Effects of modeled optical properties on recovered fluorophore concentration during image-guided fluorescence tomography

In fluorescence molecular tomography, optical measurements at the surface are used with diffusion theory modeling to reconstruct the maps of the fluorophore distribution in the tissue using an iterative error minimization algorithm. While normalizing the fluorescence signal with the excitation signal has been shown to correct for source and detector inconsistencies somewhat, this approach does not always correct for tissue heterogeneities and inaccuracies that are not matched by the forward diffusion model. Using computer simulations and an ultrasound-guided fluorescence tomography (FT) system designed for spatial mapping of Protoporphyrin IX (PpIX), the errors in fluorophore concentration recovery by assignment of incorrect optical properties are analyzed. Using simulations and experiments, white light spectroscopy was used to obtain more accurate tissue properties for forward diffusion model, prior to FT. Using white light spectroscopy the accuracy in FT values improved by 97% on average and the minimal detectable concentration of PpIX with the system was 0.025μg/ml.

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