Early Detection of Bladder Cancer Using Autofluorescence, ALA-Induced PpIX Fluorescence and Diffuse Reflectance (original) (raw)

1997, Lund Reports in Atomic Physics

In this study three optical methods, autofluorescence, ALA-induced PpiX fluorescence and diffuse reflectance have been evaluated regarding their ability to detect malignant and dysplastic changes of human bladder tissue, in vivo. For the autofluorescence method, a single-fiber system based on a N2-laser was used. The 337 nm laser light excited the bladder tissue and the fluorescence was detected with an optical multichannel analyzer (OMA). The differences in the spectra from normal and malignant sites were investigated and the results showed a good demarcation between these tissue types. The sensitivity, specificity and positive and negative predictive values (non-malignant versus malignant) were found to be 73, 90, 73 and 90%, respectively. The second method utilized 5-aminolevulinic acid (ALA), which has a tendency to predominantly accumulate in malignant tissue. Through the heme cycle the ALA is converted to protoporphyrin IX (PpiX) which fluoresces red when excited with blue light. A filtered xenon-lamp was used to excite the PpiX and the red fluorescence was detected with a CCD camera mounted on a cystoscope. The images were stored on S-VHS tapes and the results were compared with the visual diagnosis made by the surgeon during the procedure as well as with the pathology report, if a biopsy of the site was taken. The easiness with which the PpiX is excited and the fluorescence detected, and the high tumor selectivity of ALA, make ALA-induced PpiX fluorescence a very helpful tool in finding tumors. The diffuse reflectance method utilized a white light source (xenon-lamp) and an OMA system to record the diffuse reflectance. By comparing the spectral differences between the malignant and non-malignant sites, a quantitative measure of the concentration of hemoglobin was obtained. In practice, this method showed only what was visible to the eye, that the tumor sites appeared red. Though, it provides a quantitative measure and avoids a subjective bias from the surgeon.