title: A novel electrode with electromagnetic tip tracking in ultrasonography-guided radiofrequency ablation: a phantom, ex vivo, and in vivo experimental study.
abstract: OBJECTIVE
  The objective of this study was to compare the targeting and ablation performance between a newly developed radiofrequency (RF) electrode embedded with an electromagnetic position sensor (EMPS) at the electrode tip and a conventional RF electrode.
  
  
  METHODS
  The institutional animal care and use committee approved this study. The targeting of paint balls within phantoms was performed under ultrasonography guidance by 2 radiologists (beginner vs expert) with an "in-plane" and "out-of-plane" approaches using the new RF electrode and a conventional RF electrode (n = 20 for each method). To evaluate the targeting performance, the electrode placement time and the number of electrode pullbacks for redirection were compared between the 2 electrodes. The ablation performance was also compared by analyzing the ablation volumes in ex vivo bovine and in vivo porcine livers (n = 30 and n = 24, respectively) and the cellular viability of the ablation zone in in vivo specimens.
  
  
  RESULTS
  In the phantom study, the RF electrode embedded with an EMPS showed a significantly shorter electrode placement time compared with the conventional RF electrode in both the in-plane and out-of-plane approaches by both radiologists (P < 0.05). The electrode pullback rate for both radiologists was lower in the new RF electrode than in the conventional RF electrode, but it did not reach statistical significance in the in-plane approach by the expert (P = 0.059). The ablation volumes analyzed with and without cellular viability in the ex vivo and in vivo studies were not significantly different between the 2 electrodes (P > 0.05).
  
  
  CONCLUSIONS
  The RF electrode embedded with an EMPS is faster than the conventional electrode in the electrode placement into the target lesions. The ablation performance is not significantly different between the 2 electrodes.
authors.affiliation: From the *Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University, School of Medicine; and †Animal Laboratory and Research Center, Samsung Biomedical Research Institute, Samsung Medical Center, Seoul, Republic of Korea.
authors.forename: Tae Wook
authors.initials: TW
authors.lastname: Kang
authors.forename: Min Woo
authors.initials: MW
authors.lastname: Lee
authors.forename: Seung Hee
authors.initials: SH
authors.lastname: Choi
authors.forename: Hyunchul
authors.initials: H
authors.lastname: Rhim
authors.forename: Sanghyeok
authors.initials: S
authors.lastname: Lim
authors.forename: Kyoung Doo
authors.initials: KD
authors.lastname: Song
authors.forename: Ji Hye
authors.initials: JH
authors.lastname: Min
authors.forename: Seo-youn
authors.initials: SY
authors.lastname: Choi
authors.forename: Hyo Keun
authors.initials: HK
authors.lastname: Lim
authors.forename: Jehoon
authors.initials: J
authors.lastname: Yang
mesh_terms: D000818:Animals; D017115:Catheter Ablation / Q000295:instrumentation*; D002417:Cattle; D004574:Electromagnetic Fields; D066298:In Vitro Techniques; D008099:Liver / Q000000981:diagnostic imaging / Q000601:surgery*; D008280:Magnetics / Q000295:instrumentation*; D019047:Phantoms, Imaging; D025321:Surgery, Computer-Assisted / Q000295:instrumentation*; D014463:Ultrasonography / Q000295:instrumentation*