Production of Spherical Ablations Using Nonthermal Irreversible Electroporation: A Laboratory Investigation Using a Single Electrode and Grounding Pad

Purpose: To mathematically model-and test ex vivo, a modified technique of irreversible electroporation (IRE) to produce large spherical ablations by using a single probe. Materials and Methods: Computed Simulations were performed by using varying voltages, electrode exposure lengths, and tissue types. A vegetable (potato) tissue model was then used to compare ablations created by conventional and high-frequency IRE protocols by using 2 probe configurations: a single probe with two collinear electrodes (2EP) or a single, electrode configured with a grounding pad (P+GP) The new P+GP electrode configuration was evaluated in ex vivo liver tissue. Results:,The P+GP configuration prodUced more spherical ablation volumes than the 2EP configuration in computed simulations and tissue models. In prostate tissue, computed simulations predicted ablation volumes at 3,000 V of 1.6 cm(3) for the P+GP configurations, compared with 0.94-cm(3) for the 2EP configuration; in liver fissile, the predicted ablation volumes were 4.7 times larger than those in the prostate. Vegetable model studies verify that the P+GP configuration produces larger and more spherical ablations than those produced by the 2EP. High-frequency IRE-treatment of ex vivo liver with the P+GP configuration created a 2.84 x 2.21cm ablation zone. Conclusions: computer modeling showed that P+GP configuration for IRE procedures yields ablations that are larger than the, 2EP configuration, creating substantial ablation zones with a single electrode placement. When tested in tissue Models and an ex vivo liver model, the P+GP configuration created ablation zones that appear to be-of clinically relevant size and shape.