MAGNETIC-RESONANCE MICROSCOPY OF ELECTRIC CURRENTS

Current-density imaging (CDI) is a new and encouraging achievement of MRI techniques development. The first experiments measuring electric-c urrent distribution by MRI focused on the demonstration of the feasibi lity of the method on large water phantoms, where sensitivity consider ations and limitations were considered. In this paper, electric curren ts through small conductive samples were measured. A series of 2D elec tric-current distributions through the selected slice with a plane res olution of 60 X 60 mu m is presented. A theory for optimal sensitivity and resolution is established and compared to experimental data. Rela xation properties of the sample and diffusion effects, which influence these results significantly in the presence of large gradients, are e mphasized. Finally, the power of CDI is demonstrated on a biologically relevant experiment-plant-stem electric-conductivity imaging. (C) 199 4 Academic Press, Inc.