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Proceedings Paper

Fluorescence spectroscopy of gastrointestinal tumors using δ-ALA
Author(s): E. G. Borisova; B. G. Vladimirov; I. G. Angelov; L. A. Avramov
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Paper Abstract

In the recent study delta-aminolevulinic acid/Protoporphyrin IX (&dgr;-ALA/PpIX) is used as fluorescent marker for dysplasia and tumor detection in esophagus and stomach. The &dgr;-ALA is administered per os six hours before measurements at dose 20mg/kg weight. High-power light-emitting diode at 405 nm is used as an excitation source. Special opto-mechanical device is built to use the light guide of standard video-endoscopic system (Olimpus Corp.). Through endoscopic instrumental channel a fiber is applied to return information about fluorescence to microspectrometer (USB4000, OceanOptics Inc.). The fluorescence detected from tumor sites has very complex spectral origins. It consists of autofluorescence, fluorescence from exogenous fluorophores and re-absorption from the chromophores accumulated in the tissue investigated. Mucosa autofluorescence lies at 450-600 nm region. The fluorescence of PpIX is clearly pronounced at the 630-710 nm region. Deep minima in the tumor fluorescence signals are observed in the region 540-575 nm, related to hemoglobin re-absorption. Such high hemoglobin content is an indication of the tumors neovascularisation and it is clearly pronounced in all dysplastic and tumor sites investigated. The lack of fluorescence peaks in the red spectral area for normal mucosa is an indication for selective accumulation of &dgr;-ALA/PpIX only in abnormal sites and gives high contrast when lesion borders are determined from clinicians during video observation in the process of diagnostic procedure. Very good correlation between fluorescence signals and histology examination results of the lesions investigated is achieved.

Paper Details

Date Published: 5 March 2007
PDF: 5 pages
Proc. SPIE 6604, 14th International School on Quantum Electronics: Laser Physics and Applications, 66042H (5 March 2007); doi: 10.1117/12.727716
Show Author Affiliations
E. G. Borisova, Institute of Electronics (Bulgaria)
B. G. Vladimirov, Univ. Hospital Queen Jovanna (Bulgaria)
I. G. Angelov, Institute of Organic Chemistry (Bulgaria)
L. A. Avramov, OPTELLA Ltd. (Bulgaria)

Published in SPIE Proceedings Vol. 6604:
14th International School on Quantum Electronics: Laser Physics and Applications

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