Towards real-time monitoring of pulsed microwave ablation using thermoacoustic signals: A study of signal characteristics as a function of salinity

Tracking the characteristics of microwave-induced thermoacoustic (TA) signals is an emerging method for realtime monitoring of microwave ablation (MWA) performed with microsecond-duration microwave pulses. Extensive understanding of how tissue properties impact TA signal characteristics is necessary to enable the effective use of TA signals to monitor the evolution of an ablation zone. In this study, we investigate the impact of salinity content in water on TA signal characteristics that are generated as a result of pulsed microwave absorption. Experimentally measured TA signals are compared to computed TA signals using known salinity-dependent dielectric, thermal, and acoustic properties in a multi-physics simulation model. The predicted and observed trends with saline content are in agreement, and demonstrate the potential for monitoring a changing tissue environment during microwave heating by exploiting the thermoacoustic effect.