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Journal of Biomedical Optics • Open Access

Mathematical model to interpret localized reflectance spectra measured in the presence of a strong fluorescence marker

Paper Abstract

Quantification of multiple fluorescence markers during neurosurgery has the potential to provide complementary contrast mechanisms between normal and malignant tissues, and one potential combination involves fluorescein sodium (FS) and aminolevulinic acid-induced protoporphyrin IX (PpIX). We focus on the interpretation of reflectance spectra containing contributions from elastically scattered (reflected) photons as well as fluorescence emissions from a strong fluorophore (i.e., FS). A model-based approach to extract μa and μ′s in the presence of FS emission is validated in optical phantoms constructed with Intralipid (1% to 2% lipid) and whole blood (1% to 3% volume fraction), over a wide range of FS concentrations (0 to 1000  μg/ml). The results show that modeling reflectance as a combination of elastically scattered light and attenuation-corrected FS-based emission yielded more accurate tissue parameter estimates when compared with a nonmodified reflectance model, with reduced maximum errors for blood volume (22% versus 90%), microvascular saturation (21% versus 100%), and μ′s (13% versus 207%). Additionally, quantitative PpIX fluorescence sampled in the same phantom as FS showed significant differences depending on the reflectance model used to estimate optical properties (i.e., maximum error 29% versus 86%). These data represent a first step toward using quantitative optical spectroscopy to guide surgeries through simultaneous assessment of FS and PpIX.

Paper Details

Date Published: 1 February 2016
PDF: 8 pages
J. Biomed. Opt. 21(6) 061004 doi: 10.1117/1.JBO.21.6.061004
Published in: Journal of Biomedical Optics Volume 21, Issue 6
Show Author Affiliations
Jaime J. Bravo, Thayer School of Engineering at Dartmouth (United States)
Scott C. Davis, Thayer School of Engineering at Dartmouth (United States)
Dartmouth-Hitchcock Medical Ctr. (United States)
David W. Roberts, Dartmouth Hitchcock Medical Ctr. (United States)
Geisel School of Medicine at Dartmouth (United States)
Keith D. Paulsen, Thayer School of Engineering at Dartmouth (United States)
Dartmouth-Hitchcock Medical Ctr. (United States)
Geisel School of Medicine at Dartmouth (United States)
Stephen C. Kanick, Thayer School of Engineering at Dartmouth (United States)
Dartmouth-Hitchcock Medical Ctr. (United States)


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