Imaging (NIRI) and quantitation (NIRS) in tissue using time-resolved spectrophotometry: the impact of statistically and dynamically variable optical path lengths

摘要

Abstract: Near-infrared spectroscopy (NIRS) and near-infrared optical imaging (NIRI) are two medical techniques under development, respectively offering the ability to use light to noninvasively quantitate metabolite concentration and to image structure within the human body. Due to the dual effects of scattering and absorbance, quantitative measurement using NIRS and reconstruction of deep-tissue structure using NIRI have been problematic. Significant advances have occurred, however, over the past few years that have brought these measurements closer to reality. In this paper, we present several of the areas in which our laboratory has made progress, and discuss the relevance of these contributions in the light of work by other laboratories. With regard to NIR spectroscopy, it now appears both practical and necessary to take into account the length of the paths taken by light in order to derive deep-tissue estimates of pigment concentrations such as hemoglobin. With regard to NIR imaging, path corrected approaches offer improved resolution, and have been used successfully by our group and others to image phantoms, animals, and now humans. Different simplifications have been used in order to accomplish separately spectroscopy and imaging, but it is hoped that a common method will allow combination of the two techniques in order to achieve spatially resolved quantitative optical measurements. !84