Three-dimensional electrical impedance tomography based on the complete electrode model

In electrical impedance tomography an approximation for the internal resist ivity distribution is computed based on the knowledge of the injected curre nts and measured voltages on the surface of the body, It is often assumed t hat the injected currents are confined to the two-dimensional (2-D) electro de plane and the reconstruction is based on 2-D assumptions, However, the c urrents spread out in three dimensions and, therefore, off-plane structures have significant effect on the reconstructed images. In this paper we prop ose a finite element-based method for the reconstruction of three-dimension al resistivity distributions, The proposed method is based on the so-called complete electrode model that takes into account the presence of the elect rodes and the contact impedances, Both the forward and the inverse problems are discussed and results from static and dynamic (difference) reconstruct ions with real measurement data are given, It is shown that in phantom expe riments with accurate finite element computations it is possible to obtain static images that are comparable with difference images that are reconstru cted from the same object with the empty (saline filled) tank as a referenc e.