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 obta ined and analyzed fluorescence spectra from 75 patients in whom bladde r cancer was suspected. Tissue fluorescence was excited by a nitrogen laser using a quartz optical fiber placed in gentle contact with the a rea of interest. The laser-induced autofluorescence spectrum was recor ded using an intensified optical multichannel analyzer system. Spectra were corrected for the spectral response of the optical system, and t he 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 blad der lesions (erythematous, edematous, raised and so forth) that were d ifficult to diagnose by cystoscopy as well as areas from which random biopsies were obtained. The fluorescence ratio algorithm was applied t o 130 bladder areas. Results: Of the 130 biopsies obtained during rout ine cystoscopy 107 (82%) were nonmalignant by histological classificat ion. In contrast, because laser-induced autofluorescence effectively g uides 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. Co nclusions: By guiding the surgeon to suspicious lesions that are most likely to be malignant, laser-induced autofluorescence substantially d ecreases the number of biopsies obtained from nonmalignant tissue duri ng cystoscopy to diagnose bladder carcinoma.