ESTIMATION OF CONDUCTIVITY CHANGES IN A REGION OF INTEREST WITH ELECTRICAL IMPEDANCE TOMOGRAPHY

(Communicated by the associate editor name) Abstract. This paper proposes a novel approach to reconstruct changes in a target conductivity from electrical impedance tomography measurements. As in the conventional difference imaging, the reconstruction of the conductivity change is based on electrical potential measurements from the exterior bound-ary of the target before and after the change. In this paper, however, images of the conductivity before and after the change are reconstructed simultaneously based on the two data sets. The key feature of the approach is that the conduc-tivity after the change is parameterized as a linear combination of the initial state and the change. This allows for modeling independently the spatial char-acteristics of the background conductivity and the change of the conductivity-by separate regularization functionals. The approach also allows in a straight-forward way the restriction of the conductivity change to a localized region of interest inside the domain. While conventional difference imaging reconstruc-tion is based on a global linearization of the observation model, the proposed approach amounts to solving a non-linear inverse problem. The feasibility of the proposed reconstruction method is tested experimentally and with a sim-ulation which demonstrates a potential new medical application of electrical impedance tomography: imaging of vocal folds in voice loading studies. 1. Introduction. In electrical impedance tomography (EIT), electrical currents are injected into an object using a set of electrodes attached on the boundary of the object and the resulting electrode potentials are measured. The conductivity of the object is reconstructed as a spatially distributed parameter based on the know