The use of electrical impedance tomography with the inverse problem of EEG and MEG

This study demonstrates the theoretical feasibility of the EIT method to estimate the equivalent electrical conductivities of brain, skull and scalp. On the other hand, it clearly shows that the presented method has the ability to compute equivalent electrical conductivities which compensate for errors committed on the geometry of the head. The use of the EIT estimated conductivities in the solution of the EEG inverse problem (IP) with a wrong head geometry proved to be effective in the decrease of the systematic errors of the dipole position. Also the use of EIT estimated conductivities in the solution of the EEG IP instead of conductivities affected with errors also improves, in general, the dipole position error. It is concluded that the method is not efficient in improving the dipole strength error. It is therefore demonstrated that the combination of EIT and EEG has the potential to reduce systematic errors in estimating the underlying generators of the EEG