Measurement of the dynamic shear modulus of mouse brain tissue in vivo by magnetic resonance elastography
Measurement of the dynamic shear modulus of mouse brain tissue in vivo by magnetic resonance elastography
复制标题
DOI：
10.1115/1.2899575
复制
发表时间：
2008-04-01
影响因子：
1.7
通讯作者：
Bayly, Philip V.
中科院分区：
文献类型：
--
作者：
Atay, Stefan M.;Kroenke, Christopher D.;Bayly, Philip V.
本研究利用磁共振弹性成像技术对小鼠在体脑组织的动态剪切模量进行了测量。该技术允许可视化和测量由颅骨的横向振动激发的机械剪切波。三维位移的定量测量。通过在MR成像序列期间以相同频率施加振荡磁场梯度来获得1200 Hz的振动。小鼠大脑的相位图像中的对比度与位移成比例。为了获得剪切模量的估计值，将测得的位移场拟合到剪切波方程。对通过独立流变测试表征的凝胶和有限元模拟数据进行了程序验证。脑组织实际上是粘弹性和非线性的。目前的动态剪切模量的估计是严格相关的，只有在一个特定的频率小的振荡，但这些估计可以在高频率（因此高变形率），非侵入性地在整个大脑。这些数据补充了其他人在较慢的速率下获得的非线性粘弹性特性的测量，无论是离体还是侵入性的。
In this study, the magnetic resonance (MR) elastography technique was used to estimate the dynamic shear modulus of mouse brain tissue in vivo. The technique allows visualization and measurement of mechanical shear waves excited by lateral vibration of the skull. Quantitative measurements of displacement in three dimensions during. vibration at 1200 Hz were obtained by applying oscillatory magnetic field gradients at the same frequency during a MR imaging sequence. Contrast in the resulting phase images of the mouse brain is proportional to displacement. To obtain estimates of shear modulus, measured displacement fields were fitted to the shear wave equation. Validation of the, procedure was performed on gel characterized by independent rheometry tests and on data from finite element simulations. Brain tissue is, in reality, viscoelastic and nonlinear. The current estimates of dynamic shear modulus are strictly relevant only to small oscillations at a specific frequency; but these estimates may be obtained at high frequencies (and thus high deformation rates), noninvasively throughout the brain. These data complement measurements of nonlinear viscoelastic properties obtained by others at slower rates, either ex vivo or invasively.