Autofluorescence guided biopsy for the early diagnosis of bladder carcinoma

Purpose: We validate the usefulness of laser-induced autofluorescence for the detection of bladder carcinoma. Materials and Methods: We obtained and analyzed fluorescence spectra from 75 patients in whom bladder cancer was suspected. Tissue fluorescence was excited by a nitrogen laser using a quartz optical fiber placed in gentle contact with the area of interest. The laser-induced autofluorescence spectrum was recorded using an intensified optical multichannel analyzer system. Spectra were corrected for the spectral response of the optical system, and the ratios of laser-induced autofluorescence intensities (I) at 385 and 455 nm. (I-385/I-455) were determined. We had previously established this ratio as a diagnostic algorithm. We included only suspicious bladder lesions (erythematous, edematous, raised and so forth) that were difficult to diagnose by cystoscopy as well as areas from which random biopsies were obtained. The fluorescence ratio algorithm was applied to 130 bladder areas. Results: Of the 130 biopsies obtained during routine cystoscopy 107 (82%) were nonmalignant by histological classification. In contrast, because laser-induced autofluorescence effectively guides biopsies towards malignant lesions, only 30 biopsies (72% fewer) would have been obtained from nonmalignant tissue if the fluorescence ratio that identifies 95% of malignant lesions (95th percentile) had been selected as the decision criterion during standard cystoscopy. Conclusions: By guiding the surgeon to suspicious lesions that are most likely to be malignant, laser-induced autofluorescence substantially decreases the number of biopsies obtained from nonmalignant tissue during cystoscopy to diagnose bladder carcinoma.