The Usefulness of I-scan in Screening Colonoscopy

Overview

Image-enhanced endoscopy in screening colonoscopy 1. useful tool for detecting subtle epithelial lesions 2. useful tool for predicting real-time histology of epithelial lesions. Among image-enhancing techniques, i-SCAN is new developed and the practical usefulness of i-scan for screening colonoscopy has not been investigated yet.

New technologies have been developed to enhance the visualization of colorectal mucosa to unmask even minute mucosal lesions and identify neoplastic lesion from non-neoplastic lesions. In particular, there appears to be strong evidence that pan-colonic chromoendoscopy enhances the detection of colorectal neoplasm in the colon and rectum. However, this technique is time-consuming because of both the dye spraying and suction of collected dye in the dependent portion, and therefore it is unsuitable for routine application. To overcome this inconvenience, optical-digital method involves conversion of the optical characteristics of the light used for illumination or imaging with a light source differing in optical characteristics from ordinary white light (WL), such as narrow band imaging (NBI), Fujinon imaging color enhancement (FICE), auto-fluorescence imaging (AFI) and infra-red imaging (IRI). I-scan technology is the newly developed image enhanced endoscopy technology, classified as a digital contrast method among endoscopic imaging techniques.19 I-scan has three modes of image enhancement, i.e. surface enhancement (SE); contrast enhancement (CE); and tone enhancement (TE). The three modes (SE, CE and TE) are arranged in series, therefore, it is possible to apply two or more of these three modes at one time. Switching the levels or modes of enhancements can be done on a real-time basis, without any time lag by pushing a relevant button, thus enabling efficient endoscopic observation. Furthermore, while NBI) images are much darker than conventional white light (WL) images, i-scan images are as bright as conventional WL images, therefore, i-scan is able to observe much larger areas in a distant view compared with NBI. Consequently, i-scan might be more useful for performing screening endoscopy). However, the actual usefulness of I-scan in enhancing the detection of colonic neoplastic lesions is not known yet in screening colonoscopy. Therefore, we tried to evaluate the hypothesis that, in subjects undergoing colonoscopy screening, the routine application of i-scan during withdrawal could improve adenoma detection as compared with standard WL examination.

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