Euromedim 2006 :1st European Conference on Molecular Imaging Technology

Method to localize a fluorescent inclusion in a turbid medium using time-resolved systems

11 May 2006, 14:00

1h

Palais du Pharo, Marseille

poster • Biomedical perspectives and technical challenges for morpho-functional imaging (multimodality : PET/CT,SPECT/CT,PET/MRI,SPECT/MRI ...) Poster session : Imaging systems, Molecular Imaging

Speaker

Dr Anabela da Silva (Cea-Leti Recherche Technologique)

Description

Optical fluorescent tomography can provide information about the spatial distribution, the lifetime and the concentration of specific fluorescently-labeled cell markers, inserted in highly scattering biological media. 3D fluorescent optical tomography systems are currently developed either with continuous wave, or in the frequency domain or in the time domain. The latter is the one which contains the richest information for a signal obtained from a single source-detector. A method to solve of the inverse problem is to extract some parameters from the whole temporal curve and to reconstruct the problem from these parameters. The aim of this work is to present an analytical approach using the mean time of the temporal signal to determine the position of a fluorescent inclusion in a turbid medium. We tested our method on optical phantoms on two experimental systems, a Time Correlated Single Photon Counting and a gated CCD camera. Light propagation is assumed to satisfy time-dependent diffusion equation. Analytical solutions describing the fluorophore response are expressed under several approximations. The general solution for fluorescence is the double convolution of the solution at the excitation wavelength for the propagation from the source to the inclusion by the fluorescence decay lifetime and then by the solution at the emission wavelength for the propagation from the inclusion to the detector. Analytical expression for the moment is obtained from derivations of expressions of the photon density in the frequency domain. Because they connect localization of the inclusion with the source-detector positions and optical properties of the medium, we can recover the localization of the inclusion from a set of experimental acquisitions.