Korean J Radiol.  2004 Mar;5(1):31-38. 10.3348/kjr.2004.5.1.31.

Combined Radiofrequency Ablation and Acetic Acid Hypertonic Saline Solution Instillation: An In Vivo Study of Rabbit Liver

• Lee JM
• Kim YK
• Kim SW
• Han JK
• Kim SH
• Choi BI

• KMID: 1066243
• DOI: http://doi.org/10.3348/kjr.2004.5.1.31

Abstract

OBJECTIVE
We wanted to determine whether combined radiofrequency ablation (RFA) and acetic acid-hypertonic saline solution (AHS) instillation can increase the extent of thermally mediated coagulation in in vivo rabbit liver tissue. We also wished to determine the optimal concentration of the solution in order to maximize its effect on extent of the RFA-induced coagulation. MAERIALS AND METHODS: Forty thermal ablation zones were produced in 40 rabbits by using a 17-gauge internally cooled electrode with a 1-cm active tip under ultrasound guidance. The rabbits were assigned to one of four groups: group A: RFA alone (n=10) ; group B: RFA with 50% AHS instillation (n=10) ; group C: RFA with 25% AHS instillation (n=10) ; group D: RFA with 15% AHS instillation (n=10). A range of acetic acid concentrations diluted in 36% NaCl to a total volume of 1 mL were instilled into the liver before RFA. The RF energy (30 W) was applied for three minutes. After RFA, in each group, the maximum diameters of the thermal ablation zones in the gross specimens were compared. Technical success and the complications that arose were evaluated by CT and on the basis of autopsy findings. RESULTS: All procedures are technically successful. There were six procedure-related complications (6/40; 15%) : two localized perihepatic hematomas and four chemical peritonitis. The incidence of chemical peritonitis was highest for group B with the 50% AHS solution instillation (30%). With instillation of 15% AHS solution, a marked decrease of tissue impedance (24.5+/-15.6 omega) and an increase of current (250 mA) occurred as compared to RFA alone. With instillation of the solutions before RFA (group B, C and D), this produced a greater mean diameter of coagulation necrosis than the diameters for rabbits not instilled with the solution (group A) (p < 0.05). However, there was no significant difference between group B, C, and D. CONCLUSION: Combined AHS instillation and RFA can increase the dimension of coagulation necrosis in the liver with a single application. A low concentration of AHS (15%) showed similar effects in increasing the extent of RF-induced coagulation, but there were less side effects as compared to the high concentration of AHS.

Keyword

Liver interventional procedures; Experimental study; Radiofrequency (RF) ablation

MeSH Terms

Acetic Acid/*administration & dosage
Animals
*Catheter Ablation
Combined Modality Therapy
Instillation, Drug
Liver/*drug effects/pathology/*surgery
Liver Neoplasms/drug therapy/surgery
Necrosis
Rabbits
Saline Solution, Hypertonic/*administration & dosage

Figure

• 

  Fig. 1 Cut Sections of gross specimens in the four groups. In groups B, C, and D, the combined radiofrequency ablations with instillation of the acetic acid-hypertonic saline solutions produced greater ablation zones than that does radiofrequency alone (group A). A. Gross specimen of a group A (radiofrequency ablation only) rabbit shows a round pale-discolored area (arrow) in the liver. B. Gross specimen of a group B (radiofrequency ablation with 50% acetic acid instillation) rabbit shows an oval shaped discolored coagulation zone (arrows) and thrombosis (arrowheads) of small vessels within the zone. C. Gross specimen of a group C (radiofrequency ablation with 25% acetic acid instillation) rabbit shows greater area of the ablation zone (arrow) than those of groups A (A) and B (B). D. Gross specimen of a group D (radiofrequency ablation with 15% acetic acid instillation) rabbit shows a similar appearance with the ablation zone to group C. Note that the thrombosis of small vessels (arrowheads) are seen in the coagulation area (arrow).

• 

  Fig. 2 Radiofrequency ablation with 25% acetic acid-hypertonic saline in a group C rabbit. A. At post-procedural CT scanning, a 25-mm diameter, oval-shaped perfusion defect (arrow) is seen. Note the gas bubbles (arrowheads) in vessels within the ablation zone. B. Gross specimen shows that the liver contains a white-brown colored coagulation zone (arrow) with an irregular margin. Note the thrombosis of hepatic vessels (arrowheads) within the coagulation area. C. Microscopic image (original magnification, ×200; hematoxylin-eosin staining) shows a typical coagulation necrosis (N) of the ablated ablation zones, which is surrounded by fibroid tissue (arrows) and normal hepatocytes (L).

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