Can high-field MREIT be used to directly detect neural activity? Theoretical considerations.
Can high-field MREIT be used to directly detect neural activity? Theoretical considerations.
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DOI：
10.1016/j.neuroimage.2010.04.005
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发表时间：
2010-08-01
期刊：
影响因子：
5.7
通讯作者：
Woo, E. J.
中科院分区：
文献类型：
--
作者：
Sadleir, R. J.;Grant, S. C.;Woo, E. J.
我们试图确定直接研究神经组织活动的可行性，通过分析当涓流施加到含有活性或静息神经组织的浴中时发生的MRI信号中的微分相移。我们开发了一个有限元bidomain模型的失智症腹神经节，以估计这种对比机制的敏感性，发生在回鳃反射过程中的细胞膜电导的变化。我们使用我们的模型来确定电流密度和磁势分布包含一个孤立的神经节的样品室中，当它被照亮与MR成像序列同步注入电流，并预测MRI相位图像的变化。本研究为磁共振电阻抗断层扫描（MREIT）成像神经功能的尝试提供了基础。我们发现，候选17.6 T MRI系统中的相位噪声应足够低，以检测分辨率约为1 mm3的活动和静息膜状态之间的相位信号差异。我们进一步描绘了广泛的依赖性的信噪比的活动频率，当前的应用时间和活性组织分数，并概述了策略，可用于降低相位噪声低于目前在传统的MREIT技术中观察到的。我们还提出了使用MREIT作为研究神经调节的替代手段的想法。
We sought to determine the feasibility of directly studying neural tissue activity by analysis of differential phase shifts in MRI signals that occurred when trickle currents were applied to a bath containing active or resting neural tissue. We developed a finite element bidomain model of an aplysia abdominal ganglion in order to estimate the sensitivity of this contrast mechanism to changes in cell membrane conductance occurring during a gill-withdrawal reflex. We used our model to determine both current density and magnetic potential distributions within a sample chamber containing an isolated ganglion when it was illuminated with current injected synchronously with the MR imaging sequence, and predicted the resulting changes in MRI phase images. This study provides the groundwork for attempts to image neural function using Magnetic Resonance Electrical Impedance Tomography (MREIT). We found that phase noise in a candidate 17.6 T MRI system should be sufficiently low to detect phase signal differences between active and resting membrane states at resolutions around 1 mm3. We further delineate the broad dependencies of signal to noise ratio on activity frequency, current application time and active tissue fractions, and outline strategies that can be used to lower phase noise below that presently observed in conventional MREIT techniques. We also propose the idea of using MREIT as an alternative means of studying neuromodulation.
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