Electric Field Distribution in Ex Vivo Muscle Tissue with Anisotropic Conductivity Values at a Millimeter Scale Obtained by Using DT-MREIT

摘要

Magnetic resonance electrical impedance tomography (MREIT) has shown that cross-sectional imaging of an isotropic conductivity distribution with a spatial resolution of a few millimeters is feasible. Using the acquired conductivity values, we may quantitatively visualize an electric field distribution for uses in electroporation. Since some biological tissues are anisotropic, however, it is desirable to extend the method to anisotropic objects. Lately, a new anisotropic conductivity tensor imaging method called DT-MREIT has been proposed by combining diffusion tensor MRI (DT-MRT) and MREIT. In this paper, we adopted this new method to reconstruct anisotropic conductivity tensor images of ex vivo muscle tissues. We found that the degree of anisotropy in muscle tissue at a millimeter scale is about 1.32, which is smaller than previous findings from electrical measurements using electrodes at a centimeter scale. Using the recovered anisotropic conductivity values, we visualized the voltage, current density and electric field distributions in tissues during simulated electroporation. Since the effects of tissue anisotropy on electroporation depends on the degree of anisotropy, accurate estimation of anisotropic conductivity values of a target tissue is important for electroporation planning and monitoring.