The innovative optical filters achieve higher overall transmittance by connecting the peaks of the hemoglobin absorption spectrum (415 nm, 540 nm and 570 nm) creating a continuous wavelength spectrum. There are two modes with different OE filters (Mode 1 and Mode 2).
The optical filter used in this mode has a feature that enhances the contrast of blood vessels. There are two large absorption bands around 415 nm and around 540 nm in the absorption wavelength of hemoglobin. The surface of the mucous membrane and internal blood vessel can be easily identified by constructing an image with light that has a wavelength of around 415nm suitable for emphasizing blood vessels on the surface of the mucous membrane and light with a wavelength of around 540 nm suitable for emphasizing blood vessels inside the mucous membrane.
The filter used in this mode transmits long-wavelength light (red) as well as light that has the characteristics suitable for high-lighting blood vessels as mentioned in the section about Mode 1 (lights with wavelengths around 415 nm and around 540nm). A combination of these 3 lights allows a highlighting effect, which can be obtained in Mode 1 and the creation of images close to natural, white-light images.
Mode 1 is designed mainly to improve visualization of microvessels with a sufficient amount of light, and Mode 2 is designed to improve contrast of white-light observation by bringing the color tone of the overall image closer to that of natural color (white color tone) with much more light than that of the Mode 1 filter. By using the optical filter (Mode 1 or Mode 2), the microvascular patterns in addition to microsurface patterns on the mucosal surface are clearly observed, which means that the knowledge obtained by optical chromoendoscopy could potentially be brought into the i-scan technology. According to recent publications by using OE Mode 2 and Mode 1, it was found that these methods may be useful for detection and characterization of gastrointestinal neoplasms, respectively.1
1Neumann et al. Present and future perspectives of virtual chromoendoscopy with i-scan and optical enhancement technology. Digestive Endoscopy 2013; 26 doi: 10.1111/den.12190