FLAME: Macroscopic imaging with microscopic resolution. Optical biopsy of human skin

We introduce a compact, fast large area multiphoton exoscope (FLAME) system with enhanced molecular contrast for macroscopic imaging of human skin with microscopic resolution. A versatile imaging platform with multiple modes of operation for comprehensive analysis of live or resected thick human skin tissue, it produces 3D images that encompass sub-mm 2 to cm 2 scale areas of tissue within minutes. The FLAME imaging platform, which expands on a design recently introduced by our group, features deep learning, additional scanning hardware elements and time-resolved single photon counting detection to uniquely allow fast discrimination and 3D virtual staining of melanin. We demonstrate its performance and utility by fast ex vivo and in vivo imaging of human skin. With the ability to provide rapid access to depth resolved images of skin over cm 2 area and to generate 3D distribution maps of key sub-cellular skin components such as melanocytic dendrites and melanin, FLAME represents a promising imaging tool for enhancing diagnosis accuracy, guiding therapy and understanding skin biology.