Microwave Ablation Monitoring Using Thermoacoustic and Ultrasound Tomography.

Microwave ablation is an established minimally invasive technique that induces thermal necrosis in centimeter-scale tumors in organs such as the liver and kidney. However, the efficacy of clinical protocols is challenged by patient-specific and tissue-specific variations that may require personalized parameters to achieve optimal therapeutic outcomes. To address these limitations, we introduce an imaging technique employing modulated microwave signals that maintain peak and average powers comparable to those of existing clinical systems (~100-200 W). This modulation introduces time-varying tissue heating, generating detectable thermoacoustic signals that are used to reconstruct images proportional to the spatial heat deposition. When combined with thermal models of the tissue, we estimate the spatial temperature profile and ablation status over time. We validate this approach in ex vivo bovine liver compared against ultrasound tomography and tissue dissection. This approach may enable closed-loop monitoring and adaptive control of ablation procedures to optimize lesion coverage while sparing surrounding healthy tissue.