Introduction: What Are New Roles of Current Colonoscopy?

The recent advances in endoscopic imaging technologies make great changes in the management of colorectal polyps. These changes include optical histologic diagnosis with high definition colonscopy, new management strategies such as resect and discard or do not resect, and differentiation of depth of submucosal invasion. In this focused review series, these new paradigms in management of colorectal polyps are discussed by three, world famous authors. First, Amit Rastogi explained optical diagnosis of small colorectal polyp with high definition colonoscopy using narrow band imaging. Second, Cesare Hassan explained new paradigms for colonoscopic management of diminutive colorectal polyps: resect and discard or do not resect. In the last, Shinji Tanaka described, in detail, endoscopic assessment of invasive colorectal cancer: slight vs. deep submucosal invasion. These focused review series introduce the new roles of current colonoscopy to readers and will help the readers to know how to use the new imaging technologies and paradigms in clinical practices.

Optical Diagnosis of Small Colorectal Polyp Histology with High-Definition Colonoscopy Using Narrow Band Imaging

Optical diagnosis of polyp histology can potentially result in enormous cost savings by way of the "resect and discard" strategy for diminutive polyps and the "do not resect" strategy for diminutive hyperplastic polyps in the distal colon. Narrow Band Imaging (NBI) highlights the surface mucosal and vascular pattern on polyps and has been shown to accurately characterize adenomatous and hyperplastic polyps by experts. However, the results have been a little discouraging amongst lesser experienced endoscopists. Studies have also shown that using the NBI diagnosis of diminutive polyp histology, experts can accurately define the future surveillance colonoscopy intervals. However nonexperts in academic or community setting have as yet failed to achieve the recommended thresholds. The subjectivity in assessment by endoscopists leads to the variable accuracy rates and can be circumvented by computer based automated tools. Although initial experience with a few computer based algorithms have shown accuracies comparable to experts, further refinement and validation will be required before these can be implemented in clinical practice. Incorporation of optical diagnosis of diminutive polyps into clinical practice is bound to face several hurdles. But the potential for enormous cost saving makes it an attractive strategy that can make colonoscopy more cost effective.