Brain-mimicking phantom for biomechanical validation of motion sensitive MR imaging techniques
Brain-mimicking phantom for biomechanical validation of motion sensitive MR imaging techniques
复制标题
用于运动敏感 MR 成像技术生物力学验证的仿脑模型
DOI：
10.1016/j.jmbbm.2021.104680
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发表时间：
2021
影响因子：
3.9
通讯作者：
Ueda, J.
中科院分区：
文献类型：
--
作者：
Ozkaya, E.;Triolo, E.R.;Rezayaraghi, F.;Abderezaei, J.;Meinhold, W.;Hong, K.;Alipour, A.;Kennedy, P.;Fleysher, L.;Ueda, J.
运动敏感MR成像技术允许通过使用不同的激励方案对生物组织进行非侵入性评估，包括由心脏脉动或呼吸引起的生理/内在运动以及由外部致动器引起的振动。通过这些成像技术提取的机械生物标志物已被证明对各种神经系统疾病和病症具有诊断价值。放大MRI（aMRI）是一种心脏门控成像技术，可以帮助跟踪和量化大脑的低频固有运动。至于高频激励，脑组织的机械响应可以通过施加外部高频激励结合称为磁共振弹性成像（MRE）的运动敏感MR成像序列来测量。由于脑力学的频率依赖性行为，需要开发能够模拟脑的宽带机械响应的脑体模模型，以验证运动敏感的MR成像技术。在这里，我们设计了一种新的体模测试设置，使大脑模仿体模的低频和高频响应被捕获，允许aMRI和MRE成像技术被应用于同一体模模型。该装置结合了两种不同的振动源：用于aMRI的低频/固有运动（1 Hz）的气动致动器，以及用于MRE的高频致动（30-60 Hz）的压电致动器。我们的研究结果表明，在从30 Hz到60 Hz进行的MRE实验中，传播的剪切波在较高的驱动频率下衰减得更快，与文献中的结果一致。此外，致动器耦合对波振幅具有实质性影响，较弱的耦合导致较低振幅的波场图像，具体地在顶面剪切加载配置中示出。对于内在驱动，我们的结果表明，aMRI线性放大运动，对于可见和亚体素运动的实例，至少放大因子为9，通过在MR下改变气动驱动的功率水平（40%-80%功率）以及通过MRI扫描仪室外的视频分析进行验证。虽然这项研究使用了一个均匀的大脑模仿体模，我们的设置可以用来研究非均匀体模配置与生物界面的力学在未来。
Motion sensitive MR imaging techniques allow for the non-invasive evaluation of biological tissues by using different excitation schemes, including physiological/intrinsic motions caused by cardiac pulsation or respiration, and vibrations caused by an external actuator. The mechanical biomarkers extracted through these imaging techniques have been shown to hold diagnostic value for various neurological disorders and conditions. Amplified MRI (aMRI), a cardiac gated imaging technique, can help track and quantify low frequency intrinsic motion of the brain. As for high frequency actuation, the mechanical response of brain tissue can be measured by applying external high frequency actuation in combination with a motion sensitive MR imaging sequence called Magnetic Resonance Elastography (MRE). Due to the frequency-dependent behavior of brain mechanics, there is a need to develop brain phantom models that can mimic the broadband mechanical response of the brain in order to validate motion-sensitive MR imaging techniques. Here, we have designed a novel phantom test setup that enables both the low and high frequency responses of a brain-mimicking phantom to be captured, allowing for both aMRI and MRE imaging techniques to be applied on the same phantom model. This setup combines two different vibration sources: a pneumatic actuator, for low frequency/intrinsic motion (1 Hz) for use in aMRI, and a piezoelectric actuator for high frequency actuation (30–60 Hz) for use in MRE. Our results show that in MRE experiments performed from 30 Hz through 60 Hz, propagating shear waves attenuate faster at higher driving frequencies, consistent with results in the literature. Furthermore, actuator coupling has a substantial effect on wave amplitude, with weaker coupling causing lower amplitude wave field images, specifically shown in the top-surface shear loading configuration. For intrinsic actuation, our results indicate that aMRI linearly amplifies motion up to at least an amplification factor of 9 for instances of both visible and sub-voxel motion, validated by varying power levels of pneumatic actuation (40%–80% power) under MR, and through video analysis outside the MRI scanner room. While this investigation used a homogeneous brain-mimicking phantom, our setup can be used to study the mechanics of non-homogeneous phantom configurations with bio-interfaces in the future.