Microwave temperature imaging with microwave ablation – phantom experiments

Purpose To perform a series of microwave ablation phantom heating experiments while monitoring the temperature with microwave tomography and to assess whether the heating patterns differ when the HeatSYNC gel is positioned close to the microwave ablation device.Materials and methods The heating proceeded over 10 minutes with a cooling period of 5 minutes afterwards. Data was acquired at 10 second intervals in 0.5 second snap shots. The images were reconstructed off-line using our fast, discrete dipole approximation-based algorithm. The study was repeated for the case with just the microwave ablation antenna embedded in an agar gel and afterwards in a similar gel but with two thin cylinders of HeatSYNCTM gel positioned next to the antenna. The HeatSYNCTM gel is a protein-based formulation that is designed to absorb electromagnetic energy. The gel is developed to enhance the performance of thermal ablation of large tumors. its high conductivity acts to direct more of the heating towards it and away from the opposite side of the ablation antenna. The purpose of the gel is to enable the technician to tailor the heating and ablation patterns to larger and specific tumor configurations.Results The results show good correlation between the recovered microwave images and the associated temperature rises. It also shows expected changes to the heating patterns for the case when the HeatSYNC gel is placed close to the microwave ablation device.Conclusions These pilot results demonstrate that the microwave imaging is capable of recovering accurate property distributions that reflect the heating patterns. It also shows that the HeatSYNCTM gel has the desired effect on the heating pattern and the results are consistent with previous simulation investigations.