Microwave-induced thermoacoustic imaging (TAI) is a noninvasive modality based on the differences in microwave absorption of various biological tissues. TAI has been extensively researched in recent years, and several studies have revealed that TAI possesses advantages such as high resolution, high contrast, high imaging depth and fast imaging speed. In this paper, we reviewed the development of the TAI technique, its excitation source, data acquisition system and biomedical applications. It is believed that TAI has great potential applications in biomedical research and clinical study.

In situ image guidance is one of the key techniques for accurate diagnosis and treatment in clinical medicine. Conventional imaging techniques such as CT, MRI provide critical information for diagnosis and treatment planning, but are less practical due to either technical complexity or ionizing radiation-related safety. Microwave-pumped thermoacoustic imaging (MTAI) is a promising alternative to real-time bioimaging due to its deep imaging depth, high resolution and minimal biological hazards. More importantly, by mapping the distribution of microwave absorbers, this method can also provide a new perspective for noninvasively observing the anatomy and functional structure of the target. In this work, we introduce a concept of in situ MTAI guidance by combining MTAI and an accurate spatial definition of invasive apparatus used in potential procedures. By mounting tiny MTAI beacons on the apparatus, it is possible to accurately reconstruct the relative position of the device to the target tissue for either real time visual guidance or as the foundation for potential automated procedures. The image quality including its applicable depth and resolution, the accuracy of the device localization is analyzed and tested with simulated breast tumor to demonstrate the capacity of the proposed technique. With refined adaptation for potential applications, this technique may provide a novel approach for a broad range of medical and biological applications.

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Abstract：This article reports a real-time thermoacoustic imaging system for breast cancer screening.The experimental results show that it realizes the fast three-dimensional thermoacoustic imaging, therefore it has the potential to become a routine breast screening method.