Noninvasive photoacoustic imaging of the thoracic cavity and the kidney in small and large animals

The internal organs of rats and rabbits were clearly imaged noninvasively using a deeply penetrating reflection-mode photoacoustic imaging system. This imaging system had previously been found to provide an imaging depth limit of ∼38 mm. In the thoracic cavity, major blood vessels connecting to the heart were imaged, and the right atrium was imaged as deeply as ∼8 mm. In the abdominal cavities, the kidney and vena cava inferior were also imaged in situ. The vena cava inferior ∼13.7 mm deep was imaged. The kidney of a New Zealand white rabbit was also imaged. This study shows the deep internal organ imaging capability of the system in animals. This technology can potentially be used to study tumors in internal organs, and be adapted to clinical diagnosis.