Diagnosis of Colonic Adenomas by Bright Narrow Band Imaging (B-NBI)

Overview

Early detection of colo-rectal adenoma using colonoscopy can prevent occurrence of colon cancers. While colonoscopy is a standard technique, it can miss early cancers. To improve the detection rate, Narrow Band Imaging (NBI) was introduced in 2006. It has been shown to compare favorably with chromo-endoscopy in the sensitivity and specificity in the diagnosis of malignant colo-rectal neoplasms. The major drawback of NBI is that images become dark in the presence of blood and fecal matters. The bright-NBI is a prototype imaging technology that enables endoscopists to obtain better images in suboptimal conditions. The study proposes to compare the performance of colonoscopy using either white light or bright NBI in subjects undergoing screening colonoscopy in search for colon adenomas. Purpose To determine that bright -NBI is superior to WLE in detecting colorectal adenomas in average risk subjects undergoing screening colonoscopy.

Removal of colorectal adenomas prevents occurrence of cancers \[1\]. It is recognized that colonoscopy can miss colorectal adenomas and early cancers \[2\]. There is a need to further improve performance of colonoscopy. The use of chromo-endoscopy has been shown to improve detection of flat adenomas \[3\]. Narrow band imaging was introduced in year 2006. It is similar to chromo-endoscopy in that it provides more mucosal details. This enables endoscopists to accurately describe the pit pattern of adenomas. NBI has been used as a substitute to chromo-endoscopy. In pooled analysis, NBI is comparable to chromo-endoscopy in their sensitivity and specificity in the diagnosis of malignant colorectal adenomas \[4\]. Unfortunately, the use of NBI has not been shown to conclusively improve rate of colorectal adenoma detection. Two of 3 randomized trials that compared WLE to NBI showed a higher adenoma detection rate with the use of NBI \[5, 6\]. In a study by Rex et al., the rate was however similar with either modality. In a pooled analysis, NBI was only marginally better than WLE \[4\]. The effective use of NBI depends on the quality of bowel preparation and the experience of endoscopist. In the presence of fecal matters, NBI tends to be dark and detection of small adenomas becomes difficult. The prototype bright NBI coupled with high definition resolution is likely to overcome this drawback of original NBI.