This mouse brain was imaged in vivo without imaging agents using fast functional photoacoustic microsopy. The researchers used the hemoglobin in the red blood cells to provide contrast in the left image. Oxygen saturation levels in the hemoglobin in the same mouse brain define the cortical arteries and veins in the right image.

Credit: Junjie Yao and Lihong Wang, WUSTL

Photoacoustic imaging, based on a concept Alexander Graham Bell discovered in the 1880s, combines laser light and ultrasound. In this case, at a rate of 20 3-D images per second, scientists are able to study red blood cells in great detail.

Credit: Lidai Wang and Lihong Wang, WUSTL