Autofluorescence spectroscopy of normal and malignant tissues: Both in vivo and ex vivo measurements in the upper aero-digestive tract and lung tissues

A spectroscopic system with flexible three optical fiber sensor had been developed to study tissue fluorescence for a clinical use. Autofluorescence spectra at 413nm and 10mW excitation light power from different tissues in oral cavity had been measured in vivo in 25 subjects. The correlation coefficient in spectral shape between individual spectra and the mean emission spectrum of each site was about 0.9 and fluorescence intensity variation ranged between 20% and 45% according to the examined site. The variation in fluorescence intensity of the main emission wavelength at about 520nm between spectra of the lower part of tongue, gingiva, lips, floor of cavity, cheek and palate was not statistically significant. But the spectrum of the upper part of tongue had been characterized by an additional peak around 635nm. Otherwise, autofluorescence spectra at 410nm and 0.5mW excitation light power of 8 carcinoma of buccal and lung tissues were measured. The fluorescence ratio at 520nm emission peak between normal tissue and carcinoma was evaluated at a maximum value of 13 for a lung cancer (ex vivo measurement) and a minimum of 3.3 for a cancer of the oro-pharynx (in vivo measurement). On the other hand, a fluorescence peak at 635nm had characterized the carcinoma of the floor of cavity and the upper part of tongue.