Fluorescence-enhanced absorption and lifetime imaging

Near-infrared biomedical optical imaging consists of imaging interior volumes on the basis of optical property cent rast from measurements conducted at the air-tissue interface. However, the ability to optically image or detect diseased tissue volumes located deep within tissues depends upon the contrast provided by differences iu absorption and scattering. The exogenous contrast offered by fluorescent contrast agents may be superior to that provided by nonfluorescing, light-absorbing compounds, when the optical measurements are conducted with frequency-domain techniques. However, the reconstruction of internal fluorescent properties of quantum efficiency and lifetime has been difficult, especially when the finite partitioning of fluorescent compounds takes place between normal and diseased tissues. Also, the correct absorption coefficient map is required for the successful reconstruction of lifetime. Herein we present a novel fluorescence-enhanced imaging algorithm for frequency-domain photon migration measurements conducted at the air-tissue interface. Similar to Born iterative image reconstruction techniques, fluorescence-enhanced imaging differs in that it utilizes measurements of generated fluorescent wave instead of scattered excitation wave. Using synthetic data sets, we demonstrate fluorescence-enhanced imaging using FDA approved fluorescent agent. Indocynine Green (ICG). Our results show the fluorescence-enhanced imaging algorithm works well up to 10:1 dye uptake ratio, and it is relatively insensitive to measurement noise. In addition, we present the lifetime reconstruction with a modified fluorescence-enhance imaging technique.