Laser-induced autofluorescence of human colonic tissues

ABSTRACTThe purpose of this study is to perform a preliminary evaluation of the diagnostic potential of laser-induced autofluorescence (LIAF) spectroscopy for colonic tumours using fluorescence intensity ratios at specific wavelengths.Measurements were made on normal mucosa and adenocarcinoma of human colon tissues. Each tissue section wasexamined using an optical probe consisting of a central fiber for delivering the excitation laser and a fiber bundle fordetection of the fluorescence. Using different wavelengths of a CW mixed-gas (Ar/Kr) laser, we measured and analyzedthe LIAF spectra of tissues through a polychromator coupled with a CCD detector. It can be found that in the range of520-620nm, the spectral shapes of tumour tissues are very similar to the normal tissue spectra, and the autofluorescenceintensities of normal tissues are about threefold higher than those of tumour tissues. However, in the range of 625- 720nm, the autofluorescence intensities of tumour tissues are higher than those of normal tissues. The spectral