Additional Techniques for Dysplasia Detection

Narrow band imaging (NBI) restricts light wavelengths to between 415 and 540 nm and provides improved visualization of mucosal and submucosal vasculature. Because of its success in identifying dysplasia in the esophagus, NBI has been studied as a method to improve detection of colonic dysplasia. Unfortunately, randomized trials have shown no benefit of NBI over high-definition colonoscopy for colitis-associated dysplasia. ^{57 58} Given the absence of any demonstrated benefit, NBI cannot be suggested in place of WLE alone. Confocal laser endomicroscopy (CLE), allowing real-time microscopic evaluation of the colonic mucosa, is an alternative approach for dysplasia detection. In small studies, CLE has been shown to have excellent accuracy compared with matched biopsies for the detection of dysplasia (accuracy: 97.8%); though not all studies have agreed on the performance of CLE. ^{58 59} CLE remains early in clinical development and current inconsistent reliability and high cost compared with traditional biopsy and histology still limit CLE technology to research use. The invasiveness and cost of colonoscopy combined with the remaining potential of missing dysplasia have raised interest in the use of DNA-based stool tests for CRC surveillance in IBD. A case–control study matching 19 patients with and 35 patients without colonic dysplasia or cancer found stool markers had sensitivities of 100% for carcinoma, 100% for HGD, and 67% for LGD, all with a specificity of 89%. ⁶⁰ While early in their evaluation, stool markers may serve as an important adjunct to CRC surveillance in IBD. Recent small pilot studies have demonstrated that methylated DNA targets associated with colonic neoplasia can be detected in the stool of IBD patients with adenomas. ⁸⁶ A key marker, methylated bone morphogenic protein 3 was present in to the stool of 63% of low-grade and 81% of high-grade dysplasia cases. While these results require replication and verification, stool-based DNA biomarkers for dysplasia may allow for targeted endoscopic surveillance and potentially reduce the frequency for colonoscopy.