Abstract

Background

Radiofrequency ablation (RFA) represents a common type of thermal ablation for lung tumors. In order to improve RFA systems for lung tumors, extensive laboratory testing is required. Since human lung tumors are not available in adequate quantity and quality as a model system, animal tissue is commonly used. However, different electrical properties are often observed, making a comparison difficult. Therefore, new tissue surrogates are required.

Material and Methods

First, reference values for electrical impedance in different lung tumor types were collected in vivo (n=10) during routine RFA. Subsequently, several components were tested to develop a tissue-mimicking surrogate. For validation, RFA was performed in the surrogate by measuring the short and long axis for different ablation times.

Results

The mean impedance in lung tumors during RFA was 103.5±14.7? (adenocarcinoma: 109.2±13.9?, squamous cell carcinoma: 90.1±3.0?).

The optimized surrogate tissue model for lung tumor consisted of 68% agar solution, 23% egg yolk, 9% thermochromic ink and variable amounts of sodium chloride.

The mean impedance of the surrogate tissue was adjustable to the electrical properties of the tumor types ranging from 74.3±0.4? to 183.2±5.6? and was a function (y = -368.4x+175.2; R2=0.96; p<0.001) of sodium chloride concentration (between 0-0.3%). The surrogate tissue showed sufficient dimensional stability and revealed clear margins of color change after RFA.

Conclusion

The tissue-mimicking surrogate can be adapted to lung tumor with respect to its electrical properties. As the surrogate tissue allows a simple and cost-effective manufacturing, it is suitable for extensive laboratory testing of RFA systems for pulmonary ablation.