Thermoacoustic imaging: From single-element scanning to portable and array-based imaging

The microwave-induced thermoacoustic imaging (TAI) technology has both the advantages of high contrast of microwave imaging and high resolution of ultrasound imaging (UI), so it has carried out exploratory application research in various areas, such as the early detection of breast tumors and cerebrovascular diseases. However, the microwave generator used in the traditional TAI technology is huge and expensive, and the temporal resolution is also too low due to the single-element scanning mechanism. Thus, it is difficult to meet the needs of clinical applications. In this paper, the iterative process and the analysis of related application scenarios from single-element scanning to portable and array-based TAI, such as the miniaturized microwave generator, handheld antenna, multi-channel data acquisition, and UI/TAI dual-modality imaging, are reviewed, and the future trends of this technology are discussed. This review helps researchers in the field of TAI learn the technological development process and future trends. It also deepens clinicians’ understanding of TAI so as to put forward more application requirements.