Improved coagulation with saline solution pretreatment during radiofrequency tumor ablation in a canine model.

Abstract

PURPOSE:

To determine whether pretreatment with local NaCl injection can increase radiofrequency (RF)-induced coagulation in a large animal model.

MATERIAL AND METHODS:

Multiple canine venereal sarcomas (n = 25) were implanted subcutaneously in eight mildly immunosuppressed dogs (25 mg/kg cyclosporin A twice daily). Tumors were incubated for 8-12 weeks to a diameter of 4.2-6.3 cm (5.1 cm +/- 0.7). Internally cooled RF ablation (1-cm tip; 12 min; pulsed technique; 2,000-mA maximum) was performed. Tumors were pretreated with 6 mL of 18%, 24%, or 36% NaCl injected intratumorally under direct ultrasound guidance after RF electrode insertion, and this treatment was compared to RF treatment without NaCl injection and to 36% NaCl injection without RF ablation. Impedance measurements and remote thermometry were performed. These measurements and resultant coagulation were compared.

RESULTS:

Significantly greater RF heating (73 degrees C +/- 11 degrees C at 20 mm) was observed when the tumors were treated with 24% or 36% NaCl pretreatment, compared to the 47 degrees C +/- 5 degrees C observed when 18% or no NaCl was injected (P <.02). In the 36% NaCl group, the entire tumor (5.2 cm +/- 0.8 diameter) was completely ablated in every case, with coagulation extending several centimeters into the surrounding tissues. By comparison, control tumors (without NaCl injection) contained coagulation measuring 3.1 cm +/- 0.2, surrounded by viable, well-perfused tumor (P <.01), and 36% NaCl alone produced 2.7 cm +/- 0.6 of patchy necrosis.

CONCLUSIONS:

Pretreatment with intratumoral injection of small volumes of highly concentrated NaCl markedly increases RF heating and coagulation in a large animal tumor model. The complete destruction of tumors 5 cm in diameter or larger suggests that this substantial increase may be achieved for tumor ablation in clinical practice.

• Authors: Muneeb Ahmed, S Melvyn Lobo, Joseph Weinstein, Jonathan B Kruskal, G Scott Gazelle, Elkan F Halpern, S Karim Afzal, Robert E Lenkinski, S Nahum Goldberg
• Journal: Journal of vascular and interventional radiology : JVIR (J Vasc Interv Radiol) Vol. 13 Issue 7 Pg. 717-24 (Jul 2002) ISSN: 1051-0443 [Print] United States
• PMID: 12119331 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Saline Solution, Hypertonic

Topics

• Animals
• Catheter Ablation
• Dogs
• Electric Conductivity
• Hemostatic Techniques (instrumentation)
• Necrosis
• Regression Analysis
• Saline Solution, Hypertonic (pharmacology)
• Sarcoma (surgery)
• Venereal Tumors, Veterinary (surgery)