Towards Real-Time Monitoring of Thermal Ablation Lesions in Liver Using Microwave Imaging

Minimally invasive ablative therapies have been used extensively to treat hepatic tumors in patients where surgical resections are not needed. Besides electroporation, ablation therapies induce extreme temperatures, i.e., hypothermia or hyperthermia, to cause irreversible damage to the tissue cells. The lesion volume created as a result depends on the temperature gradient in the tissue. Accurate and sensitive temperature monitoring is critical to optimize the treatment and reduce the risk of complications and extrahepatic injury. This study presents an approach to assess the tissue temperatures non-invasively using microwave imaging (MWI). A cross-section of a liver phantom is used for microwave imaging electromagnetic simulation at 915 MHz. Dielectric properties of porcine liver tissue at 915 MHz and varying temperatures are gathered from the literature. Point sources placed around the phantom model act as transmitters and receivers. Distorted Born Iterative Method (DBIM) was used to reconstruct the relative permittivity that is mapped to the temperature field and compared. The mapped temperature field from the reconstructed dielectric parameters resembles the temperature field used to create the phantom model demonstrating the feasibility of using MWI for the non-invasive assessment of liver tissue temperatures for ablative therapies