Macroscopic and microscopic fluorescence spectroscopy of colorectal benign and malignant lesions - diagnostically important features.

E Borisova,O Semyachkina-Glushkovskaya,I Terziev,M Lomova,L Avramov,B Vladimirov,T Genova,D Bratashov

doi:10.1364/boe.10.003009

Abstract

Fluorescence spectroscopy is a sensitive, fast and non-invasive tool for a diagnostics of cancerous gastrointestinal lesions. It could be applied for in situ detection of tumours during primary endoscopic observations or as add-on measurement modality during microscopic observations of tissue histology slides for their initial or retrospective diagnosis. Therefore, we are looking for diagnostically important features of normal and cancerous tissue areas in a broad spectral range for gastrointestinal tissues ex vivo using two steady-state macroscopic fluorescent spectroscopic modalities and by confocal fluorescent microscopic detection. Results obtained from autofluorescence spectroscopy of benign and malignant lower part gastrointestinal tract (GIT) lesions from freshly excised tissues during surgical removal of the lesions in 18 patients (22 lesions), were compared with the spectral measurements obtained during confocal fluorescent microscopy observations of unstained tissue slides using 405 nm excitation. Excitation-emission matrices (EEMs) were used for ex vivo measurements with applied excitation in 280-440 nm spectral region and emission observed between 300 and 700 nm. Synchronous fluorescence spectroscopy (SFS) approach was also applied to improve the spectral resolution of the observed complex emission spectra. Specific fluorescent features observed, related to presence of structural proteins, co-enzymes and endogenous porphyrins in the tissues investigated, allow discriminating normal mucosa from benign polyps and malignant carcinoma lesions with diagnostic accuracy up to 94.4%.

Highlights

Fluorescent analysis of gastrointestinal tissues recently became attractive mode for detection and differentiation of neoplasia in colon and rectum
In our previous studies we demonstrated Excitation–emission matrices (EEMs) and Synchronous fluorescence spectroscopy (SFS) maps of colon and rectum neoplasia, compared with the normal mucosa data to present the endogenous fluorophores appearance in the specific tissue areas [12]
Weak signal observed from NADH is due to the work with ex vivo tissue samples, where the emission of this metabolic indicator rapidly decreased after surgical excision procedure and could not be used in the current study as diagnostically significant indicator for the tissue alterations, which could be done correctly only during in vivo tissue investigations, or if time between the excision and spectral measurement could be taken into account [22,23,24,25]

Summary

Introduction

Fluorescent analysis of gastrointestinal tissues recently became attractive mode for detection and differentiation of neoplasia in colon and rectum. Auto uorescence spectroscopy is one of the most intensively investigated add-on techniques for endoscopic gastrointestinal diagnostics It is a powerful technique for noninvasive analysis of malignant tissues [3]. No requirements for application of exogenous contrast agents for visualization of neoplastic alterations make this technique a desired tool for endoscopic observations in situ during standard colonoscopy procedures. This technique could be highly beneficial for initial diagnosis of suspicious tissue presence, for guided biopsy sampling, providing spectral data and images in vivo, in real time, characterized with different spectral peculiarities depending of benign or malignant lesions examined [4,5,6,7,8]

Methods

Results

Conclusion