Non-Contact Optical Spectroscopy for Metabolic and Vascular Characterizations of Orthotopic Tongue Cancer Models in Vivo

Most tissue optical spectroscopy platforms use a fiber probe for light delivery and collection, while the inconsistent probe-sample contact could induce significant distortions in the measured optical signals, which consequently bring analysis errors. Moreover, it will be practically difficult to use a fiber probe for measurements in some cases such as oral cancer investigations using small animal models. To address the critical challenge, we report a portable, lens-based, optical spectroscopy device capable of quantifying key vascular and metabolic parameters <i>in vivo</i> without probe-sample contact. We combined lenses based diffuse reflectance and fluorescence spectroscopy into one portable platform to enable multi-parametric functional characterizations of orthotopic tongue cancer models <i>in vivo</i>. We also implemented easy-to-use spectroscopic algorithms with the system for rapid quantification of the key metabolic and vascular parameters on biological tissue models. We then demonstrated our non-contact optical spectroscopy on tissue-mimicking phantoms and <i>in vivo</i> mouse tongue tumor models. Our phantom and <i>in vivo</i> animal studies showed that our non-contact optical spectroscopy, along with spectroscopic algorithms, could quantify the major metabolic and vascular parameters on <i>in vivo</i> tongue tumors with high accuracy. We also captured the diverse metabolic and vascular phenotypes of tongue tumors with different radiation sensitivity. Our new optical spectroscopy implemented with easy-to-use spectroscopic algorithms will provide a non-contact way for rapid and systematic characterizations of biological tissue metabolism and vascular microenvironment <i>in vivo</i>, which may significantly advance head and neck cancer research in the future.