title: Radiofrequency ablation of liver adjacent to body of gallbladder: histopathologic changes of gallbladder wall in a pig model.
abstract: OBJECTIVE
  The purpose of our study was to evaluate the histopathologic changes of gallbladder wall surrounding radiofrequency ablation zones in pig livers and to assess the risk factors for thermal injury of gallbladder wall in terms of distance of the electrode, electrode direction in relation to the gallbladder wall, and time of sacrifice of the animal.
  
  
  METHODS
  The study was performed in 15 pigs using an internally cooled single electrode with a 1-cm electrically active tip under sonographic guidance. Twenty-three hepatic ablation zones abutting the gallbladder were analyzed in three phases on the basis of the distance of the electrode (group A, 0.5 cm; group B, 1.0 cm), electrode direction (perpendicular or parallel), and time of sacrifice (immediate or delayed [7 days after radiofrequency ablation]). We evaluated the gross changes, the depth of thermal injury, and the grade of abnormal microscopic changes in the gallbladder wall. Data analysis was performed on the basis of the Fisher's exact test.
  
  
  RESULTS
  Discoloration and perforation were more frequent in group A (60%, 6/10, and 20%, 2/10, respectively) than in group B (25%, 2/8, and 0%, respectively, p > 0.05). Perforation was more frequent in the parallel direction and delayed phase (33.3%, 1/3, and 40%, 2/5, respectively) compared with the perpendicular direction and immediate phase (14.3%, 1/7, and 0%, respectively, p > 0.05). Depth of thermal injury showed a significant difference between group A and group B for full-thickness involvement (53.8%, 7/13, versus 0%, respectively, p < 0.05). Abnormal microscopic changes showed that parallel direction and immediate phase were more frequent with full-thickness involvement (71.4%, 5/7, and 71.4%, 5/7, respectively) compared with perpendicular direction and delayed phase (33.3%, 2/6, and 33.3%, 2/6, respectively, p > 0.05).
  
  
  CONCLUSIONS
  Hepatic radiofrequency ablation abutting the gallbladder can produce substantial thermal injury of the gallbladder wall, including perforation, especially when performed without a safe distance.
authors.affiliation: Department of Radiology, Kangwon National University College of Medicine, Kangwon-do, South Korea.
authors.forename: Jiwon
authors.initials: J
authors.lastname: Lee
authors.forename: Hyunchul
authors.initials: H
authors.lastname: Rhim
authors.forename: Yong Hwan
authors.initials: YH
authors.lastname: Jeon
authors.forename: Hyo K
authors.initials: HK
authors.lastname: Lim
authors.forename: Won Jae
authors.initials: WJ
authors.lastname: Lee
authors.forename: Dongil
authors.initials: D
authors.lastname: Choi
authors.forename: Young-Sun
authors.initials: YS
authors.lastname: Kim
mesh_terms: D000818:Animals; D017115:Catheter Ablation / Q000009:adverse effects* / Q000379:methods; D004195:Disease Models, Animal; D005704:Gallbladder / Q000293:injuries* / Q000473:pathology*; D006498:Hepatectomy / Q000009:adverse effects* / Q000379:methods; D013552:Swine