Viscoelastic properties of the ferret brain measured in vivo at multiple frequencies by magnetic resonance elastography.
Viscoelastic properties of the ferret brain measured in vivo at multiple frequencies by magnetic resonance elastography.
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DOI：
10.1016/j.jbiomech.2012.12.024
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发表时间：
2013-03-15
影响因子：
2.4
通讯作者：
Bayly PV
中科院分区：
文献类型：
--
作者：
Feng Y;Clayton EH;Chang Y;Okamoto RJ;Bayly PV
脑组织动态力学行为的表征对于理解和模拟创伤性脑损伤（TBI）的机制至关重要。机械性能的变化也可能反映出大脑因衰老或疾病而发生的变化。在这项研究中，我们使用磁共振弹性成像（MRE）来测量雪貂脑组织在体内的粘弹性。三维（3D）位移场采集过程中的波传播引起的颅骨在400 Hz，600 Hz和800 Hz的谐波激励。在位移场、应变场和位移场的旋度（不包含纵波的贡献）中，可以清楚地看到波长为毫米量级的剪切波。粘弹性参数（存储和损耗模量）动态剪切变形的灰色和白色的问题，这些激励频率估计。为了表征测量的再现性，在三个不同的日期对两只雪貂进行了研究。雪貂脑中白色物质的估计粘弹性通常与灰质相似，并且在动物和扫描日期之间一致。在两种组织类型中，G′从400 Hz时的约3 kPa增加到800 Hz时的7 kPa，G″从400 Hz时的约1 kPa增加到800 Hz时的2 kPa。雪貂脑中剪切波传播的这些测量值可用于脑生物力学的有限元模型的参数化和验证。
Characterization of the dynamic mechanical behavior of brain tissue is essential for understanding and simulating the mechanisms of traumatic brain injury (TBI). Changes in mechanical properties may also reflect changes in the brain due to aging or disease. In this study, we used magnetic resonance elastography (MRE) to measure the viscoelastic properties of ferret brain tissue in vivo. Three-dimensional (3D) displacement fields were acquired during wave propagation in the brain induced by harmonic excitation of the skull at 400 Hz, 600 Hz and 800 Hz. Shear waves with wavelengths on the order of millimeters were clearly visible in the displacement field, in strain fields, and in the curl of displacement field (which contains no contributions from longitudinal waves). Viscoelastic parameters (storage and loss moduli) governing dynamic shear deformation were estimated in gray and white matter for these excitation frequencies. To characterize the reproducibility of measurements, two ferrets were studied on three different dates each. Estimated viscoelastic properties of white matter in the ferret brain were generally similar to those of gray matter and consistent between animals and scan dates. In both tissue types G′ increased from approximately 3 kPa at 400 Hz to 7 kPa at 800 Hz and G″ increased from approximately 1 kPa at 400 Hz to 2 kPa at 800 Hz. These measurements of shear wave propagation in the ferret brain can be used to both parameterize and validate finite element models of brain biomechanics.