Radio frequency (RF) tissue ablation is a minimally invasive treatment commonly used to destroy tumors or alleviate tissue blockages. The simulation of RF tissue ablation helps device designers predict the thermal and electric fields in the affected tissue.
There are, however, challenges in properly setting up the coupled multiphysics analysis and in determining realistic inputs to the model.
We developed a COMSOL Multiphysics model of an RF ablation problem involving a monopolar electrode targeting a tissue close to a blood vessel. We accounted for the electric and heat transfer fields in the tissue and blood as well as the blood flow. We predicted the temperature variation and the damage evolution in the tissue.
The animation in Figure 1 shows the temperature variation in the tissue and blood for a 20-second ablation procedure.
The images below show the model we developed and the temperature and flow streamlines in the blood. We then illustrated the sensitivity of the results to several parameters, including the placement of the electrodes, the variation of electrical and thermal conductivities with temperature, and the interface conditions between electrode and tissue.
We also have a procedure to evaluate the relevant parameters using experimental testing, numerical simulation of the additional tests, and inverse calibration.
Veryst also developed a simulation application or “app” based on the RF ablation model. The app (pictured below) enables individuals to run this simulation without being COMSOL Multiphysics experts and to analyze design variations or perform sensitivity studies.
For example, they can investigate what happens if the electrode is tilted or how tissue damage will be affected by changes in voltage or electrode cooling. They can also explore the effects of various changes to the tissue damage model.