Awada K A, Jackson D R, Baumann S B, Williams J T, Wilton D R, Fink P W, Prasky B R
Department of Neurological Surgery, Presbyterian University Hospital, Pittsburgh, PA 15213, USA.
IEEE Trans Biomed Eng. 1998 Sep;45(9):1135-45. doi: 10.1109/10.709557.
This paper presents a sensitivity study of electroencephalography-based source localization due to errors in the head-tissue conductivities and to errors in modeling the conductivity variation inside the brain and scalp. The study is conducted using a two-dimensional (2-D) finite element model obtained from a magnetic resonance imaging (MRI) scan of a head cross section. The effect of uncertainty in the following tissues is studied: white matter, gray matter, cerebrospinal fluid (CSF), skull, and fat. The distribution of source location errors, assuming a single-dipole source model, is examined in detail for different dipole locations over the entire brain region. We also present a detailed analysis of the effect of conductivity on source localization for a four-layer cylinder model and a four-layer sphere model. These two simple models provide insight into how the effect of conductivity on boundary potential translates into source location errors, and also how errors in a 2-D model compare to errors in a three-dimensional model. Results presented in this paper clearly point to the following conclusion: unless the conductivities of the head tissues and the distribution of these tissues throughout the head are modeled accurately, the goal of achieving localization accuracy to within a few millimeters is unattainable.
本文针对基于脑电图的源定位进行了敏感性研究，该研究涉及头部组织电导率误差以及大脑和头皮内部电导率变化建模误差。该研究使用从头部横截面的磁共振成像（MRI）扫描获得的二维（2-D）有限元模型进行。研究了以下组织中不确定性的影响：白质、灰质、脑脊液（CSF）、颅骨和脂肪。假设为单偶极子源模型，详细研究了整个脑区不同偶极子位置的源定位误差分布。我们还对四层圆柱模型和四层球体模型的电导率对源定位的影响进行了详细分析。这两个简单模型有助于深入了解电导率对边界电位的影响如何转化为源定位误差，以及二维模型中的误差与三维模型中的误差如何比较。本文给出的结果清楚地表明了以下结论：除非准确模拟头部组织的电导率以及这些组织在整个头部的分布，否则将定位精度控制在几毫米以内的目标是无法实现的。
