基于头部组织不同电导率特性的阻抗成像正问题仿真研究

Forward problem based on the conductivity characteristics of head tissues： simulation research

目的通过建立5层有限元真实头模型，研究了各层组织非均质和颅骨、脑白质各向异性电特性对电阻抗成像问题中电磁场分布的影响。方法对头部各组织建立4种电导率分布模型：均质分布、非均质分布以及颅骨和脑白质各向异性电导率模型；通过正问题数值求解得到不同模型下的磁场分布和电场分布，并通过定量的统计分析研究非均质和各向异性电导率特性对电磁场分布的影响。结果表明电磁场分布对头部组织非均质和各向异性电导率分布是敏感的。结论此研究为基于核磁共振电阻抗成像技术对头部组织各向异性和非均质电导率进行重构奠定了一定的理论研究基础。

Objectives This paper is focused on the investigation of effects of inhomogeneous head tissues and anisotropic skull as well as white matter conductivity distribution on magnetic and electric field distribution of electric impedance tomography （EIT） and magnetic resonance electrical impedance tomography （MREIT） based on the five-layer FEM head modeling. Methods Four different characteristics head models were set： homogeneous distribution, inhomogeneous distribution, anisotropic skull and white matter distribution. Electric and magnetic field distribution were obtained by the performance of numeric solving of the forward problem, and the effects of inhomogeneous conductivity and anisotropic conductivity on the distribution were studied by applying the quantitative statistical analysis. Results The present results showed that inhomogeneous and anisotropic characteristics can significantly alter the electric field and current density distributions then the magnetic field distribution induced in the brain. Conclusion The conclusion provides theoretical basis for the application of MREIT in the reconstruction of inhomogeneous and anisotropic conductivity of head tissues.