Fluorescence lifetime imaging for deep-seated fluorophore in turbid medium

For correct identification of fluorophores in fluorescence lifetime imaging in vivo it is important to account for widening of fluorescent kinetics curve due to light scattering and absorption in turbid medium. This widening leads to the difference between real and measured lifetimes of a fluorescent agent. We studied this effect for media with different optical properties and lifetimes corresponding to those of real fluorophores applying Monte-Carlo simulation. We found that for the fluorophore depths up to 15 mm for reduced scattering coefficient varying from 0.15 to 4.8 mm -1 and absorption coefficient varying from 0.0025 to 0.08 mm -1 this difference is insignificant for long-lived fluorophores (typical fluorescent proteins), however, it should be taken into account for fluorophores with lifetimes of several hundred picoseconds. Results of numerical simulation are confirmed by the results of the model experiment.