title: Target-to-background enhancement in multispectral endoscopy with background autofluorescence mitigation for quantitative molecular imaging.
abstract: Fluorescence molecular imaging with exogenous probes improves specificity for the detection of diseased tissues by targeting unambiguous molecular signatures. Additionally, increased diagnostic sensitivity is expected with the application of multiple molecular probes. We developed a real-time multispectral fluorescence-reflectance scanning fiber endoscope (SFE) for wide-field molecular imaging of fluorescent dye-labeled molecular probes at nanomolar detection levels. Concurrent multichannel imaging with the wide-field SFE also allows for real-time mitigation of the background autofluorescence (AF) signal, especially when fluorescein, a U.S. Food and Drug Administration approved dye, is used as the target fluorophore. Quantitative tissue AF was measured for the ex vivo porcine esophagus and murine brain tissues across the visible and nearinfrared spectra. AF signals were then transferred to the unit of targeted fluorophore concentration to evaluate the SFE detection sensitivity for sodium fluorescein and cyanine. Next, we demonstrated a real-time AF mitigation algorithm on a tissue phantom, which featured molecular probe targeted cells of high-grade dysplasia on a substrate containing AF species. The target-to-background ratio was enhanced by more than one order of magnitude when applying the real-time AF mitigation algorithm. Furthermore, a quantitative estimate of the fluorescein photodegradation (photobleaching) rate was evaluated and shown to be insignificant under the illumination conditions of SFE. In summary, the multichannel laser-based flexible SFE has demonstrated the capability to provide sufficient detection sensitivity, image contrast, and quantitative target intensity information for detecting small precancerous lesions in vivo.
authors.affiliation: University of Washington, Department of Bioengineering, Seattle, Washington 98195, United States.
authors.forename: Chenying
authors.initials: C
authors.lastname: Yang
authors.affiliation: University of Washington, Department of Biology, Seattle, Washington 98195, United States.
authors.forename: Vivian W
authors.initials: VW
authors.lastname: Hou
authors.affiliation: Fred Hutchinson Cancer Research Center, Clinical Research Division, Seattle, Washington 98109, United States.
authors.forename: Emily J
authors.initials: EJ
authors.lastname: Girard
authors.affiliation: University of Washington, Department of Mechanical Engineering, Seattle, Washington 98195, United States.
authors.forename: Leonard Y
authors.initials: LY
authors.lastname: Nelson
authors.affiliation: University of Washington, Department of Mechanical Engineering, Seattle, Washington 98195, United States.
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Seibel
mesh_terms: D000818:Animals; D001471:Barrett Esophagus / Q000473:pathology; D001923:Brain Chemistry; D004724:Endoscopy / Q000379:methods*; D004947:Esophagus / Q000737:chemistry; D005260:Female; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008297:Male; D051379:Mice; D016513:Mice, SCID; D057054:Molecular Imaging / Q000379:methods*; D009374:Neoplasms, Experimental; D061848:Optical Imaging / Q000379:methods*; D019047:Phantoms, Imaging; D013552:Swine