Use of a-priori knowledge on the geometry, the upper and the lower bounds of the tissue resistivities in order to estimate in vivo resistivities, in ElectricaI impedance tomography (EIT), is assessed. For the central regions, estimation error is higher due to decreased sensitivity at the center. At the peripheral regions the sensitivity is higher, resulting in lower estimation errors. Increasing the number of drive pairs from a single drive pair (as implemented in B.M. Eyuboglu et al., Phys. Med. Biol., vol. 39, p. 1-17, 1994) to 8 pairs improves the estimation error up to 37 times for the insulator and up to 5 times for the conductor regions. The authors' results suggests that the MiMSEE algorithm of B.M. Eyuboglu et al. can be improved further, including all possible drive pairs.