Thermoacoustic endoscopy

In this study, we developed microwave-induced thermoacoustic endoscopy (TAE), which employs a high-repetition-rate pulsed microwave generator for external excitation and a side-view focused ultrasound transducer for internal acoustic detection. The system yields a lateral resolution of 1.5 mm and an axial resolution of 0.35 mm. The penetration depths of saline-containing tube (5% NaCl) and tumor lesions in biological tissues are 9 and 6 cm under current experimental conditions, respectively. To improve the signal-to-noise ratio (SNR) of the reconstructed image and eliminate the off-focus distortion of the transducer, we applied the synthetic aperture focusing technique (SAFT) and coherence weighting factor into the reconstruction algorithm. Additionally, we carried out in vivo rat experiments to evaluate clinical feasibility of this technique. We could clearly distinguish multiple tumor lesions embedded inside the rat abdomen from the surrounding normal tissues.