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Radio frequency (RF) ablation

Radio-frequency (RF) ablation is a minimally invasive procedure that has the potential for widespread use in hepatic cancer therapy. This RF energy generates heat, which destroys the tumor. Temperatures in the range of 50-600oC can start the process of denaturization in minutes. Treatment sessions are generally 10-30 min in duration and produce spherical necrotic regions that are 3-5.5 cm in diameter. Accurate mathematical models are valuable for predicting the temperature rise obtained during RF ablation, thereby enhancing the likelihood of tumor denaturization with minimal damage to surrounding tissue. Previous numerical research have used the Pennes bio-heat equation to model the heat transfer in the tissue domain. In the Pennes approach, heat transfer due to blood flow is modeled using a non-directional lumped heat sink and it does not accurately model the convective effect of blood flow near a large vessel. This work aims to provide an alternate to the Pennes equation by treating the perfusion in the tissue with a statistical approach i.e. as a porous medium. The vascular geometry is represented realistically by reconstructing the arterial geometry from MRI images of a porcine liver.

        Figure 1a shows the 3D geometry obtained from MRI images using image reconstruction. Figure 1b shows the reconstructed geometry in an isometric view. Figure 2 shows the speed and temperature contour plots for different arterial velocities. Increasing the blood flow rate from no flow to hyperemic flow (velocity = 41.4 cm/s) not only reduced the maximum temperature rise but also shifted the location of the maximum temperature rise. While the presence of blood perfusion is responsible for the reduction in maximum temperature rise, the large blood vessel is responsible for the shift in the location of the maximum temperature from the center. Thus both blood perfusion in microvessels and proximity of blood vessels influence the temperature rise.

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by zopeown last modified 2016-08-04 20:06