Oxygen-sensitive fluorophore-enhanced diffuse optical NIR spectroscopic imaging

Analysis of hypoxia plays an important role in cancer staging, understanding treatment resistance, diagnosis and treatment planning. Enhancing sensitivity to changes in oxygen concentration in deep tissue with continuous wave functional near infrared system (CW fNIRS) is highly desirable. CW fNIRS extract meaningful information based on temporal changes during the imaging segment. We propose a combination of CW fNIRS and oxygen-sensitive fluorophores to enhance the sensitivity to oxygen concentrations for cancer staging and diagnostics. We present a physics model for this novel system along with some preliminary experiments and simulations. The preliminary model includes an oxygen-sensitive fluorophore which, after excitation, fluoresces at 850nm whose gain is determined by the absence of oxygen. In addition to oxygen-sensitive fluorophore, with its fluorescence-quenching properties, photon count or intensity is amplified as a function of oxygen concentration. Alternatively, it can be proposed that fluorophore addition reduces the ‘optical impedance’, and eventually increases the photon count. We show preliminary simulations to depict the validity of the model.