The improvement of irreversible electroporation therapy using saline-irrigated electrodes: a theoretical study

Irreversible electroporation (IRE) is a novel therapy used to ablate tumors with high-field electric pulses applied in short durations. It is important to reduce the generation of heat in IRE to avoid the harmful effects of thermal damage. The objective of this simulation study was to examine the effects of saline irrigation in the reduction of heat upon electrodes used in IRE treatment of hepatocellular carcinoma. We used a two dimensional Finite Element Model of a tumor in a liver with electrodes placed at the center of the tumor. We simulated a typical electroporation protocol with varying thicknesses and conductivities of the saline layer, and we observed the maximum temperature and the distribution of the electric field and temperature in the tissue. Our results showed that the maximum temperature in the tissue decreases with the use of saline, but the surface area of the tumor that could potentially be thermally damaged may increase with the thickness and conductivity of the saline. With the use of saline, one can achieve upwards of a 17% reduction of the maximum temperature at the electrodes. Also, the distribution of temperature and the electric field becomes more homogenous between the electrodes as the conductivity of the saline layer increases for all thicknesses of saline. We conclude that irrigating electrodes with saline may be an effective measure to enhance the efficacy of irreversible electroporation by reducing the maximum temperature at the electrodes and also improving the extent and distribution of the electric field in the tissue. However, the properties of the saline should be adjusted so as to limit the increase of thermal damage propagated in the tissue.