title: Percutaneous radiofrequency thermal ablation with hypertonic saline injection: in vivo study in a rabbit liver model.
abstract: OBJECTIVE
  To determine whether hypertonic saline (HS, 36% NaCl) injection prior to or during radiofrequency ablation (RFA) can increase the extent of thermally mediated coagulation in in-vivo rabbit liver tissue, and also to establish the ideal injection time in relation to RFA in order to maximize its effect on the extent of radiofrequency (RF)-induced coagulation.
  
  
  METHODS
  In 26 rabbits, 43 RFA lesions were produced using a 17-gauge internally cooled electrode with a 1-cm active tip under ultrasound (US) guidance. Rabbits were assigned to one of three groups: Group A: RFA alone (n=8); Group B: RFA after the instillation of 1 mL HS (n=8); Group C: RFA after and during the instillation of 0.5 mL HS (n=10). RF energy (30 W) was applied for 3 minutes, and changes occurring in tissue impedance, current, power output, and the temperature of the electrode tip were automatically measured. After RFA, contrast-enhanced spiral CT was performed, and in each group the maximum diameters of the thermal lesions in gross specimens were compared. Technical success and the complications arising were evaluated by CT and on the basis of autopsy findings.
  
  
  RESULTS
  All procedures were technically successful. There were six procedure-related complications (6/26; 23%), including five localized perihepatic hematomas and one thermal injury to the stomach. With instillation of HS in group B rabbits, markedly decreased tissue impedance (73 Omega+/-5) and increased current (704 mA+/-41) were noted, compared to RF ablation without saline infusion (116.3 Omega+/-13, 308 mA+/-80). With instillation of the solution before RFA (group B), coagulation necrosis was greater (14.9 mm+/- 3.8) than in rabbits not injected (group A: 11.5 mm+/-2.4; Group A vs. B: p <.05) and in those injected before and during RFA (group C: 12.5 mm+/-3.1; Group B vs. C: p >.05).
  
  
  CONCLUSIONS
  RFA using HS instillation can increase the volume of RFAinduced necrosis of the liver with a single application, thereby simplifying and accelerating the treatment of larger lesions. In addition, HS instillation before RFA more effectively achieves coagulation necrosis than HS instillation before and during RFA.
authors.affiliation: Department of Diagnostic Radiology, Seoul National University Hospital, Korea. leejm@radcom.snu.ac.kr
authors.forename: Jeong Min
authors.initials: JM
authors.lastname: Lee
authors.forename: Young Kon
authors.initials: YK
authors.lastname: Kim
authors.forename: Young Hwan
authors.initials: YH
authors.lastname: Lee
authors.forename: Sang Won
authors.initials: SW
authors.lastname: Kim
authors.forename: Chun Ai
authors.initials: CA
authors.lastname: Li
authors.forename: Chong Soo
authors.initials: CS
authors.lastname: Kim
mesh_terms: D000818:Animals; D017115:Catheter Ablation; D005240:Feasibility Studies; D008099:Liver / Q000473:pathology / Q000601:surgery*; D008297:Male; D009336:Necrosis; D011817:Rabbits; D012449:Safety; D012462:Saline Solution, Hypertonic / Q000008:administration & dosage / Q000494:pharmacology*; D014057:Tomography, X-Ray Computed
chemical_list: D012462:Saline Solution, Hypertonic