准确模拟的发展。在项目结束时，我们将：（1）根据我们的数据验证计算机模型，这将允许可视化和定量预测大脑在选定的加速/冲击过程中所经历的3D应变;（2）其他人可以公开获得的数据，以建立和验证新的TBI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.