Advanced Magnetic Resonance Elastography

描述(申请人提供)：磁共振弹性成像(MRE)是一种新兴的成像方式，旨在恢复组织机械特性的高分辨率地图。虽然这项技术在过去几年中取得了长足的进步，目前正在研究一些有前景的临床应用，但迄今为止产生的几乎所有结果都是基于组织是线性弹性的假设。然而，人们普遍认为，许多组织并不是作为各向同性的线弹性介质来响应的，而是表现出更复杂的力学行为。具体地说，它们可以用粘弹性、各向异性和非线性力学性质来更准确地表示。因此，如果这项技术要充分发挥其作为辅助诊断决策的潜力，那么扩展MRE方法以考虑这些更完整和更准确的力学特性特征似乎是至关重要的。拟议项目的总体目标是开发、验证和评估MRE方法，以根据组织对MRE过程中施加的刺激的机械响应来成像与组织作为粘弹性、各向异性或非线性介质的传统模型描述相关联的力学特性参数。该项目的具体目标是(1)开发在具有目标行为的模体中观察这些复杂机械效应所需的MR数据采集技术，(2)开发用于将MR位移数据转换为表征所使用的模体材料的力学性质估计的算法，以及(3)通过一系列模拟和模体实验来验证这些进展，所述一系列模拟和模体实验(A)确定力学性质估计过程的准确性、稳定性和唯一性，(B)优化模型复杂性和模型效率/稳定性之间的权衡，所述模型复杂性准确地表征运动(和机械性质)和当算法应用于活体数据时提供稳健性，以及(C)当介质表现出更复杂的力学性质时，确定由线弹性假设引起的剪切模量值估计误差的大小。

DESCRIPTION (provided by applicant): Magnetic Resonance Elastography (MRE) is an emerging imaging modality which seeks to recover high resolution maps of tissue mechanical properties. While the technique has been advanced considerably over the last several years and a number of promising clinical applications are now being investigated, almost all of the results produced to date have been based on the assumption that tissue is linearly elastic. However, it is generally accepted that many tissues do not respond as an isotropic linearly-elastic medium but rather exhibit more complex mechanical behaviors. Specifically, they can be more accurately represented by viscoelastic, anisotropic and nonlinear mechanical properties. As a result it seems critical to extend MRE methodology to account for these more complete and accurate mechanical property characterizations if the technique is to realize its full potential as an aid to diagnostic decision-making. The overall goal of the proposed project is to develop, validate and evaluate MRE methods for imaging the mechanical property parameters associated with conventional model descriptions of tissue as either a viscoelastic, an anisotropic or a nonlinear medium in terms of its mechanical response to the stimulus applied during MRE procedures. The specific aims of the project are to (1) Develop the MR data acquisition techniques required to observe these complex mechanical effects in phantoms that possess the targeted behaviors, (2) Develop the algorithms for converting the MR displacement data into mechanical property estimates which characterize the phantom materials used, and (3) Validate these developments through a series of simulation and phantom experiments which (a) determine the accuracy, stability and uniqueness of the mechanical property estimation process, (b) optimize the trade-off between model complexity which accurately characterizes the motion (and mechanical properties) and model efficiency/stability which provides robustness when algorithms are applied to in vivo data, and (c) identify the magnitude of the inaccuracies in shear modulus estimation incurred by assumptions of linear elasticity when the medium exhibits more complex mechanical properties.