Observation of direction-dependent mechanical properties in the human brain with multi-excitation MR elastography
Observation of direction-dependent mechanical properties in the human brain with multi-excitation MR elastography
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DOI：
10.1016/j.jmbbm.2016.03.005
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发表时间：
2016-06-01
影响因子：
3.9
通讯作者：
Johnson, Curtis L.
中科院分区：
文献类型：
--
作者：
Anderson, Aaron T.;Van Houten, Elijah E. W.;Johnson, Curtis L.
磁共振弹性成像（MRE）在无创捕捉由神经退行性疾病引起的人脑机械特性变化方面显示出了希望。MRE包括震动大脑产生剪切波，用核磁共振成像成像这些波，并解决一个反问题来确定机械特性。尽管已知脑组织具有各向异性的性质，但脑磁共振反问题是基于各向同性力学模型的。在本研究中，通过使用多个激励方向在大脑中产生不同的波形，以表征各向异性组织力学对各向同性反演方法的潜在影响。两个独特位移场的各向同性反转导致在高度排列的白质区域局部变化的机械属性图。对胼胝体、辐射冠和上纵束这三个高度有序的白质束的研究显示，在不同的兴奋状态下，估计的性质差异高达33%。利用扩散张量成像技术识别纤维束的主导方向，揭示了估计的各向同性与剪切不对称性之间的关系。本研究对未来人类大脑白质束各向同性和各向异性的核磁共振研究具有指导意义。(C) 2016 Elsevier Ltd.版权所有。
Magnetic resonance elastography (MRE) has shown promise in noninvasively capturing changes in mechanical properties of the human brain caused by neurodegenerative conditions. MRE involves vibrating the brain to generate shear waves, imaging those waves with MRI, and solving an inverse problem to determine mechanical properties. Despite the known anisotropic nature of brain tissue, the inverse problem in brain MRE is based on an isotropic mechanical model. In this study, distinct wave patterns are generated in the brain through the use of multiple excitation directions in order to characterize the potential impact of anisotropic tissue mechanics on isotropic inversion methods. Isotropic inversions of two unique displacement fields result in mechanical property maps that vary locally in areas of highly aligned white matter. Investigation of the corpus callosum, corona radiata, and superior longitudinal fasciculus, three highly ordered white matter tracts, revealed differences in estimated properties between excitations of up to 33%. Using diffusion tensor imaging to identify dominant fiber orientation of bundles, relationships between estimated isotropic properties and shear asymmetry are revealed. This study has implications for future isotropic and anisotropic MRE studies of white matter tracts in the human brain. (C) 2016 Elsevier Ltd. All rights reserved.