LASER-INDUCED AUTOFLUORESCENCE DIAGNOSIS OF BLADDER-TUMORS - DEPENDENCE ON THE EXCITATION WAVELENGTH

Purpose: We assessed the ability of laser induced autofluorescence spe ctroscopy to distinguish neoplastic urothelial bladder lesions from no rmal or nonspecific inflammatory mucosa. Materials and Methods: Three different pulsed laser excitation wavelengths were used successively: 308 nm, (xenium chloride excimer laser), 337 nm. (nitrogen laser) and 480 nm. (coumarin dye laser). The excitation light was delivered by a specially devised multifiber catheter connected to a 1 mm, core diamet er silica monofiber introduced through the working channel of a standa rd cystoscope with saline irrigation. The captured fluorescence light was focused onto an optical multichannel analyzer detection system. De vice performance was evaluated in 25 patients after obtaining consent and immediately before transurethral resection of a bladder tumor. Spe ctroscopic results were compared with histological findings. Results: At 337 and 480 nm. excitation wavelengths the overall fluorescence int ensity of bladder tumors was clearly decreased compared to normal urot helial mucosa regardless of tumor stage and grade. At the 308 nm. exci tation wavelength the shape of the tumor spectra, including carcinoma in situ, was markedly different from that of normal or nonspecific inf lammatory mucosa. No absolute intensity determinations were required i n this situation, since a definite diagnosis could be established base d on the fluorescence intensity ratio at 360 and 440 nm. Conclusions: This spectroscopic study could be particularly useful design a simplif ied autofluorescence imaging device for detection of occult urothelial neoplasms.