title: Optimizing Irreversible Electroporation Ablation with a Bipolar Electrode.
abstract: OBJECTIVE
  To optimize single-insertion bipolar irreversible electroporation (IRE) by characterizing effects of electric parameters and controlling tissue electric properties in a porcine model.
  
  
  METHODS
  Single-insertion electrode bipolar IRE was performed in 28 in vivo pig livers (78 ablations). First, effects of voltage (2,700-3,000 V), number of pulses, repeated cycles (1-6 cycles), and pulse width (70-100 µs) were studied. Next, electric conductivity was altered by instillation of hypertonic and hypotonic fluids. Finally, effects of thermal stabilization were assessed using internal electrode cooling. Treatment effect was evaluated 2-3 hours after IRE. Dimensions were compared and subjected to statistical analysis.
  
  
  RESULTS
  Delivering 3,000 V at 70 µs for a single 90-pulse cycle yielded 3.8 cm ± 0.4 × 2.0 cm ± 0.3 of ablation. Applying 6 cycles of energy increased ablation to 4.5 cm ± 0.4 × 2.6 cm ± 0.3 (P < .001). Further increasing pulse lengths to 100 µs (6 cycles) increased ablation to 5.0 cm ± 0.4 × 2.9 cm ± 0.3 (P < .001) but resulted in electric spikes and system crashes in 40%-50% of cases. Increasing tissue electric conductivity via hypertonic solution instillation in surrounding tissues increased frequency of generator crashes, whereas continuous instillation of distilled water eliminated this arcing phenomenon but reduced ablation to 2.3 cm ± 0.1. Controlled instillation of distilled water when electric arcing was suspected from audible popping produced ablations of 5.3 cm ± 0.6 × 3.1 cm ±0.3 without crashes. Finally, 3.1 cm ± 0.1 short-axis ablation was achieved without system crashes with internal electrode perfusion at 37°C versus 2.3 cm ± 0.1 with 4°C-10°C perfusion (P < .001).
  
  
  CONCLUSIONS
  Bipolar IRE ablation zones can be increased with repetitive high voltage and greater pulse widths accompanied by either judicious instillation of hypotonic fluids or internal electrode perfusion to minimize unwanted electric arcing.
authors.affiliation: Department of Diagnostic Imaging, Hadassah Hebrew University Medical Center, POB 12000, Ein Kerem, Jerusalem 9112001, Israel; Department of Diagnostic Imaging, Wolfson Medical Center, affiliated with the Sackler Faculty of Medicine, Tel-Aviv University, Holon, Israel.
authors.forename: Ayelet
authors.initials: A
authors.lastname: Wandel
authors.affiliation: Department of Diagnostic Imaging, Hadassah Hebrew University Medical Center, POB 12000, Ein Kerem, Jerusalem 9112001, Israel. Electronic address: elib@hadassah.org.il.
authors.forename: Eliel
authors.initials: E
authors.lastname: Ben-David
authors.affiliation: Department of Diagnostic Imaging, Hadassah Hebrew University Medical Center, POB 12000, Ein Kerem, Jerusalem 9112001, Israel.
authors.forename: B Said
authors.initials: BS
authors.lastname: Ulusoy
authors.affiliation: AngioDynamics, Latham, New York.
authors.forename: Robert
authors.initials: R
authors.lastname: Neal
authors.affiliation: Department of Surgery, Hadassah Hebrew University Medical Center, POB 12000, Ein Kerem, Jerusalem 9112001, Israel.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Faruja
authors.affiliation: Department of Diagnostic Imaging, Hadassah Hebrew University Medical Center, POB 12000, Ein Kerem, Jerusalem 9112001, Israel.
authors.forename: Isaac
authors.initials: I
authors.lastname: Nissenbaum
authors.affiliation: Department of Diagnostic Imaging, Hadassah Hebrew University Medical Center, POB 12000, Ein Kerem, Jerusalem 9112001, Israel.
authors.forename: Svetlana
authors.initials: S
authors.lastname: Gourovich
authors.affiliation: Department of Diagnostic Imaging, Hadassah Hebrew University Medical Center, POB 12000, Ein Kerem, Jerusalem 9112001, Israel.
authors.forename: S Nahum
authors.initials: SN
authors.lastname: Goldberg
mesh_terms: D055011:Ablation Techniques / Q000295:instrumentation*; D000818:Animals; D004553:Electric Conductivity; D004566:Electrodes; D018274:Electroporation / Q000295:instrumentation*; D004867:Equipment Design; D005260:Female; D006982:Hypertonic Solutions / Q000737:chemistry; D007038:Hypotonic Solutions / Q000737:chemistry; D066298:In Vitro Techniques; D008099:Liver / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D008422:Materials Testing; D034421:Sus scrofa; D013997:Time Factors; D014463:Ultrasonography
chemical_list: D006982:Hypertonic Solutions; D007038:Hypotonic Solutions