Effects of Warping Finite Element Meshes for the Forward Model of the Head in Eit

The use of realistic FE head models in EIT of brain function confers significant advantages, but image quality is critically dependent on mesh geometrical integrity. Generation of accurate models for individual subjects is time-consuming, so warping an existing idealised mesh to closely approximate specific patient geometry is being investigated. The head was modelled as an ellipsoid to obtain simulated boundary voltages calculated with both a homogeneous mesh of 11820 elements and a shelled mesh of 13985 elements. Images were reconstructed with a linear, truncated SVD algorithm, using spheres linearly warped to the same dimensions as the ellipsoid, with 29435 and 29832 elements for homogeneous and shelled models respectively. Decrease of mesh quality and localisation errors were acceptable in both cases, thus leading towards the conclusion that this method could be uniquely useful for EIT imaging in conditions like acute stroke where it may not be practicable to obtain an individual MRI and mesh