Cuffin B N
Frances Bitter National Magnet Laboratory, Massachusetts Institute of Technology, Cambridge 02139.
IEEE Trans Biomed Eng. 1993 Jan;40(1):42-8. doi: 10.1109/10.204770.
Many studies have been performed on the effects of various features of head geometry on electroencephalograms (EEG's) and magnetoencephalograms (MEG's) and on the accuracy with which electrical sources in the brain can be localized using these measurements. However, to date no studies have been performed of the effects of local variations in skull and scalp thickness. This paper presents a computer modeling study of the effects of such local variations. The results obtained in this study indicate that local variations in skull and scalp thickness have effects on EEG's and MEG's which range from a simple intuitive effect to complex effects which depend on such factors as source depth and orientation, the geometry of the variation in skull and scalp thickness, etc. These results also indicate that local variations in skull and scalp thickness cause EEG localization errors which are generally much less than 1 cm and MEG localization errors which are even smaller. These results also indicate that multichannel and single-channel MEG measurements will produce localization errors of approximately the same amplitude when there is a bump on the external surface of the head but that multichannel measurements will produce significantly smaller localization errors than single-channel measurements when a depression is present in that surface.
已经开展了许多研究，探讨头部几何结构的各种特征对脑电图（EEG）和脑磁图（MEG）的影响，以及利用这些测量来定位脑内电信号源的准确性。然而，迄今为止，尚未有关于颅骨和头皮厚度局部变化影响的研究。本文介绍了一项关于此类局部变化影响的计算机建模研究。本研究获得的结果表明，颅骨和头皮厚度的局部变化对EEG和MEG有影响，其范围从简单直观的影响到复杂的影响，这些复杂影响取决于诸如源深度和方向、颅骨和头皮厚度变化的几何形状等因素。这些结果还表明，颅骨和头皮厚度的局部变化导致的EEG定位误差通常远小于1厘米，MEG定位误差甚至更小。这些结果还表明，当头部外表面有凸起时，多通道和单通道MEG测量产生的定位误差幅度大致相同，但当该表面存在凹陷时，多通道测量产生的定位误差比单通道测量小得多。
