Image Guided Constitutive Modeling of the Brain Tissue

描述（由申请人提供）： 我们的最终目标是开发一种图像引导的机械计算工具，用于神经外科治疗和手术。该工具将允许在任何类型的机械激励期间预测大脑变形。为了实现这一最终目标，我们的长期目标将是发展可靠的本构模型的力学行为的在体人脑组织。我们建议通过对脑室造口术-颅内压升高（ICP）的缓解-大脑反应的整体MR或CT图像来定义体内脑组织的机械特性。 使用最先进的3D图像分析，这些图像可以转换为位移和应变场。利用脑响应的逆分析，可以开发脑组织的本构模型。这种逆分析代表了一个具有挑战性的耦合成像-力学问题，我们将其称为图像引导本构建模（IGCM）。IGCM是一个复杂的迭代过程，适应一个选定的本构模型，以模仿变形组织的行为。拟议的试点研究的目标是在受控环境中开发和测试图像引导本构建模的概念：在植入“肿瘤”的脑模型上，尽可能模拟体内脑几何形状，机械性能和边界条件。为达致这个目标，拟议的研究将达致下列目标： 目标1：使用硅凝胶铸造的人脑左半球体模对肿瘤脑行为进行物理建模，并进行“脑室造口术”和“压痕”测试。 目的2：基于图像从脑体模变形前后的CT图像推导应变场。 目标3：应变场的逆有限元分析和新的材料相容框架-超塑性本构模型的推导。 目标4：在将“健康”组织和“肿瘤”从体模中移除后，根据从“健康”组织和“肿瘤”中提取的样本的元素测试数据验证数值模型。

DESCRIPTION (provided by applicant): Our ultimate goal is a development of an image guided mechanical computational tool for applications in therapy and surgery with neurosurgery being our initial focus. The tool will allow for prediction of the brain deformation during any kind of mechanical excitation. Towards this ultimate goal, our long-term objective will be a development of reliable constitutive models of the mechanical behavior of the in-vivo human brain tissue. We propose to define the mechanical properties of the brain tissue in-vivo by taking the global MR or CT images of a brain response to ventriculostomy - the relief of the elevated intracranial pressure (ICP). Using state-of-the-art 3D image analysis, these images can be translated into displacement and strain fields. Using inverse analysis of the brain response, the constitutive models of the brain tissue can be developed. This inverse analysis represents a challenging coupled imaging-mechanical problem, which we will term Image Guided Constitutive Modeling (IGCM). The IGCM is a complex iterative process of adapting a chosen constitutive model to mimic the deformed tissue behavior. The goal of the proposed pilot research is to develop and test the concepts of the Image Guided Constitutive Modeling in the controlled environment: on the brain phantoms with implanted "tumors", with the best possible simulation of the in-vivo brain geometry, mechanical properties and boundary conditions. Towards this goal, the following set of aims will be achieved in the proposed research: AIM 1: Physical modeling of the behavior of brain with tumor using phantom of the left hemisphere of human brain cast from silicon gel and subjected to "ventriculostomy" and "indentation" tests. AIM 2: Image based derivation of the strain fields from pre- and post-deformation CT images of the brain phantom. AIM 3: Inverse finite element analysis of the strain fields and derivation of constitutive models within the novel thermodynamically consistent framework - Hyperplasticity. AIM 4: Verification of the numerical models against the data from the element tests on the samples extracted from the "healthy" issue and the "tumor, after the latter is removed from the phantom.