In this paper, we consider the impedance tomography problem of estimat
ing the conductivity distribution within the body from static current/
voltage measurements on the body's surface. We present a new method of
implementing prior information of the conductivities in the optimizat
ion algorithm. The method is based on the approximation of the prior c
ovariance matrix by simulated samples of feasible conductivities. The
reduction of the dimensionality of the optimization problem is perform
ed by principal component analysis (PCA).