脑磁图研究的若干理论问题(上)——基本电磁学方程及脑磁正问题

Some basic theories on magnetoencephalographic research (Ⅰ)basic electromagnetic equations and magnetoence-phalographic forward problem solution

本文概述了脑磁技术的发展历程、现状及潜在的临床价值。详细阐述了脑磁研究中使用的基本电磁学理论 ,包括描述电磁规律最基本的麦克斯韦方程组 ,生物电磁研究中麦氏方程的准静态近似条件 ,介质分区域均匀时计算电场、磁场的 Geselowitz公式。在准静态近似条件下 ,讨论了原在电流密度 (Primary current density)与脑外磁场的线性关系。阐述了脑磁正问题中常用的球对称导体模型解及基于真实头模型的边界元方法解。

A brief overview is given of magnetoencephalography(MEG),including a brief history,present status and some potential clinical applications.Basic electromagnetic theories used on MEG studies are then explained in detail.These theories include Maxwell equations describing electromagnetic fields,the quasistatic approximation conditions of Maxwell equations on bioelectromagnetic studies,and Geselowitz formula used to compute electromagnetic fields in piecewise homogeneous conductor.In the quasistatic appximation,the linear relationship between primary current density and magnetic field on the surface of the head is explained.The forward problem solutions based on spherically symmetric conductor model and boundary element method used on real model solution are also discussed.