Hybrid-scanning optical-resolution photoacoustic microscopy for in vivo vasculature imaging.

Recently developed optical-resolution photoacoustic microscopy (OR-PAM), which is based on the detection of optical absorption contrast, is complementary to other optical microscopy modalities such as optical confocal microscopy, optical coherence tomography, and multiphoton microscopy. A hybrid optical-mechanical scanning configuration increases the imaging speed of OR-PAM significantly, facilitating many demanding biomedical applications. With a high-pulse-repetition-rate laser, the hybrid-scanning OR-PAM can acquire one-dimensional depth-resolved images (A-lines) at 5 kHz and two-dimensional B-scan images containing 800 A-lines at 6.25 Hz. We demonstrated in vivo in a mouse three-dimensional imaging of the iris vasculature in 128 s for an 800x800x200 data set and of the ear vasculature in 256 s for an 800x1600x200 data set.