Chromoendoscopy
1. stains or dyes may spray applied
*Absorptive stains:(e.g. Lugol's solution, methylene blue, crystal violet) identify specific epithelial cell types by preferential absorption or diffusion across cell membranes.
*Contrast stains:(e.g. indigo carmine) highlight surface topography by diffusing through mucosal crevices
*React stains: (e.g. congo red, phenol red) react with specific proteins causing a change in color.
Above stains are FDA-approved for the purpose of chromoendoscopy.
*Acetic acid: whitening dysplastic squamous lesions of the cervix and reddening Barrett's and gastric columnar epithelia in the esophagus.
2. white light
Commercial product：endocytoscopy (Olympus)
Digital chromoendoscopy
a stain-free method of enhencing the contrast of vascular network and surface texture of the mucosa.
#Narrow Band Imaging (NBI，Olympus)
illuminating the tissue with white light filtered by a bank of narrow color filter
#Vitrual Chromoendoscopy (Fujinon Intelligent Color Enhancement (PICE), Fujinon & I-Scan, Pentax,)
digital image processing of red-green-blue (RGB) color videos
Autofluorescence imaging
Autofluorescence imaging (AFI) is a stain-free technique which uses endogenous molecules such as collagen, flavins, and porphyrins as fluorescence contrast agents.
