Radio-frequency Thermal Ablation With NaCl Solution Injection: Effect of Electrical Conductivity on Tissue Heating and Coagulation-Phantom and Porcine Liver Study

Radiology. 2001 Apr;219(1):157-65. doi: 10.1148/radiology.219.1.r01ap27157.

Abstract

Purpose: To characterize the effects of NaCl concentration on tissue electrical conductivity, radio-frequency (RF) deposition, and heating in phantoms and optimize adjunctive NaCl solution injection for RF ablation in an in vivo model.

Materials and methods: RF was applied for 12-15 minutes with internally cooled electrodes. For phantom experiments (n = 51), the NaCl concentration in standardized 5% agar was varied (0%-25.0%). A nonlinear simplex optimization strategy was then used in normal porcine liver (n = 44) to determine optimal pre-RF NaCl solution injection parameters (concentration, 0%-38.5%; volume, 0-25 mL). NaCl concentration and tissue conductivity were correlated with RF energy deposition, tissue heating, and induced coagulation.

Results: NaCl concentration had significant but nonlinear effects on electrical conductivity, RF deposition, and heating of agar phantoms (P<.01). Progressively greater heating was observed to 5.0% NaCl, with reduced temperatures at higher concentrations. For in vivo liver, NaCl solution volume and concentration significantly influenced both tissue heating and coagulation (P<.001). Maximum heating 20 mm from the electrode (102.9 degrees C +/- 4.3 [SD]) and coagulation (7.1 cm +/- 1.1) occurred with injection of 6 mL of 38.5% (saturated) NaCl solution.

Conclusion: Injection of NaCl solution before RF ablation can increase energy deposition, tissue heating, and induced coagulation, which will likely benefit clinical RF ablation. In normal well-perfused liver, maximum coagulation (7.0 cm) occurs with injection of small volumes of saturated NaCl solution.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Body Temperature Regulation / physiology
  • Dose-Response Relationship, Drug
  • Electric Conductivity
  • Female
  • Hyperthermia, Induced / instrumentation*
  • Liver / pathology
  • Liver / physiopathology*
  • Male
  • Saline Solution, Hypertonic / pharmacology*
  • Swine

Substances

  • Saline Solution, Hypertonic