Monitoring of tissue heating with medium intensity focused ultrasound via four dimensional optoacoustic tomography

Medium intensity focused ultrasound (MIFU) holds promise in important clinical applications. Generally, the aim in MIFU is to stimulate physiological mechanisms that reinforce healing responses, avoiding reaching temperatures that can cause permanent tissue damage. The outcome of interventions is then strongly affected by the temperature distribution in the treated region, and accurate monitoring represents a significant clinical need. In this work, we showcase the capacities of 4D optoacoustic imaging to monitor tissue heating during MIFU. The proposed method allows localizing the ultrasound focus, estimating the peak temperature and measuring the size of the heat-affected volume. Calibration experiments in a tissue-mimicking phantom demonstrate that the optoacoustically-estimated temperature accurately matches thermocouple readings. The good performance of the suggested approach in real tissues is further showcased in experiments with bovine muscle samples.