| [ Summary ] |
Despite expanding knowledge concerning endoscopic features, the detection of early gastric cancer (EGC) during routine EGC remains difficult, because there are few morphologic changes. Dye-based image enhancement methods have been developed and widely used in Japan. 0.04-0.2% indigocarmine creates contrast images of the mucosal topography, 0.05-0.1% methylene blue stains intestinal metaplasia. In addition EGC are observed as nonstained areas. The endoscopic Congo red methylene blue method can make it possibleto visualize EGC as a nondiscolored area within the discolored area, methylene blue unstained areas in discolored areas, and areas where both dye bleached. An advantage of choromoendoscopy over conventional endoscopy, is that it is especially useful, for flat and early stage neoplasias. It is apparent, however, that one of the limitations of this method is that it is a somewhat complicated and time-consuming procedure. Narrow Band Imaging (NBI) produces contrast surface images of structures and vessel patterns in the superficial mucosa through illumination of two specific narrow band short wavelength illumination. Moreover, the combination of NBI with magnifying endoscopy enables us to evaluate the detailed morphological features of the epithelia in relation to histology. Autofluorescence imaging videoendoscopy systems (AFI) produce real-time color images of natural tissue fluorescence from endogenous fluorophores through light excitation. This technology helps to depict differences in autofluorescence features as color variations in endoscopic images. EGC in the fundic mucosa appears as green areas on a purple background, whereas tumors in the pyloric or atrophic mucosa appear purple on a green background. Equipment-based image enhanced endoscopy, such as NBI or AFI, does not eliminate the need for other types of diagnostic endoscopy, especially for pretreatment evaluation. These methologies provide an alternative for most cases which require routine examinations because they are easier to use and produce no adverse reactions. |