A standardized boundary element method volume conductor model
A standardized boundary element method volume conductor model
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DOI：
10.1016/s1388-2457(02)00030-5
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发表时间：
2002-05-01
影响因子：
4.7
通讯作者：
Ebersole, JS
中科院分区：
文献类型：
--
作者：
Fuchs, M;Kastner, J;Ebersole, JS
目的：我们使用来自平均磁共振图像（MRI）数据集（蒙特利尔神经学研究所）的3室边界元方法（BEM）模型，与单独导出的模型相比，为了提供简单的接近真实形状的体积导体模型进行震源重建。将电极位置转换为模型的坐标系，将最优偶极子拟合结果转换回原坐标系。通过与模拟数据的比较以及与几个患者的癫痫峰数据的个别BEM模型的比较，验证了新方法的定位准确性。方法：标准BEM模型共有4770个节点，分别描述光滑的皮质包膜、颅骨外部和皮肤外部。利用3-5个基准点将电极位置转换为模型坐标系。左和右耳前点，顶点，和齿轮)。该变换由平均比例因子和刚性变换（平移和旋转）组成。利用外边界元室三角网存储的传递矩阵，通过线性插值计算变换电极位置的电势值。源重构后，通过对第一个变换矩阵进行逆变换，将最适合的偶极子结果变换回原坐标系。结果：在高度精细的参考BEM模型中，随机位置和随机方向的测试偶极子被用来模拟无噪声数据。利用球面和标准化边界元体积导体模型重建的源结果与已知偶极子位置进行了比较。球形头部模型导致大脑底部定位错误。将标准化BEM模型应用于7例患者的平均和非平均癫痫峰数据。将源重建结果与3个球壳模型和基于单个MRI数据集的单个BEM模型的重建结果进行比较。在球形头模型中发现了与模拟结果相似的明显误差。标准化和个性化BEM模型具有可比性。结论：这种新的头部建模方法明显优于简单的球壳近似。尤其是在脑基底区，包括颞叶。通过对BEM设置使用标准化的头，与从单个三维MRI数据中获得特定模型相比，它可以更容易、更快速地获得真实形状的体积导体模型。(C) 2002爱思唯尔科学爱尔兰有限公司版权所有。
Objectives: We used a 3-compartment boundary element method (BEM) model from an averaged magnetic resonance image (MRI) data set (Montreal Neurological Institute) in order to provide simple access to realistically shaped volume conductor models for source reconstruction, as compared to individually derived models. The electrode positions were transformed into the model's coordinate system, and the best fit dipole results were transformed back to the original coordinate system. The localization accuracy of the new approach was tested in a comparison with simulated data and with individual BEM models of epileptic spike data front several patients.Methods: The standard BEM model consisted of a total of 4770 nodes, which describe the smoothed cortical envelope, the outside of the skull, and the outside of the skin. The electrode positions were transformed to the model coordinate system by using 3-5 fiducials (nasion. left and right preauricular points, vertex, and inion). The transformation consisted of an averaged scaling factor and a rigid transformation (translation and rotation). The potential values at the transformed electrode positions were calculated by linear interpolation from the stored transfer matrix of the outer BEM compartment triangle net. After source reconstruction the best fit dipole results were transformed back into the original coordinate system by applying the inverse of the first transformation matrix.Results: Test-dipoles at random locations and with random orientations inside of a highly refined reference BEM model were used to simulate noise-free data. Source reconstruction results using a spherical and the standardized BEM volume conductor model were compared to the known dipole positions. Spherical head models resulted in mislocation errors at the base of the brain. The standardized BEM model was applied to averaged and unaveraged epileptic spike data from 7 patients. Source reconstruction results were compared to those achieved by 3 spherical shell models and individual BEM models derived front the individual MRI data sets. Similar errors to that evident with simulations were noted with spherical head models. Standardized and individualized BEM models were comparable.Conclusions: This new approach to head modeling performed significantly better than a simple spherical shell approximation. especially in basal brain areas, including the temporal lobe. By using a standardized head for the BEM setup, it offered an easier and faster access to realistically shaped volume conductor models as compared to deriving specific models from individual 3-dimensional MRI data. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.