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27 December 1995 Fluorescence imaging and spectroscopy of ALA-induced protoporphyrin IX preferentially accumulated in tumor tissue
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In a clinical pilot study performed on 104 patients suffering from bladder cancer it could be shown that intravesical instillation of a solution of 5-aminolevulinic acid (5-ALA) induces a tumorselective accumulation of Protoporphyrin IX (PPIX). Malignant lesions could be detected with a sensitivity of 97% and a specificity of 67%. The Kr+-laser as excitation light source could successfully be replaced by a filtered short arc Xe-lamp. Its emission wavelength band (375 nm - 440 nm) leads to an efficiency of 58% for PPIX- excitation compared to the laser. Two-hundred-sixty mW of output power at the distal end of a slightly modified cystoscope could be obtained. This is sufficient for recording fluorescence images with a target integrating color CCD-camera. Red fluorescence and blue remitted light are displayed simultaneously. Standard white light observation is possible with the same instrumentation. Pharmacokinetic measurements were performed on 18 patients after different routes of 5-ALA application (oral, inhalation and intravesical instillation). PPIX-fluorescence measurements were made on the skin and on the blood plasma. Pharmacokinetic of 5-ALA could be performed on blood plasma. Endoscopical florescence spectroscopy showed the high fluorescence contrast between tumor and normal tissue with a mean value of 10.7. Forthcoming clinical multicenter studies require an objective measure of the fluorescence intensity. Monte Carlo computer simulations showed that artifacts due to observation geometry and varying absorption can largely be reduced by ratioing fluorescence (red channel of camera) to remission (blue channel). Real time image ratioing provides false color images with a reliable fluorescence information.
© (1995) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Herbert G. Stepp, Reinhold Baumgartner, Wolfgang Beyer, Ruth Knuechel, T. O. Koerner, M. Kriegmair, Kai Rick, Pia Steinbach, and Alfons G. Hofstetter "Fluorescence imaging and spectroscopy of ALA-induced protoporphyrin IX preferentially accumulated in tumor tissue", Proc. SPIE 2627, Optical Biopsies, (27 December 1995);

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