Abstract
Delta-aminolevulinic acid/protoporphyrin IX is applied for fluorescent tumor detection in the upper part of gastrointestinal tract. The 5-ALA is administered per os six hours before measurements at dose 20 mg/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. Through endoscopic instrumental channel a fiber is applied to return information about fluorescence to microspectrometer. In such way, 1D detection and 2D visualization of the lesions' fluorescence are received, and both advantages and limitations of these methodologies are discussed in relation to their clinical applicability. Comparison of the spectra received from normal mucosa, inflammatory, and tumor areas is applied to evaluate the feasibility for development of simple but effective algorithm based on dimensionless ratio of the fluorescence signals at 560 and 635 nm, for differentiation of normal/abnormal gastrointestinal tissues.
Highlights
The limitations of standard endoscopy for detection and evaluation of cancerous changes in gastrointestinal tract are significant challenge and initiative development of new diagnostic modalities, including optical detection of tissues alterations
Variation of Xillix fluorescent endoscopic system is Xillix-LIFE-GI which is applied for autofluorescence detection of stomach neoplasia and has approval for Japan and European countries
The fiber bundle is specially developed for endoscopic applications in gastrointestinal tract (Polironik Ltd., Moscow, Russia), as the bundle used in this case consists of 8 quartz fibers, central one with diameter 200 μm, and surrounding 7 fibers with diameter 100 μm, all of them with numerical aperture 0.22
Summary
The limitations of standard endoscopy for detection and evaluation of cancerous changes in gastrointestinal tract are significant challenge and initiative development of new diagnostic modalities, including optical detection of tissues alterations. Fluorescent diagnosis of tumor tissues becomes a valuable tool in the clinical practice This technique could be applied for detection and evaluation of tumors in different localizations using endoscopic equipment. Fluorescent gastroscopes are still on its research and development phases and from the best we know that the few existing systems, such as Olympus Evis Lucera, have not received yet approvals from FDA for access to the broad clinical market [5]. This system is a digestive tract videoscope used for observing blood vessels in mucous membranes under infrared light in the regions 790–820 nm and 905– 970 nm. Variation of Xillix fluorescent endoscopic system is Xillix-LIFE-GI which is applied for autofluorescence detection of stomach neoplasia and has approval for Japan and European countries
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