Open AccessFluorescence Lifetime Imaging System for in Vivo Studies
Author(s) -
Hassan Mohabatkar,
Jason Riley,
Victor Chernomordik,
Paul D. Smith,
Randall Pursley,
Sang Bong Lee,
Jacek Capala,
Amir Gandjbakhche
Publication year - 2007
Publication title -
molecular imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.815
H-Index - 60
eISSN - 1536-0121
pISSN - 1535-3508
DOI - 10.2310/7290.2007.00019
Subject(s) - alexa fluor , fluorophore , fluorescence , in vivo , fluorescence lifetime imaging microscopy , imaging phantom , materials science , chemistry , biophysics , biomedical engineering , optics , physics , biology , medicine , microbiology and biotechnology
In this article, a fluorescence lifetime imaging system for small animals is presented. Data were collected by scanning a region of interest with a measurement head, a linear fiber array with fixed separations between a single source fiber and several detection fibers. The goal was to localize tumors and monitor their progression using specific fluorescent markers. We chose a near-infrared contrast agent, Alexa Fluor 750 (Invitrogen Corp., Carlsbad, CA). Preliminary results show that the fluorescence lifetime for this dye was sensitive to the immediate environment of the fluorophore (in particular, pH), making it a promising candidate for reporting physiologic changes around a fluorophore. To quantify the intrinsic lifetime of deeply embedded fluorophores, we performed phantom experiments to investigate the contribution of photon migration effects on observed lifetime by calculating the fluorescence intensity decay time. A previously proposed theoretical model of migration, based on random walk theory, is also substantiated by new experimental data. The developed experimental system has been used for in vivo mouse imaging with Alexa Fluor 750 contrast agent conjugated to tumor-specific antibodies (trastuzumab [Herceptin]). Three-dimensional mapping of the fluorescence lifetime indicates lower lifetime values in superficial breast cancer tumors in mice