Fluorescence lifetime imaging system for in vivo studies.
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.
Hassan
Moinuddin
M
Laboratory of Integrative and Medical Biophysics, National Institute of Child Health and Human Development, National Institute of Health, Bethesda, MD 20892, USA. hassanm@mail.nih.gov
Riley
Jason
J
Chernomordik
Victor
V
Smith
Paul
P
Pursley
Randall
R
Lee
Sang Bong
SB
Capala
Jacek
J
Gandjbakhche
Amir H
AH
D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism; D061067:Antibodies, Monoclonal, Humanized; D045744:Cell Line, Tumor; D004952:Esters / Q000378:metabolism; D005260:Female; D005456:Fluorescent Dyes / Q000032:analysis*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008325:Mammary Neoplasms, Experimental / Q000473:pathology*; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D019047:Phantoms, Imaging; D012117:Resins, Synthetic / Q000378:metabolism; D013388:Succinimides; D013997:Time Factors; D000068878:Trastuzumab
C502599:Alexa Fluor 750; D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D004952:Esters; D005456:Fluorescent Dyes; D012117:Resins, Synthetic; D013388:Succinimides; C010102:delrin; D000068878:Trastuzumab
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