Abstract
Background: White light endoscopy suffers from differentiation between Barrett's mucosa with and without dysplasias. Time gated detection of protoporphyrin IX (PpIX) fluorescence allows the simultaneous performance of endoscopy and fluorescence imaging. In a previous study (Ortner et al., GUT 2003;52:28-33) we were able to demonstrate, that with time gated fluorescence spectroscopy the detection of dysplasias can be improved significantly. The aim of this study was to improve the diagnostic capability of fluorescence guided endoscopy by presenting the information of fluorescence intensity as an overlay on the endoscopic image and to shorten the time for endoscopic investigation. Methods: In 16 patients (70% male,age 64 [48-77 y]) with known or suspected Barrett's esophagus fluorescence endoscopy was performed about 2 hours after topical application of 500 mg 5-aminolaevulinic acid. Biopsies were taken at positions with high fluorescence intensity by using the novel overlay technique and for control at locations with no intensity from areas with columnar lined epithelium. Subsequently the biopsy samples were analyzed by fluorescence spectroscopy immediately after the examination. Moreover, all samples were sent to pathology for routine histologic examination. Results: A total of 84 biopsies were investigated. Samples from Barrett's mucosa showed significantly higher fluorescence intensity of (PpIX) as compared to regular columnar lined epithelium (median 0.23 for columnar lined mucosa vs. 0.99 for Barrett's mucosa, p < 0.0009 (two sample t test). Moreover, samples with low grade dysplasia (LGD) showed a higher fluorescence intensity than Barrett's biopsies without dysplasias. However, this trend was not statistically significant, most probably due to the small number of biopsies with LGD. Conclusion: Fluorescence spectroscopy seems to be more specific than wide field illumination most likely due to focal inspection and less bleaching of fluorescence. In patients with known or suspected Barrett's esophagus time gated fluorescence overlay imaging can improve the detection of Barrett's esophagus or dysplastic epithelium by identifying the regions with high fluorescence intensity. The detection rate for dysplastic lesions may therefore be increased and time for endoscopic investigation could be shortened compared to other enhanced techniques.
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