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

Vascular imaging is critical for understanding human health and disease. Most established non-contact and label-free optical techniques capture predominantly structural information about vasculature. However, in many pathologies, functional changes often precede visible morphological changes. This limits the ability of established modalities to prevent negative patient outcomes. In this study, a new in vivo Photon Absorption Remote Sensing (PARS) microscope is proposed. PARS enables the label-free non-contact structural and functional imaging of vascular structures and their microenvironment. PARS aims to capture the dominant light matter interactions surrounding an absorption event including both non-radiative and radiative relaxation. System performance is demonstrated through wide field of view in vivo imaging of vascular contrast in both mouse ear and chicken embryo. Additionally, video rate imaging of chicken embryo capillaries shows first feasibility for blood flow measurement using PARS. This work represents a promising step for vascular imaging techniques where there is significant demand for a method of non-contact label-free functional imaging.