| Carsten Wolters, Alfred Anwander, Guntram Berti, Ulrich Hartmann: Geometry–adapted hexahedral meshes improve accuracy of finite element method based EEG source analysis. IEEE Transactions on Biomedical Engineering, 54, no. 8 (2007) |
| Mesh generation in finite element method based EEG source analysis generally influences greatly the accuracy of the results. It is thus important to determine a meshing strategy well adopted to achieve both acceptable accuracy for potential distributions and reasonable computation times. In this paper, we propose to achieve this goal by smoothing regular hexahedral finite elements at material interfaces using a node-shift approach. We evaluate regular and smoothed elements in a four-layer sphere model for both a subtraction and a direct potential approach and compare their accuracy. On the average, node-shifting reduces both topography and magnitude errors by more than a factor of 2 for tangential and 1.5 for radial sources. Nevertheless, node-shifting has to be carried out with caution for sources located within or close to irregular hexahedra, because extreme deformations might lead to larger overall errors. With regard to realistic head modeling, node-shifted hexahedra should thus be used for the skin and skull compartments while we would not recommend deforming elements at the grey and white matter surfaces. |