title: Feasibility of a Low-Power Radiofrequency Ablation Protocol to Delay Steam Popping.
abstract: OBJECTIVE
  Steam popping frequently occurs during conventional high-power radiofrequency (RF) ablation, increasing the risk of tumor spread. The aim of this study was to evaluate the effect of a low-power RF ablation protocol on the intensity and timing of steam popping in ex vivo bovine liver.
  
  
  METHODS
  High-power (maximum 200 W; group 1) and low-power (maximum 70 W; group 2) RF ablation protocols were established. In the first phase, RF ablation was conducted for 12 min. Ablation volume, intensity, and timing of maximal popping sounds and total energy generated for RF ablation were compared between groups 1 and 2. In the second phase, RF ablation was conducted until maximal popping occurred, and ablation zones on histologic specimens were compared.
  
  
  RESULTS
  Relative to group 1, maximal popping occurred at significantly delayed timing in group 2 (50 s ± 11 vs 397 s ± 117; P < .001), but without a difference in intensity (ratios vs reference sound of 0.70 ± 0.18 vs 0.83 ± 0.26; P = .138). The ablation volume after 12 min of RF ablation did not differ between groups 1 and 2 (18.46 cm(3) ± 1.35 vs 15.78 cm(3) ± 0.64; P = .086). However, in the histologic specimens obtained when maximal popping occurred, the area of complete coagulative necrosis was significantly larger in group 2 (P < .05).
  
  
  CONCLUSIONS
  Low-power RF ablation delays steam popping while providing comparable therapeutic effects to high-power RF ablation. Delaying maximal popping may prevent tumor cell dispersion because maximal popping occurs after an adequate ablation zone has been achieved.
authors.affiliation: Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Jooae
authors.initials: J
authors.lastname: Choe
authors.affiliation: Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Kyung Won
authors.initials: KW
authors.lastname: Kim
authors.affiliation: Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Seoul, Korea; Department of Radiology, Seoul National University College of Medicine, Seoul, Korea; Department of Radiology, Sheikh Khalifa Specialty Hospital, Ras Al Khaimah, United Arab Emirates.
authors.forename: Young Il
authors.initials: YI
authors.lastname: Kim
authors.affiliation: Department of Radiology, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Jin Wook
authors.initials: JW
authors.lastname: Chung
authors.affiliation: Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Seoul, Korea; Center for Bioimaging of New Drug Development, Asan Institute for Life Sciences, Asan Medical Center, Seoul, Korea; Department of Radiology, Seoul National University College of Medicine, Seoul, Korea; RF Medical, Seoul, Korea; Department of Radiology, Sheikh Khalifa Specialty Hospital, Ras Al Khaimah, United Arab Emirates.
authors.forename: Jimi
authors.initials: J
authors.lastname: Huh
authors.affiliation: Center for Bioimaging of New Drug Development, Asan Institute for Life Sciences, Asan Medical Center, Seoul, Korea.
authors.forename: Jisuk
authors.initials: J
authors.lastname: Park
authors.affiliation: Center for Bioimaging of New Drug Development, Asan Institute for Life Sciences, Asan Medical Center, Seoul, Korea.
authors.forename: Su Jung
authors.initials: SJ
authors.lastname: Ham
authors.affiliation: RF Medical, Seoul, Korea.
authors.forename: Myong Ki
authors.initials: MK
authors.lastname: Jun
authors.affiliation: Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Seoul, Korea. Electronic address: pnkim@amc.seoul.kr.
authors.forename: Pyo Nyun
authors.initials: PN
authors.lastname: Kim
mesh_terms: D000818:Animals; D017115:Catheter Ablation / Q000379:methods*; D002417:Cattle; D005240:Feasibility Studies; D066298:In Vitro Techniques; D008099:Liver / Q000601:surgery*; D011846:Radio Waves; D013227:Steam
chemical_list: D013227:Steam