Incorporating electroporation-related conductivity changes into models for the calculation of the electric field distribution in tissue

Abstract

Electroporation is a phenomenon caused by externally applied high-intensity electric field to cells that results in the increase of cell membrane permeability to ions and various molecules such as drugs or DNA. In vivo tissue electroporation is the basis for electochemotherapy and electrogenetherapy. Apart from the increased membrane permeability which is observed long after the delivery of electric pulses, there is experimental evidence that, during the application of membrane permeabilizing electric pulses electric conductivity of tissue increases. In this work we use 3D finite-element modeling approach to investigate the difference in electroporated tissue volume when tissue conductivity change due to electroporation is taken into account vs. constant conductivity case. We modeled needle electrodes and assumed that tissue has sigmoid-like conductivity dependence on electric field intensity. Our numerical studies showed that taking into account dependence of tissue conductivity on electric field intensity affects the electric field distribution in tissue and in consequence irreversibly and reversibly electroporated regions. For model validation we calculated the reaction current and compared it with results of previous study where current was measured during in vivo tissue electroporation on experimental animals. We found reasonably close match between the calculated current in our nonlinear model and current measured in the experiment. © 2010 International Federation for Medical and Biological Engineering.