Electrical resistance tomography (ERT) is a relatively new imaging modality in which the internal resistivity distribution is reconstructed based on the known sets of injected currents and induced voltages on the surface of the object. In this paper, a dynamic ERT imaging technique is described for the case where the resistivity distribution inside the object changes rapidly within the time taken to acquire a full set of independent measurement data. In doing so, the inverse problem is treated as the nonlinear state estimation problem and the unknown state (resistivity) is estimated with the aid of extended Kalman filter. In particular, additional internal electrode is attached to the known internal structure of the object to enhance the reconstruction performance. The generalized Tikhonov regularization technique is employed to mitigate the ill-posedness of the inverse problem. Computer simulations are provided to illustrate the reconstruction performance of the proposed algorithm.