Time gated fluorescence spectroscopy in Barrett's oesophagus

Abstract

Background and aims: Specialised intestinal metaplasia and its dysplastic transformation, which precedes cancer in Barrett's oesophagus cannot be differentiated in standard gastroscopy. The aim of this study was to investigate whether laser induced protoporphyrin IX fluorescence permits the detection of specialised intestinal metaplasia and dysplasia during endoscopy and to take biopsy specimens in a guided rather than random manner. Methods: In 53 patients with Barrett's oesophagus 5-aminolaevulinic acid was sprayed on the mucosa. Approximately 60 to 120 minutes later, biopsy specimens were taken based on point-like measurements of delayed fluorescence intensity ratios of protoporphyrin IX in vivo. Two independent pathologists examined the 596 biopsy specimens taken, 168 of which were selected to be investigated by a third pathologist. Among these specimens only those (n=141) with a consensus diagnosis by at least two pathologists and p53 expression as additional marker were included in the analysis. Results: The median of normalised fluorescence intensity (ratio of delayed PpIX fluorescence intensity to immediate autofluorescence intensity) in non-dysplastic specialised intestinal metaplasia (0.51, 68% CI 0.09 to 1.92) and low grade dysplasia (1.89, 68% CI 0.55 to 3.92) differed significantly (p<0.005). Dysplasia was detected at a rate 2.8-fold higher compared with screening endoscopy despite taking fewer specimens. In addition, three early cancers were detected for the first time. Moreover, this method permitted differentiation of specialised intestinal metaplasia from junctional or gastric-fundic type epithelium (p<0.013). Conclusions: For the first time it was possible to differentiate low grade dysplasia from non-dysplastic Barrett's mucosa during endoscopy based on delayed laser induced fluorescence endoscopy of PpIX. Furthermore, the method helps to detect specialised intestinal metaplasia in short Barrett's oesophagus.

How to Improve Quality Assurance in Fluorometry: Fluorescence-Inherent Sources of Error and Suited Fluorescence Standards

“…This assumption is generally justified for the detection of early stages of cancerous tissue. On the basis of this normalization procedure, a significant discrimination between diseased and non-diseased tissue is possible as has been shown for example by Ortner et al for dysplasias in Barrett's oesophagus [157].…”

“…For excitation and observation of laser-induced fluorescence an optical fiber is inserted into the working channel of an endoscope. This technique enables the measurement of spectrally resolved fluorescence data at a single point [157,158] and can be applied for fluorescence-guided biopsy. The fluorescence spectra from the blue spot in Fig. 14 taken at two different delay times relative to the exciting laser pulse are illustrated in Fig.…”

Light-Induced Fluorescence Techniques for Gastrointestinal Tumour Detection

“…Indeed, when video-observation is applied, it is not easy to differentiate the red signal coming from inflammatory area and from neoplastic lesion, but when point spectroscopy is applied, one could observe significant differences in the intensity levels of 5-ALA/PpIX fluorescence at 635 nm. Therefore, point spectroscopy allows to reach higher specificity of the diagnosis (Georgakoudi, 2001, Ortner, 2003, than video-endoscopic observation (Endlicher, 2001;. If compare relative intensities of normal and abnormal tissues sites for esophagus and stomach (see fig.…”

Detection and staging of esophageal cancers

“…This agent is fluorescent and was reported to enhance the detection of high-grade dysplasia in 20 patients with 77% sensitivity and 71% specificity using porphyrin fluorescence alone [12]. A larger study using amino levulinic acid and time-fated fluorescence in 53 patients found that there was significantly more normalized fluorescence in dysplastic tissue compared with nondysplastic [13]. However, the confidence intervals for these normalized values overlap to a large extent.…”