Ollikainen J O, Vauhkonen M, Karjalainen P A, Kaipio J P
Department of Applied Physics, University of Kuopio, Finland.
Med Eng Phys. 1999 Apr;21(3):143-54. doi: 10.1016/s1350-4533(99)00038-7.
The accuracy of the head model affects the solutions of the EEG inverse problems. If a simple three-sphere model and standard conductivity values for brain, skull and scalp regions are used, significant errors may occur in the dipole localisation. One of the most sensitive head model parameters is the conductivity of the skull. A realistic three-dimensional finite-element model provides a method to study the effect of inhomogeneities of the skull on the solutions of EEG inverse problems. In this paper the effect of a local skull conductivity inhomogeneity on source estimation accuracy is analyzed by computer simulations for different numbers of electrodes. It is shown that if the inhomogeneity of the skull conductivity is not taken into account, localisation errors of approximately 1 cm can be encountered in the equivalent current dipole estimation. This modelling error introduces a bias to the solution which cannot be compensated by increasing the number of electrodes.
头部模型的准确性会影响脑电图逆问题的求解。如果使用简单的三球体模型以及大脑、颅骨和头皮区域的标准电导率值，偶极子定位可能会出现显著误差。最敏感的头部模型参数之一是颅骨的电导率。一个逼真的三维有限元模型提供了一种方法来研究颅骨不均匀性对脑电图逆问题求解的影响。本文通过针对不同电极数量的计算机模拟，分析了局部颅骨电导率不均匀性对源估计准确性的影响。结果表明，如果不考虑颅骨电导率的不均匀性，在等效电流偶极子估计中可能会出现约1厘米的定位误差。这种建模误差会给解引入偏差，增加电极数量无法补偿该偏差。
