Cystoscopic photodetection of human bladder carcinoma without sensitizing agents

We demonstrate that bladder tissue autofluorescence provides more adequate information for tumor demarcation, thus eliminating the need for sensitizing agents. During initial experiments, autofluorescence spectra were recorded with an optical multichannel analyzer for both normal and tumor bladder tissue upon excitation with the third harmonic of a pulsed Nd:YAG laser (355 nm). In both cases, the spectra show a relatively broad peak centered at 470 nm accompanied by a long tail extending into the red. However, malignant tumors show a decrease of the 470 nm peak by approximately a factor of 2.5 with respect to normal tissue, while the red tail (λ>600 nm) of the spectrum remains unaffected. As a result, the ratio F of the autofluorescence signals at 470 nm and 630 nm can be used as a demarcation function, independent of both the excitation energy and the collection efficiency of the optical system. From the insights gained in these experiments, we have developed and extensively tested in vivo a cystoscopic fiber optic diagnostic system