Department of Biomedical Engineering, University of Delaware, Newark, DE 19716.
Department of Mechanical Engineering and Material Science, Washington University, St. Louis, MO 63130.
J Biomech Eng. 2020 Jul 1;142(7):0710051-9. doi: 10.1115/1.4046199.
Magnetic resonance elastography (MRE) has emerged as a sensitive imaging technique capable of providing a quantitative understanding of neural microstructural integrity. However, a reliable method for the quantification of the anisotropic mechanical properties of human white matter is currently lacking, despite the potential to illuminate the pathophysiology behind neurological disorders and traumatic brain injury. In this study, we examine the use of multiple excitations in MRE to generate wave displacement data sufficient for anisotropic inversion in white matter. We show the presence of multiple unique waves from each excitation which we combine to solve for parameters of an incompressible, transversely isotropic (ITI) material: shear modulus, μ, shear anisotropy, ϕ, and tensile anisotropy, ζ. We calculate these anisotropic parameters in the corpus callosum body and find the mean values as μ = 3.78 kPa, ϕ = 0.151, and ζ = 0.099 (at 50 Hz vibration frequency). This study demonstrates that multi-excitation MRE provides displacement data sufficient for the evaluation of the anisotropic properties of white matter.
磁共振弹性成像（MRE）已成为一种敏感的成像技术，能够提供对神经微观结构完整性的定量理解。然而，尽管有可能阐明神经障碍和创伤性脑损伤背后的病理生理学，但目前仍然缺乏一种可靠的方法来量化人类白质的各向异性力学性质。在这项研究中，我们研究了在 MRE 中使用多次激发来产生足以进行白质各向异性反演的波位移数据。我们展示了来自每个激发的多个独特波的存在，我们将这些波组合起来以求解不可压缩、横向各向同性（ITI）材料的参数：剪切模量 μ、剪切各向异性 ϕ 和拉伸各向异性 ζ。我们在胼胝体体部计算这些各向异性参数，发现平均值为 μ=3.78kPa、ϕ=0.151 和 ζ=0.099（在 50Hz 振动频率下）。这项研究表明，多激发 MRE 提供了足以评估白质各向异性性质的位移数据。
