Spectral study of metabolism-based autofluorescence and white-light reflectance for endoscopic tumor imaging.

Metabolism-based autofluorescence redox imaging is one of the promising options for non-invasive screening of digestive tumors. In this paper, autofluorescence from fluorescent coenzymes such as NADH and FAD related to cellular metabolism as well as total hemoglobin and oxygen saturation are analyzed based on a point spectrum. As a redox index based on the metabolism, the ratio of the 450nm-490nm fluorescence intensities for 365nm and 405nm excitation wavelengths (F365/F405) is used. Although F365/F405 is a good index in many samples, inversion and weakened contrast are observed. A Simplified models with and without collagen based on Lambert-Beer law are built to explain how F365/F405 depicts the tumor region.

Dual-band multi-aperture enhanced redox imaging of colonic adenomas for endoscopes with a high-performance CMOS imager.

Dual-band multi-aperture imaging of colonic adenomas based on the redox condition of mucosal cells for next-generation endoscopes is proposed. A low-noise and high-dynamic-range CMOS imager with the folding integration and the cyclic ADC is utilized in the single-imager multi-aperture camera system with 475-nm and 530-nm band-pass filters. A redox image is calculated from four kinds of images, 475-nm and 530-nm fluorescence images for 365-nm and 405-nm excitation lights. Dark current and random noise are reduced with a selective averaging method. The contrast of the redox image has been successfully enhanced.