Bioelectrical impedance techniques in medicine. Part III: Impedance imaging. Second section: reconstruction algorithms.

This section is devoted to the reconstruction algorithms published in the literature and developed for reconstructing the electrical conductivity and permittivity inside a body from measurements made on the body surface. These algorithms fall into two main categories. The first, based on linear approximations, are noniterative methods assuming that conductivity does not differ very much from a constant. Examples of noniterative methods are the Barber-Brown back-projection method and related methods, the Calderon's approach, the moment method, and one-step Newton methods. The second class of methods consists of iterative methods, which typically include output least squares for various functions. A related class includes the adaptive methods, in which the applied patterns of current are adjusted to get the best signal. A review of all these different alternatives is presented.