Possibilities and problems of real-time imaging of tissue resistivity.

We show that the surface potential profiles used for electrical impedance tomography are largely determined by body shape and to a much lesser extent by internal resistivity distribution. The results of 2D finite element modelling show that changes of profile amplitude greater than a factor of four can be expected for the thorax. This offers the possibility of determining body shape from surface potential profiles and hence the determination of static images. Some of the other problems and possibilities of impedance imaging are discussed and in particular the design of a system for real time cardiac gated imaging.