PDF(Pubmed)
Abstract：
Diffusion tensor magnetic resonance electrical impedance tomography (DT-MREIT) and electrodeless conductivity tensor imaging (CTI) are two emerging modalities that can quantify low-frequency tissue anisotropic conductivity properties by assuming similar properties underlie ionic mobility and water diffusion. While both methods have potential applications to estimating neuro-modulation fields or formulating forward models used for electrical source imaging, a direct comparison of the two modalities has not yet been performed in-vitro or in-vivo. Therefore, the aim of this study was to test the equivalence of these two modalities. We scanned a tissue phantom and the head of human subject using DT-MREIT and CTI protocols and reconstructed conductivity tensor and effective low frequency conductivities. We found both gray and white matter conductivities recovered by each technique were equivalent within 0.05 S/m. Both DT-MREIT and CTI require multiple processing steps, and we further assess the effects of each factor on reconstructions and evaluate the extent to which different measurement mechanisms potentially cause discrepancies between the two methods. Finally, we discuss the implications for spectral models of measuring conductivity using these techniques. The study further establishes the credibility of CTI as an electrodeless non-invasive method of measuring low frequency conductivity properties.
摘要：
扩散张量磁共振电阻抗断层扫描（DT-MREIT）和无电极电导率张量成像（CTI）是两种新兴的模式，可以通过假设离子迁移率和水扩散背后的相似特性来量化低频组织各向异性电导率特性。虽然这两种方法在估计神经调制场或制定用于电源成像的正向模型方面都有潜在的应用。两种模式的直接比较尚未在体外或体内进行。因此,这项研究的目的是测试这两种模式的等效性。我们使用DT-MREIT和CTI协议扫描了组织体模和人类受试者的头部，并重建了电导率张量和有效的低频电导率。我们发现通过每种技术恢复的灰质和白质电导率在0.05S/m内相等。DT-MREIT和CTI都需要多个处理步骤，我们进一步评估了每个因素对重建的影响，并评估了不同的测量机制可能导致两种方法之间的差异的程度。最后,我们讨论了使用这些技术测量电导率的光谱模型的含义。该研究进一步确立了CTI作为测量低频电导率特性的无电极非侵入性方法的可信度。
