NIR-II fluorescence microscopic imaging of cortical vasculature in non-human primates

Abstract

Vasculature architecture in the brain can provide revealing information about mental and neurological function and disease. Fluorescence imaging in the second near-infrared (NIR-II) regime with less light scattering is a more promising method for detecting cortical vessels than traditional visible and NIR-I modes. Here, for the first time, we developed, NIR-II fluorescence microscopy capabilities for imaging brain vasculature in macaque monkey. The first is a wide-field microscope with high temporal resolution (25 frames/second) for measuring blood flow velocity and cardiac impulse period, and the second is a high spatial resolution (<10 m) confocal microscope producing three-dimensional maps of the cortical microvascular network ([~]500 m deep). Both were designed with flexibility to image various cortical locations on the head. Use of a clinically approved dye provided high brightness in NIR-II region. This comprises an important advance towards studies of neurovascular coupling, stroke, and other diseases relevant to neurovascular health in humans.