title: Production of Spherical Ablations Using Nonthermal Irreversible Electroporation: A Laboratory Investigation Using a Single Electrode and Grounding Pad.
abstract: OBJECTIVE
  To mathematically model and test ex vivo a modified technique of irreversible electroporation (IRE) to produce large spherical ablations by using a single probe.
  
  
  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 tissue, 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 × 2.21-cm 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.
authors.affiliation: Department of Radiation Oncology and Division of Radiation Physics, Stanford University Medical Center, 875 Blake Wilbur Dr., Stanford, CA 94305. Electronic address: mikesano@stanford.edu.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Sano
authors.affiliation: Department of Urology, Stanford University Medical Center, 875 Blake Wilbur Dr., Stanford, CA 94305.
authors.forename: Richard E
authors.initials: RE
authors.lastname: Fan
authors.affiliation: Division of Vascular and Interventional Radiology and Department of Radiology, Stanford University Medical Center, , 875 Blake Wilbur Dr., Stanford, CA 94305.
authors.forename: Gloria L
authors.initials: GL
authors.lastname: Hwang
authors.affiliation: Department of Urology, Stanford University Medical Center, 875 Blake Wilbur Dr., Stanford, CA 94305.
authors.forename: Geoffrey A
authors.initials: GA
authors.lastname: Sonn
authors.affiliation: Department of Radiation Oncology and Division of Radiation Physics, Stanford University Medical Center, 875 Blake Wilbur Dr., Stanford, CA 94305.
authors.forename: Lei
authors.initials: L
authors.lastname: Xing
mesh_terms: D055011:Ablation Techniques / Q000295:instrumentation*; D000818:Animals; D003198:Computer Simulation; D004566:Electrodes; D018274:Electroporation / Q000295:instrumentation*; D004867:Equipment Design; D020342:Finite Element Analysis; D066298:In Vitro Techniques; D008099:Liver / Q000473:pathology / Q000601:surgery*; D008422:Materials Testing; D009716:Numerical Analysis, Computer-Assisted; D013552:Swine