Opportunities of optical and spectral technologies in intraoperative histopathology

Modern optical and spectral technologies represent powerful approaches for a molecular characterization of tissues enabling delineating pathological tissues but also a label-free grading and staging of tumors in terms of computerassisted histopathology. First, currently used tools for intraoperative tumor assessment are described. Next, the requirements for intraoperative tissue visualization from a medical and optical point of view are specified. Then, optical and spectral techniques are introduced that are already approved or close to being used in standard clinical practice for ex vivo and in vivo monitoring, and proof-of concept studies utilizing linear and nonlinear spectroscopy and imaging modalities are presented. Combining several spectroscopic mechanisms in multi-contrast approaches constitutes further advances. Modern artificial intelligence and deep learning concepts have emerged to analyze spectroscopic and imaging datasets and have contributed to the progress of each technique. Finally, an outlook for opportunities and prospects of clinical translation is given.