Intrinsic fluorescence spectroscopy in turbid media: disentangling effectsof scattering and absorption

The fluorescence from a turbid medium such as biologic tissue contains info rmation about scattering and absorption, as well as the intrinsic fluoresce nce, i.e., the fluorescence from an optically thin sample of pure fluoropho res. The interplay of scattering and absorption can result in severe distor tion of the intrinsic spectral features. These distortions can be removed b y use of a photon-migration-based picture and information from simultaneous ly acquired fluorescence and reflectance spectra. We present experimental e vidence demonstrating the validity of such an approach for extracting the i ntrinsic fluorescence for a wide range of scatterer and absorber concentrat ions in tissue models, ex vivo and in vivo tissues. We show that variations in line shape and intensity in intrinsic tissue fluorescence are significa ntly reduced compared with the corresponding measured fluorescence. (C) 200 1 Optical Society of America.