Current clinical techniques

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.

Confocal endomicroscopy

the most abundant optical sectioning imaging technique.