title: Does artificial ascites induce the heat-sink phenomenon during percutaneous radiofrequency ablation of the hepatic subcapsular area?: an in vivo experimental study using a rabbit model.
abstract: OBJECTIVE
  To evaluate the effect of the heat-sink phenomenon induced by artificial ascites on the size of the ablation zone during percutaneous radiofrequency (RF) ablation of the hepatic subcapsular area in an in vivo rabbit model.
  
  
  METHODS
  A total of 21 percutaneous rabbit liver RF ablations were performed with and without artificial ascites (5% dextrose aqueous solution). The rabbits were divided into three groups: a) control group (C, n = 7); b) room temperature ascites group (R, n = 7); and c) warmed ascites group (W, n = 7). The tip of a 1 cm, internally cooled electrode was placed on the subcapsular region of the hepatic dome via ultrasound guidance, and ablation was continued for 6 min. Changes in temperature of the ascites were monitored during the ablation. The size of the ablation zones of the excised livers and immediate complications rates were compared statistically between the groups (Mann-Whitney U test, Kruskal-Wallis test, linear-by-linear association, p = 0.05).
  
  
  RESULTS
  One rabbit from the "W" group expired during the procedure. In all groups, the ascites temperatures approached their respective body temperatures as the ablations continued; however, a significant difference in ascites temperature was found between groups "W" and "R" throughout the procedures (39.2+/-0.4 degrees C in group W and 33.4+/-4.3 degrees C in group R at 6 min, p = 0.003). No significant difference was found between the size of the ablation zones (782.4+/-237.3 mL in group C, 1,172.0+/-468.9 mL in group R, and 1,030.6+/-665.1 mL in group W, p = 0.170) for the excised liver specimens. Diaphragmatic injury was identified in three of seven cases (42.9%) upon visual inspection of group "C" rabbits (p = 0.030).
  
  
  CONCLUSIONS
  Artificial ascites are not likely to cause a significant heat-sink phenomenon in the percutaneous RF ablation of the hepatic subcapsular region.
authors.affiliation: Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sunkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Young Sun
authors.initials: YS
authors.lastname: Kim
authors.forename: Hyunchul
authors.initials: H
authors.lastname: Rhim
authors.forename: Dongil
authors.initials: D
authors.lastname: Choi
authors.forename: Hyo K
authors.initials: HK
authors.lastname: Lim
mesh_terms: D000818:Animals; D001201:Ascites; D001831:Body Temperature; D002056:Burns / Q000209:etiology / Q000517:prevention & control; D017115:Catheter Ablation / Q000009:adverse effects / Q000379:methods; D003964:Diaphragm / Q000293:injuries; D005947:Glucose / Q000008:administration & dosage; D008099:Liver / Q000473:pathology / Q000601:surgery*; D011817:Rabbits; D012996:Solutions
chemical_list: D012996:Solutions; D005947:Glucose