基于扩散张量成像利用一阶有限元方法计算脑白质各向异性电导率对脑电位分布的影响

目的 研究脑白质各向异性电导率对头皮电位分布的影响.方法 把由扩散张量成像得到的水分子扩散张量采用体积约束规则计算出白质组织的电导率张量,并根据成像的空间信息建立了包括头皮、颅骨、灰质、脑脊液及白质5种组织的真实头的有限元模型.基于此模型,推导了各向异性电导率脑电正问题的一阶有限元数值算法.最后,采用电流偶极子模型计算头皮电位分布.结果 脑白质各向异性电导率对头皮电位分布有一定的影响,径切比越大,影响越大;左右分布偶极子比上下分布的影响要大.结论 脑电研究中,白质电导率的各向异性为一不可忽略的因素.

Effects of Brain White Matter Anisotropic Conductivity on Distribution of EEG Calculated with Finite Element Method Based on Diffusion Tensor Image (DTI) of Nuclear Magnetic Resonance

Objective To study the influence of white matter anisotropic conductivity on scalp electric potential distribution. Methods According to the volume constraint water diffusion tensor was converted to conductivity tensor, and the five-layer (white matter, grey matter, CSF, skull, scalp) finite element model (FEM) was constructed based on the DTI data. Based on this model first-order FEM algorithm was implemented. And the scalp electric potential distribution was calculated by using current dipole modal. Results Anisotropic conductivity of white matter has influence in EEG problem, and more influence when the ratio of radius and tangential of volume constraint is greater. The right-left dipoles have more influence than superior-inferior ones. Conclusion In the study of EEG, the anisotropic conductivity of brain tissue cannot be neglected.