A New Thermal Damage-Controlled Protocol for Thermal Ablation Modeled with Modified Porous Media-Based Bioheat Equation with Variable Porosity

Assunta Andreozzi,Marcello Iasiello,Giuseppe Peter Vanoli,Claudio Tucci,Luca Brunese

doi:10.3390/pr10020236

Assunta Andreozzi, Marcello Iasiello + Show 3 more

Open Access

https://doi.org/10.3390/pr10020236

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Journal: Processes	Publication Date: Jan 26, 2022
Citations: 1	License type: CC BY 4.0

Affiliation: University of Naples Federico II, University of Molise

Abstract

Thermal ablation of tumors is a minimally invasive technique more and more employed in cancer treatments. The main shortcomings of this technique are, on the one hand, the risk of an incomplete ablation, and on the other hand, the destruction of the surrounding healthy tissue. In this work, thermal ablation of a spherical hepatocellular carcinoma tumor (HCC) surrounded by healthy tissue is modeled. A modified porous media-based bioheat model is employed, including porosity variability from tumor core to healthy tissue, following experimental in vivo measures. Moreover, three different protocols are investigated: a constant heating protocol, a pulsating protocol, and a new developed damage-controlled protocol. The proposed damage-controlled protocol changes the heating source from constant to pulsating according to the thermal damage probability on the tumor rim. The equations are numerically solved by means of the commercial software COMSOL Multiphysics, and the outcomes show that the new proposed protocol is able to achieve the complete ablation in less time than the completely pulsating protocol, and to reach tissue temperature on the tumor rim 10 °C smaller than the constant protocol. These results are relevant to develop and improve different patient-based and automated protocols which can be embedded in medical devices’ software or in mobile applications, supporting medical staff with innovative technical solutions.

Highlights

Nowadays, thermal ablation of tumors is considered an effective technique for fighting cancer
Software included in medical devices such as generators are not able to predict accurately the power and duration needed to achieve the final ablation zones, probably because they are based on ex vivo measures and too simple bioheat models
Throughout the years, different bioheat models have been implemented [6,7] since Pennes’ equation [8]. This first bioheat equation is still widely used for its simplicity, but it is less accurate than other models due to its main shortcomings

Summary

Introduction

Thermal ablation of tumors is considered an effective technique for fighting cancer The interest in this technique is growing because of the advantages it involves compared to surgery, chemotherapy, and radiotherapy: it is a so called minimally invasive treatment which yields minor sides effects, shorter hospital stays, and costs [1,2,3]. This first bioheat equation is still widely used for its simplicity, but it is less accurate than other models due to its main shortcomings It does not consider the blood flow direction and it assumes the thermal equilibrium between tissue and venous blood. The employed numerical model is a modified porous media-based local thermal non-equilibrium bioheat model which considers the porosity variability between the core and rim of tumor and the surrounding healthy tissue. The aim is to develop new accurate and patient-based bioheat models and protocols in thermal ablation treatments, improving the current procedures and medical devices. In the future automated personalized protocols can be obtained, and the complete tumor ablation can be achieved according to specific patients’ and tumors’ characteristics

Mathematical Model

Numerical Solution and Validation

Validation of the Model

Results and Discussion