Photoacoustic imaging in biomedicine

TLDR

Photoacoustic imaging combines optical excitation with ultrasonic detection to provide high‑contrast, high‑resolution images of organs such as breast and brain. This review surveys the rapidly expanding field of photoacoustic imaging for biomedical applications. The article describes depth‑profiling, focused‑transducer tomography, acoustic‑lens image formation, and especially computed tomography with reconstruction algorithms and recent experimental advances. It highlights promising applications including skin and superficial organ tomography, near‑infrared breast cancer detection, and small‑animal imaging that offer deeper penetration, higher absorption contrast, and superior resolution compared to conventional optical methods.

Abstract

Photoacoustic imaging (also called optoacoustic or thermoacoustic imaging) has the potential to image animal or human organs, such as the breast and the brain, with simultaneous high contrast and high spatial resolution. This article provides an overview of the rapidly expanding field of photoacoustic imaging for biomedical applications. Imaging techniques, including depth profiling in layered media, scanning tomography with focused ultrasonic transducers, image forming with an acoustic lens, and computed tomography with unfocused transducers, are introduced. Special emphasis is placed on computed tomography, including reconstruction algorithms, spatial resolution, and related recent experiments. Promising biomedical applications are discussed throughout the text, including (1) tomographic imaging of the skin and other superficial organs by laser-induced photoacoustic microscopy, which offers the critical advantages, over current high-resolution optical imaging modalities, of deeper imaging depth and higher absorption contrasts, (2) breast cancer detection by near-infrared light or radio-frequency–wave-induced photoacoustic imaging, which has important potential for early detection, and (3) small animal imaging by laser-induced photoacoustic imaging, which measures unique optical absorption contrasts related to important biochemical information and provides better resolution in deep tissues than optical imaging.