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CardioVascular and Interventional Radiology

, Volume 33, Issue 5, pp 1028–1032 | Cite as

Optimization of Direct Current–Enhanced Radiofrequency Ablation: An Ex Vivo Study

  • Toshihiro TanakaEmail author
  • Peter Isfort
  • Philipp Bruners
  • Tobias Penzkofer
  • Kimihiko Kichikawa
  • Thomas Schmitz-Rode
  • Andreas H. Mahnken
Technical Note

Abstract

The purpose of this study was to investigate the optimal setting for radiofrequency (RF) ablation combined with direct electrical current (DC) ablation in ex vivo bovine liver. An electrical circuit combining a commercially available RF ablation system with DC was developed. The negative electrode of a rectifier that provides DC was connected to a 3-cm multitined expandable RF probe. A 100-mH inductor was used to prevent electrical leakage from the RF generator. DC was applied for 15 min and followed by RF ablation in freshly excised bovine livers. Electric current was measured by an ammeter. Coagulation volume, ablation duration, and mean amperage were assessed for various DC voltages (no DC, 2.2, 4.5, and 9.0 V) and different RF ablation protocols (stepwise increase from 40 to 80 W, 40 W fixed, and 80 W fixed). Results were compared using Kruskal–Wallis and Mann–Whitney U test. Applying DC with 4.5 or 9.0 V, in combination with 40 W fixed or a stepwise increase of RF energy, resulted in significantly increased zone of ablation size compared with 2.2 V or no DC (P = 0.009). At 4.5 V DC, the stepwise increase of RF energy resulted in the same necrosis size as a 40 W fixed protocol (26.6 ± 3.9 vs. 26.5 ± 4.0 ml), but ablation duration was significantly decreased (296 ± 85 s vs. 423 ± 104 s; P = 0.028). Mean amperage was significantly lower at 4.5 V compared with 9.0 V (P = 0.028). Combining a stepwise increase of RF energy with a DC voltage of 4.5 V is most appropriate to increase coagulation volume and to minimize procedure time.

Keywords

Radiofrequency ablation Liver tumor Direct current 

Notes

Acknowledgments

The authors acknowledge the excellent technical support of Elmar Junker and Tomas Finocciaro.

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Copyright information

© Springer Science+Business Media, LLC and the Cardiovascular and Interventional Radiological Society of Europe (CIRSE) 2010

Authors and Affiliations

  • Toshihiro Tanaka
    • 1
    • 3
    Email author
  • Peter Isfort
    • 1
    • 2
  • Philipp Bruners
    • 1
    • 2
  • Tobias Penzkofer
    • 1
    • 2
  • Kimihiko Kichikawa
    • 3
  • Thomas Schmitz-Rode
    • 1
  • Andreas H. Mahnken
    • 1
    • 2
  1. 1.Applied Medical Engineering, Helmholtz-Institute AachenRWTH Aachen UniversityAachenGermany
  2. 2.Department of Diagnostic RadiologyAachen University Hospital, RWTH Aachen UniversityAachenGermany
  3. 3.Department of RadiologyNara Medical UniversityNaraJapan

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