Colorectal cancer (CRC) is the most devastating consequence of long-standing colitis in inflammatory bowel disease (IBD) patients. In a population-based study, the cumulative prevalence rates of CRC were 1%, 3%, and 7% after 10, 20, and 30 years of disease activity, respectively.1 The higher than expected rate of CRC underlies the importance of dysplasia surveillance programs in this population. However, one of the challenges faced by endoscopists is that the dysplasia seen in this cohort is mostly flat and subtle, which can be easily missed in the midst of mucosal inflammation and pseudopolyps. In addition, the use of low-definition, standard white-light colonoscopy and traditional practice of random quadrantic biopsy that only sample < 0.05% of the entire colonic mucosa lacks acceptable sensitivity and specificity in dysplasia identification and is associated with high rate of interval colitis-associated cancers.2 There is compelling evidence to support chromoendoscopy (CE) in dysplasia detection in long-standing IBD patients, and this technique has been endorsed for surveillance colonoscopy by all major guidelines including American Gastroenterological Association, American College of Gastroenterology, Crohn's and Colitis Foundation of America, European Crohn's and Colitis Organization, British Society of Gastroenterology, American Society for Gastrointestinal Endoscopy, the Australian National Health and Medical Research Council, and the Surveillance for Colorectal Endoscopic Neoplasia Detection and Management in Inflammatory Bowel Disease Patients: International Consensus Recommendations. However, despite guideline recommendations, CE has not been widely adopted into clinical practice, mainly related to the cumbersome and time-consuming technique.3 Many endoscopists prefer to use non-dye-based digital image enhancement, such as narrow band imaging, although there is currently a lack of evidence that narrow band imaging improves the detection of dysplasia over and above CE in IBD patients.4 Recent innovations, such as confocal laser endomicroscopy and autofluorescence imaging, have been evaluated in dysplasia surveillance in IBD and appear promising in improving neoplasia detection.5-7 However, studies performed to date are small, and larger studies are clearly needed to evaluate the accuracy of these new technologies to determine their role in dysplasia screening algorithm for IBD patients. Other new imaging modalities in development are Fuji Intelligent Chromoendoscopy and i-scan that utilize surface and tone enhancement via a digital image processing algorithm, which avoids the use of contrast to better define and outline mucosal structures in real time. However, there is no study to date on the use of such technology in dysplasia surveillance in IBD patients.8 Optical coherence tomography is another new innovative imaging modality that has mainly been evaluated in Barrett's surveillance and not yet in dysplasia detection in IBD. This technology utilizes an optical probe that is balloon-centered that can be placed endoscopically to provide radial imaging scan using infrared light, capturing 1200 images over 90 s. However, given the limited performance data currently available, this technology is mainly assessed in research setting.9 Recently, a new imaging modality became available in Australia known as full spectrum endoscopy (FUSE) that maintains the capability of an adult colonoscope but has additional camera lenses to the right and left sides of the tip of the scope providing a near-panoramic 330-degree endoscopic view of the mucosa as opposed to the restricted 170-degree endoscopic view from conventional forward viewing colonoscopes. Improved visualization of the side walls, blind spots, and behind mucosal folds allows more colonic lesions to be identified, hence reducing polyp miss rates. A recent tandem back-to-back screening colonoscopy study of a non-IBD population demonstrated a significant reduction in sporadic colonic adenoma miss rates from 41% to 7% using forward viewing colonoscopes versus FUSE, respectively.10 FUSE colonoscopy has yet to be evaluated for IBD dysplasia and the benefit of FUSE in comparison against the current gold standard technique of dye-spray CE also remains unknown. In summary, improvements in the optics of endoscopes and the use of CE have improved our ability to detect dysplasia. However, the current strategies used still remains inadequate, and the development of CRC continues to fuel ongoing research in advanced endoscopic imaging techniques to improve the efficacy of dysplasia surveillance. These emerging modalities appear promising and may change our traditional approach to dysplasia screening in IBD patients in the years ahead. A major hurdle continues to be the low uptake of CE in IBD surveillance.
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Jun 1, 2016
Michele Norgia + 2
Open Access
