Thermoacoustic signals generated from pulsed microwave ablation in liver tissue

Microwave-induced thermoacoustic signals are generated when pulsed microwave energy is absorbed by tissue. Thermoacoustic signals contain information about the electromagnetic, thermal, and acoustic material properties of the tissue. Thus, we propose using microwave-induced thermoacoustic signals to monitor microwave ablation, a thermal therapy used to heat and kill malignant tissue, in real-time. Conventional microwave-induced thermoacoustic signals are excited using an external waveguide. Our approach excites thermoacoustic signals via pulsed microwave energy delivered by the already present interstitial microwave ablation antenna. In this talk, we will present the experimental investigation of the evolution of microwave-induced thermoacoustic signals generated during microwave ablation in bovine liver tissue. Pulsed microwave energy was delivered via a narrow-diameter coaxial ablation antenna to simultaneously ablate tissue and excite thermoacoustic signals. Trials were conducted in room-temperature fresh liver tissue as well as room-temperature boiled liver tissue to investigate the influence of ablative temperature rise and tissue coagulation on thermoacoustic signals. Our experimental results show thermoacoustic signal characteristics change throughout the course of microwave ablation that could potentially be used for monitoring the microwave ablation process.