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

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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.

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Most cited references 17

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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.

Kwang Cheol Koh, Alice W. Lee, Jennifer Lim … (2007)

The purpose of this study was to evaluate the long-term survival results and complications of percutaneous radiofrequency ablation (RFA) in patients with early-stage hepatocellular carcinoma (HCC). Between April 1999 and May 2005, 570 patients with 674 early-stage HCCs underwent percutaneous RFA as a first-line treatment option in a single institution. We evaluated the effectiveness rates, local tumor progression rates, survival rates, and complications. We also assessed the prognostic values of survival rates by using Cox proportional hazard models. The primary technique effectiveness rate was 96.7% (652 of 674). The cumulative rates of local tumor progression at 1, 2, and 3 years were 8.1%, 10.9%, and 11.8%, respectively. The cumulative survival rates at 1, 2, 3, 4, and 5 years were 95.2%, 82.9%, 69.5%, 60.8%, and 58.0%, respectively. Patients with Child-Pugh class A cirrhosis, of younger age (

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Effect of vessel size on creation of hepatic radiofrequency lesions in pigs: assessment of the "heat sink" effect.

Charles Lassman, Steven Raman, Michael Wang … (2001)

The effect of vessels and their size on radiofrequency lesion creation in the liver was evaluated with respect to potential for vascular injury and perfusion-mediated "heat sink" effect. Radiofrequency lesions targeted to tissue adjacent to a variety of vessels were created in vivo in the liver of 10 Yorkshire pigs. Postablation contrast-enhanced CT and then histopathologic analysis of the vessels and lesions were performed after sacrifice of the pigs. Degree of vascular injury and viability of perivascular hepatocytes were recorded and tabulated according to vessel size for both CT and histologic data sets. At CT, 42 (95%) of 44 veins greater than 3 mm remained patent, and four (20%) of 20 veins less than 3 mm were occluded. Heat sink effect, indicated by invagination of enhancing tissue between vessel and radiofrequency lesion, was observed in 32 (73%) of 44 veins greater than 3 mm and in zero of 20 veins less than 3 mm. On histopathology, 111 (100%) of 111 vessels less than 3 mm showed at least partial vessel wall injury, characterized by endothelial cell necrosis and luminal thrombus. In 24 vessels greater than 3 mm, the extent of vessel wall injury decreased with increasing vessel diameter. Viable perivascular tissue indicative of heat sink effect was identified in 12 of 24 veins greater than 3 mm, increasing to seven of seven veins greater than 5 mm. None of 96 vessels less than 2 mm and three of 111 vessels less than 3 mm showed any heat sink effect. There appears to be a narrow transition zone for hepatic vessels at 2-4 mm, beyond which the heat sink effect was seen consistently and substantial vascular injury was rare.

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Comparing the outcomes of radiofrequency ablation and surgery in patients with a single small hepatocellular carcinoma and well-preserved hepatic function.

Kwang Cheol Koh, Jae-Won Joh, M. Choi … (2005)

To compare the efficacy of radiofrequency ablation (RFA) and surgical resection in a group of patients with a Child-Pugh score of 5 and a single HCC less than 4 cm in diameter. Radiofrequency ablation (RFA) has become a popular method for treatment of hepatocellular carcinoma (HCC) and has been applied as an alternative primary therapy to surgical resection. We compared outcomes for 148 patients treated with RFA (n = 55) and those treated surgically (n = 93). The rate of local recurrence among patients in the RFA group was significantly higher than in the surgery group (P = 0.005), while the incidence of remote recurrence was similar between the two groups (P = 0.30). The cumulative 1- and 3-year overall survival rates (P = 0.24) and the cumulative 1- and 3-year recurrence-free survival rates (P = 0.54) were not significantly different between the two groups. Despite a higher rate of local recurrence, RFA was found to be as effective as surgical resection for the treatment of single small HCC in patients with well-preserved liver function, in terms of the incidence of remote recurrence and the patients' likelihood of achieving overall and/or recurrence-free survival.

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Author and article information

Journal

Journal ID (nlm-ta): Korean J Radiol

Journal ID (publisher-id): KJR

Title: Korean Journal of Radiology

Publisher: The Korean Society of Radiology

ISSN (Print): 1229-6929

ISSN (Electronic): 2005-8330

Publication date (Print): Jan-Feb 2009

Publication date (Electronic): 05 February 2009

Volume: 10

Issue: 1

Pages: 43-50

Affiliations

Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sunkyunkwan University School of Medicine, Seoul 135-710, Korea.

Author notes

Address reprint requests to: Hyunchul Rhim, MD, Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Irwon-dong, Gangnam-gu, Seoul 135-710, Korea. Tel. (822) 3410-0908, Fax. (822) 3410-2559, rhimhc@ 123456skku.edu

Article

DOI: 10.3348/kjr.2009.10.1.43

PMC ID: 2647166

PubMed ID: 19182502

SO-VID: 16bb671b-ec4a-4bee-8532-89b129793dfe

License:

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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

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Abstract

Objective

Materials and Methods

Results

Conclusion

Related collections

Probing cerebral hemodynamics with BOLD fMRI

Most cited references 17

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.

Effect of vessel size on creation of hepatic radiofrequency lesions in pigs: assessment of the "heat sink" effect.

Comparing the outcomes of radiofrequency ablation and surgery in patients with a single small hepatocellular carcinoma and well-preserved hepatic function.

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