Fluorescence lifetime estimation of multiple near-infrared dyes in mice

Abstract

In order to precisely recover fluorescence lifetimes from bulk tissues, one needs to employ complex light propagation models (e.g., the radiative transfer equation or a simpler yet consistent approximation, the diffusion equation) requiring knowledge of the tissue optical properties. This can be computationally expensive and therefore not practical in many applications. We present a novel method to estimate the fluorescence lifetimes of multiple fluorophores embedded in mice. By assuming that the photon diffusion does not significantly change the fluorescence decay slope, the light propagation is simply modeled as a time-delay during lifetime estimation. Applications of this approach are demonstrated by simulation, phantom data, and in vivo experiments.

Quantitative in vivo imaging of the lung using time-domain fluorescence measurements

“…Through the use of time-resolved measurement we are also able to recover lifetime information. In Figure 3 (b), we show the fluorescence lifetime image obtained using a proprietary algorithm [25] . Since the lifetime in the lung region is quite different from that of the stomach region, by applying lifetime gating, the autofluorescence from the food and tissue is suppressed, as shown in Figure 3 (c).…”

Background-Free In vivo Time Domain Optical Molecular Imaging Using Colloidal Quantum Dots

“…Lifetime can be used to differentiate fluorescence photons from different reporters and/or tissue autofluorescence . Lifetime can also be used to differentiate a reporter being in bound or unbound states. , Second, for certain fluorescent reporters, their lifetime is sensitive to their micro biological environment, such as pH, ,− Ca+, oxygen concentration, etc. In these cases, lifetime can be used to sense the micro environmental condition of neighboring tissues that are important for cancer research.…”

Characterization of natural fluorescence in mice

“…These parameters are unknown and trying to derive them by some fitting techniques is a thorny problem. See for example [23] exposing the case of fitting technique parameters for 2 dominant exogenous fluorophores.…”

“…The patterns are defined using a similar technique of classification to the one used in first section but applied only to the falling tail of a TPSF. It is well known that the way a TPSF decreases over time depends mainly on the composition of the fluorophore agents [23]. The question of representativeness of these model patterns is addressed through the examination of the error between them and the TPSF's they are supposed to represent.…”