Spectrally optimized, Spatially resolved Poro and Viscoelastic Brain MRE

描述（由申请人提供）：我们已经建立了一种创新的脑磁共振弹性成像（MRE）方法，该方法基于内源性低频（~1Hz）运动的编码，这些运动是由血液脉动通过脑血管系统产生的，用孔隙弹性力学模型重建，以产生三维（3D），空间分辨率的力学和流体动力学特性图像。我们的多孔弹性MRE （pMRE）方法已经在幽灵，动物和人类中产生了有希望的初步数据。与此同时，我们也在基于外部高频（50- 100Hz）驱动的粘弹性MRE （vMRE）方法上取得了长足的进步，并且我们在幻影、动物和人类中进行的最新vMRE研究的初步数据也非常令人印象深刻，因为可以获得空间分辨的力学特性信息。事实上，我们有证据表明，vMRE和pMRE是互补的，即vMRE是外部驱动的高频下的首选方法，在这种情况下，脑实质的粘性阻尼效应更占主导地位，而pMRE是内部驱动的低频下的最佳选择，在这种情况下，流体动力效应变得更重要。我们在这个项目中的总体目标是统一和优化我们的pMRE和vMRE方法，以便在一系列幻影和动物模型系统的感兴趣的频谱（~1-100Hz）上对它们进行评估，这些系统将确定它们提供优越，可比和/或互补的图像和数据的条件。具体而言，我们将(1)开发一个统一的框架和平台，通过该框架和平台，我们将推进和优化我们的pMRE和vMRE图像重建方法；(2)使用驱动和幻影系统在感兴趣的频率范围内进行比较评估；(3)在三个具有可控参数和实验条件的大型动物模型中完成实验，在体内进行比较评估。已有证据支持脑磁共振成像在多种神经系统疾病的临床识别和管理方面的潜力。我们假设大脑MRE有更多的东西可以提供——具体来说，3D、光谱优化、空间分辨的组织力学和流体力学特性图应该是标准，而不是迄今为止大部分报道的整个/区域大脑力学特性的平均值。外部和内在脑驱动都有优点，pMRE和vMRE也是如此；因此，需要集中和持续的努力，在可用的频率范围内优化、评价和比较这些方法，以确定在选定的和感兴趣的普遍条件下的选择方法。

DESCRIPTION (provided by applicant): We have established an innovative approach to brain magnetic resonance elastography (MRE) based on encoding of endogenous low frequency (~1Hz) motion resulting from blood pulsation through the cerebrovascular system that is reconstructed with a poroelastic mechanical model to produce three- dimensional (3D), spatially-resolved mechanical and hydrodynamical property images. Our poroelastic MRE (pMRE) methods have produced promising preliminary data in phantoms, animals, and humans. In parallel, we have advanced substantially our viscoelastic MRE (vMRE) methods based on external high frequency (50- 100Hz) actuation, and preliminary data from our latest vMRE studies in phantoms, animals and humans are also very impressive because of the spatially-resolved mechanical property information that can be obtained. Indeed, we have evidence to suggest that vMRE and pMRE are complementary - namely that vMRE is the method of choice at externally-actuated high frequencies where the viscous damping effects of brain parenchyma are more dominant, whereas pMRE is the best choice at intrinsically-actuated low frequencies where the hydrodynamic fluid effects become more important. Our overall objective in this project is to unify and optimize our pMRE and vMRE methods in order to evaluate them across the frequency spectrum of interest (~1-100Hz) in a series of phantom and animal model systems which will identify the conditions under which they provide superior, comparable and/or complementary images and data. Specifically, we will (1) develop a unified framework and platform through which we will advance and optimize our pMRE and vMRE image reconstruction methods, (2) use actuation and phantom systems for comparative evaluations across the frequency range of interest, and (3) complete experiments in three large animal models with controllable parameters and experimental conditions under which comparative evaluations will occur in vivo. Evidence already exists to support the potential of brain MRE to inform clinical identification and management of multiple neurological disorders. We hypothesize that brain MRE has much more to offer - specifically, that 3D, spectrally-optimized, spatially-resolved maps of tissue mechanical and hydrodynamical properties should be the standard - not the whole/regional brain mechanical property averages that have largely been reported to date. External and intrinsic brain actuation both have merit, as do pMRE and vMRE; hence, a focused and sustained effort to optimize, evaluate and compare these approaches across the available frequency range is needed to identify the methods of choice under selected and prevailing conditions of interest.