Fluorescence attenuated by a thick scattering medium: Theory, simulations and experiments

Abstract

Fluorescence-based imaging has an enormous impact on our understanding of biological systems. However, in vivo fluorescence imaging is greatly influenced by tissue scattering. A better understanding of this dependence can improve the potential of noninvasive in vivo fluorescence imaging. In this article, we present a diffusion model, based on an existing master-slave model, of isotropic point sources imbedded in a scattering slab, representing fluorophores within a tissue. The model was compared with Monte Carlo simulations and measurements of a fluorescent slide measured through tissue-like phantoms with different reduced scattering coefficients (0.5-2.5 mm À1 ) and thicknesses (0.5-5 mm). Results show a good correlation between our suggested theory, simulations and experiments; while the fluorescence intensity decays as the slab's scattering and thickness increase, the decay rate decreases as the reduced scattering coefficient increases in a counterintuitive manner, suggesting fewer fluorescence artifacts from deep within the tissue in highly scattering media.

Multiplexed near infrared fluorescence lifetime imaging in turbid media

“…We established three core assumptions, strategically designed to streamline and expedite computation time. Selective photon consideration: the model accounts for emitted fluorescent photons only and disregards excitation photons, based on the results from our recent publication 22 . Temporal emission decay: The number of emitted photons into the tissue diminishes progressively based on a decay constant, intricately linked with the fluorophore’s lifetime.…”

“…In this study, we model the photons emitted by a fluorophore within a tissue 21 . Furthermore, we employ our recently introduced simplified MC model for the propagation of fluorescence photons in biological tissues 22 . In this model, we disregard excitation photons and treat the fluorophore as an isotropic light source within the tissue.…”

Time-gated Fluorescence Lifetime Imaging in the Near Infrared Regime; A Comprehensive Study Toward In Vivo Imaging

“…We present a new MC approach to study multiplexed FLI through tissue in the NIR regime. Our MC model is based on three main assumptions, that allowed us to simplify and shorten the computation time: (i) The model considers only the emitted fluorescent photons, and ignores the excitation photons (based on our recent publication 19 ). (ii) The number of photons emitted into the tissue decreases according to a relaxation constant, that correlates with the lifetime of the fluorophore.…”

“…This method is very time consuming, although shorter than the direct approach. In this work, we use a recently proposed simplified MC model for fluorescence photon propagation in biological tissue, in which we neglect the excitation photons and consider the fluorophore as an isotropic light source 19 (thus avoiding the need for the "method of images" 20 ). Despite these neglections, which reduce the simulation time by half, we show that the general behavior of simulation and experiments correlates well.…”

Locating Three-Dimensional Position of Deep-Seated SERS Phantom Lesions in Thick Tissues Using Tomographic Transmission Raman Spectroscopy

“…Locating specific objects inside a thick highly scattering medium remains a long-standing challenge in the field of materials science, medicine, and engineering. , For industrial applications, this capability can help to identify specific objects for customs identification, drug analysis, and so on. In medicine, it is particularly useful for locating lesions, such as tumors or lymph nodes, after specific targeting with contrast agents.…”