A Prospective Randomized Study of Colonoscopy Using Blue Laser Imaging and White Light Imaging in the Detection and Differentiation of Colonic Polyps

Detailed Summary

The adenoma detection rate by colonoscopy for asymptomatic individuals aged 50 years and older is estimated to be at least 25%. It is known that during colonoscopy, lesions may be missed. Image enhanced endoscopy techniques have been evaluated for the detection and differentiation of colonic polyps. Narrow band imaging (NBI), is one such technique. The common classification systems used predict histology is the NICE and the Sano and JNET classification. The NICE classification can be used without optical magnification; it evaluates the color of the lesion, regularity of the overlying vessels and regularity of the surface pattern. The Sano and JNET classification requires optical magnification in order to assess the capillary patterns such as whether there is dilation, irregularity or loss of irregular capillaries over the lesion. In the context of adenoma detection, the results are more contentious. A meta-analysis of randomized studies examining the utility of the first generation NBI system when compared to high definition WLI showed no difference in detection rates. A criticism of the NBI system had been the dark endoscopic view; this is a result of the optical filter, and can limit the far view. A second generation NBI system has since been developed. It is characterized by much brighter illumination despite the optical filter, and thus the far view is improved. A recent randomized controlled study compared the second-generation NBI system with high definition WLI. NBI was shown to improve polyp and adenoma detection rates compared to WLI. Blue laser imaging (BLI) is another form of narrow bandwidth imaging developed by Fujifilm Corporation (Tokyo, Japan). Instead of using an optical filter for white light to produce narrow bandwidths, the BLI system has a unique feature of illumination using two lasers and a white light phosphor to accomplish the visual enhancement of surface vessels and structures. This study aims to determine whether BLI can increase the detection rate of colonic polyps and adenomas when compared to white light endoscopy, with the null hypothesis being no difference in detection rates. This study will also examine the use of NICE and Sano/ JNET classification systems to predict histology with the BLI system.

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