RF Tissue Ablation Simulation

Technical Challenge

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.
 

Veryst Solution

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.

Temperature Animation
Figure 1. Animation showing temperature variation in tissue and
blood using monopolar electrode

 

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.

RF Schematic
Figure 2. Schematic of monopolar ablation problem (altered from actual device geometry)

We also have a procedure to evaluate the relevant parameters using experimental testing, numerical simulation of the additional tests, and inverse calibration.

RF Ablation and Streamlines
Figure 3. Temperature in the tissue and blood and flow streamlines in the blood

 

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.

RF Ablation App

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