Radiofrequency ablation (RFA) is a technique by which deposition of electromagnetic energy is used to thermally heat tissues. In addition, incomplete treatment with heat-based therapy alone may sometimes occur. It has been used widely in Taiwan for all variety of clinical treating modalities. To improve the efficacy of thermal therapies, many attempts have been used by modifying the tumor’s underlying physiologic characteristics. The objective of this study is to determine whether fluid saline injection during radiofrequency ablation (RFA) can increase the coagulation area and how parameters of both electrical conductivity and blood perfusion rate would impact on thermal lesion formation. Although the heat generated by this high-frequency current arises in all the conducting tissue pathways, high temperature only develops in tissues near the electrode, where the current density is high. Barely any heat arises in tissues further from the electrode because of the fall in current density and the cooling (or radiator) effect of blood flow. Continuous saline infusion is assumed at several locations to investigate the current density and temperature reaction. A simple two dimension (2D) geometry was used to illustrate electrical current pathways and temperature field. Finite-element numerical simulations are performed to solve the Laplace equation of the electric field calculation and Pennes bio-heat transfer equation of calculation temperature field. Results showed that injected saline regions could raise higher temperatures due to increasing electrical conductivity and thus extend the thermal lesion margins. Reversely, the blood perfusion rate which acted as heat sink effect could reduce the maximum temperature at squares.
Journal of Medical and Biological Engineering 38(6), p.880-888