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

다국어 초록 (Multilingual 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.
Materials and 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℃in group W and 33.4±4.3℃ 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).
Conclusion: Artificial ascites are not likely to cause a significant heat-sink phenomenon in the percutaneous RF ablation of the hepatic subcapsular region.

다국어 초록 (Multilingual 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.
Materials and 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℃in group W and 33.4±4.3℃ 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).
Conclusion: Artificial ascites are not likely to cause a significant heat-sink phenomenon in the percutaneous RF ablation of the hepatic subcapsular region.

참고문헌 (Reference)

1 Laeseke PF, "Unintended thermal injuries from radiofrequency ablation: protection with 5% dextrose in water" 186 : S249-S254, 2006

2 Kim YS, "Radiofrequency ablation of the liver in a rabbit model: creation of artificial ascites to minimize collateral thermal injury to the diaphragm and stomach" 17 : 541-547, 2006

3 Hinshaw JL, "Radiofrequency ablation of peripheral liver tumors: intraperitoneal 5% dextrose in water decreases postprocedural pain" 186 : S306-S310, 2006

4 Seung Kwon Kim, "Radiofrequency Ablation of Rabbit Liver In Vivo: Effect of the Pringle Maneuver on Pathologic Changes in Liver Surrounding the Ablation Zone" 대한영상의학회 5 (5): 240-249, 2004

5 Minami Y, "Percutaneous ultrasound-guided radiofrequency ablation with artificial pleural effusion for hepatocellular carcinoma in the hepatic dome" 38 : 1066-1070, 2003

6 Rhim H, "Percutaneous radiofrequency ablation with artificial ascites for hepatocellular carcinoma in the hepatic dome: initial experience" 190 : 91-98, 2008

7 Shibata T, "Percutaneous radiofrequency ablation therapy after intrathoracic saline solution infusion for liver tumor in the hepatic dome" 13 : 313-315, 2002

8 Choi D, "Percutaneous radiofrequency ablation for recurrent hepatocellular carcinoma after hepatectomy: long-term results and prognostic factors" 14 : 2319-2329, 2007

9 Choi D, "Percutaneous radiofrequency ablation for early-stage hepatocellular carcinoma as a first-line treatment: long-term results and prognostic factors in a large single-institution series" 17 : 684-692, 2007

10 Ohmoto K, "Percutaneous microwave coagulation therapy with intraperitoneal saline infusion for hepatocellular carcinoma in the hepatic dome" 172 : 65-66, 1999

11 Ohmoto K, "Percutaneous microwave coagulation therapy using artificial ascites" 176 : 817-818, 2001

12 Raman SS, "Minimizing diaphragmatic injury during radio-frequency ablation: efficacy of subphrenic peritoneal saline injection in a porcine model" 222 : 819-823, 2002

13 Lee YR, "Intraperitoneal saline infusion during radiofrequency ablation of subcapsular hepatic tumor" 16 : 753-754, 2005

14 Kapoor BS, "Injection of subphrenic saline during radiofrequency ablation to minimize diaphragmatic injury" 26 : 302-304, 2003

15 Lu DS, "Effect of vessel size on creation of hepatic radiofrequency lesions in pigs: assessment of the “heat sink” effect" 178 : 47-51, 2002

16 Kim YS, "Completeness of treatment in hepatocellular carcinomas treated with image-guided tumor therapies: evaluation of positive predictive value of contrast-enhanced CT with histopathologic correlation in the explanted liver specimen" 30 : 578-582, 2006

17 Hong SN, "Comparing the outcomes of radiofrequency ablation and surgery in patients with a single small hepatocellular carcinoma and well-preserved hepatic function" 39 : 247-252, 2005