Use of fibre optic probes for detection of Barrett's epithelium in the rat oesophagus by Raman spectroscopy

In the last decades, there has been a dramatic increase in the incidence of Barrett's oesophagus and the associated oesophageal adenocarcinoma. Therefore, patients with a Barrett's oesophagus undergo regular endoscopic surveillance with randomly taken biopsies to detect the presence of high-grade dysplasia or carcinoma. Sampling errors and observer variation, inherent to such a surveillance protocol warrant other detection methods. Raman spectroscopy is a non-invasive optical spectroscopic technique that provides detailed information about the molecular composition and structure of tissues. Changes in molecular composition in tissues as a consequence of pathologic processes, can thus be recognised. For clinical application of Raman spectroscopy, thin and flexible fibre optic probes can be used that fit in the auxiliary channel of an endoscope. In this study, a multivariate classification model was developed for detection of Barrett's epithelium, based on ex vivo Raman spectra of the rat oesophagus. The spectra were collected with three different fibre optic probes and on 11 different days. This mimics the way a database is collected in a clinical situation, including all instrument calibration, probe-to-probe and day-to-day variation. After elimination of interfering background signal contributions from the different probes using a vector-correction procedure, we could discriminate between Barrett's and normal epithelium with accuracy higher than 93%. The model yields a spectral discriminant that best separates the two groups. To facilitate interpretation of this discriminant, we obtained Raman spectra from tissue sections of normal oesophageal epithelium, keratin and muscle layer using a confocal Raman microscope.

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