基于脑磁图对癫痫病灶与镜像源的仿真计算

Parameter estimation of epileptic focus and its mirror with magnetoencephalogram by computer simulation

脑磁技术的一个重要应用是对癫痫病灶的定位 .有一类癫痫发作时 ,在脑内与病灶的对称位置处 ,出现时域上有一个延迟的镜像源 ,此时区分病灶与镜像源就变得非常重要 .通过分析时域 -空域脑磁数据矩阵的秩 ,可以获得不同时间段里脑内电活动源的数目 .进而在不同时刻选用相应的源数目 ,并利用最优化方法 ,即可反演出脑内电活动的动态参数 ,从而完成癫痫病灶及镜像源的区分与定位 ,仿真计算表明该方法是可行的 .

One important clinical application of magnetoencephalography is for localizing focal epileptic foci. For one kind of epilepsy, there are two epileptic foci in bomotopic areas of the hemispheres. One is real focus; the other is called epileptic mirror becouse the discharges occur later than the real one. So it is important to distinguish the real focus and its mirror before surgical operation. Generally a focal epileptic focus can be modeled as a current dipole, so that parameter estimation method for current dipoles can be used in this clinical diagnosis. The number of current dipoles in a human brain during a certain period can be obtained by estimating the rank of the spatio\|temporal MEG data matrix. Once the dipole number is obtained, the dynamical parameters of the dipoles can be determined by using optimization algorithms. With the use of this method the real epileptic focus and its mirror can be distinguished and localized. Computer simulation confirmed the effectiveness of the above method.