Fluorescence imaging of early lung cancer

Using a ratio fluorometer probe, tissue autofluorescence induced by a krypton ion laser in normal bronchial tissues and early lung cancer was found to be different. In vivo spectroscopic measurements using an optical multichannel analyzer also showed an overall decrease in autofluorescence in the tumor tissues. Because tissue autofluorescence is not uniform, the technique of ratioing may not be reliably applied to bronchoscopic imaging of early lung cancer to cancel the dependence of fluorescence intensity on the distance, angle, and irradiance of the excitation light. This can, however, be overcome by other mathematical transformations of the autofluorescence images of the two spectral regions.