Detection of adenocarcinoma in Barrett's oesophagus by means of laser induced fluorescence.

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Abstract
PATIENTS: Seven patients with Barrett's metaplastic epithelium and oesophageal adenocarcinoma were investigated by means of laser induced fluorescence after low dose intravenous injection (0.35 mg/kg bw) of Photofrin (QLT, Vancouver, Canada). Laser induced fluorescence measurements were performed immediately after resection of the oesophagus. METHODS: Laser induced fluorescence spectra were recorded from 15-30 locations in each surgical specimen from normal mucosa, Barrett's epithelium, and tumour tissue. Histological examination was performed on each location to correlate the fluorescence spectral characteristics with histological status of the epithelium (normal, metaplastic or malignant). Measurements were also performed during endoscopy in five patients to test the applicability of the method in a clinical setting. Fluorescence spectra were recorded and evaluated at characteristic wavelengths, and biopsy specimens were collected. Fluorescence ratios were calculated as the quotient of Photofrin fluorescence divided by autofluorescence. RESULTS: The mean (SD) fluorescence ratio values were 0.10 (0.058) for normal oesophageal mucosa, 0.16 (0.073) for normal gastric mucosa, 0.205 (0.17) for Barrett's epithelium with moderate dysplasia, 0.79 (0.54) for severe dysplasia, and 0.78 (0.56) for adenocarcinoma. The highest fluorescence ratios were obtained for adenocarcinoma tissue, which could generally be distinguished from all nonmalignant tissue. Metaplastic Barrett's epithelium also yielded higher fluorescence ratios than did normal mucosa. CONCLUSIONS: The results suggest that the technique can be used during endoscopy for real time tissue characterisation in the oesophagus, as an aid in detecting malignant transformation not macroscopically apparent at endoscopy.