Evaluation method of ex vivo porcine liver reduced scattering coefficient during microwave ablation based on temperature.

The principle of microwave ablation (MWA) is to cause irreversible damage (protein coagulation, necrosis, etc.) to tumor cells at a certain temperature by heating, thereby destroying the tumor. We have long used functional near-infrared spectroscopy (fNIRs) to monitor clinical thermal ablation efficacy. After a lot of experimental verification, it can be found that there is a clear correlation between the reduced scattering coefficient and the degree of tissue damage. During the MWA process, the reduced scattering coefficient has a stable change. Therefore, both temperature (T) and reduced scattering coefficient ( ${\mu }_s^{\text{'}}$ ) are related to the thermal damage of the tissue. This paper mainly studies the changing law of T and ${\mu }_s^{\text{'}}$ during MWA and establishes a relationship model. The two-parameter simultaneous acquisition system was designed and used to obtain the T and ${\mu }_s^{\text{'}}$ of the ex vivo porcine liver during MWA. The correlation model between T and ${\mu }_s^{\text{'}}$ is established, enabling the quantitative estimation of ${\mu }_s^{\text{'}}$ of porcine liver based on T. The maximum and the minimum relative errors of ${\mu }_s^{\text{'}}$ are 79.01 and 0.39%, respectively. Through the electromagnetic simulation of the temperature field during MWA, 2D and 3D fields of reduced scattering coefficient can also be obtained using this correlation model. This study contributes to realize the preoperative simulation of the optical parameter field of microwave ablation and provide 2D/3D therapeutic effect for clinic.