Label-Free Non-Contact Vascular Imaging using Photon Absorption Remote Sensing

Objective: Functional vascular imaging is a critical method for early detection and prevention of disease. Established non-contact vascular imaging techniques capture predominantly structural information. In this study, a novel non-contact label-free in vivo Photon Absorption Remote Sensing (PARS) microscope is developed for structural and functional vascular imaging. Methods: The presented in vivo PARS microscope captures the endogenous absorption of green (532nm) light to form a complete picture of vasculature and surrounding tissues. Imaging system repeatability is enhanced through robust transient absorption signal extraction, and state-of-the-art real-time alignment methods. Results: Detailed imaging of vascular structure is demonstrated through in vivo microscopy of two established animal models: mouse ear and chicken embryo. Preliminary functional contrast is realized through video rate imaging of red blood cell dynamics in the capillary networks of chicken embryos. Conclusion: The presented in vivo PARS microscope successfully captures detailed structural and functional vascular contrast. Significance: This innovative non-contact label-free imaging technique holds promise as a tool for preventative medical care, as functional change often precedes structural change.