Chromocolonoscopy

Cap-Assisted Chromo-Colonoscopy: Are 2 Techniques Better Than None?

Cap-assisted and chromo-colonoscopy are 2 techniques which may increase adenoma detection; however, chromo-colonoscopy is limited by increased time requirement. In this edition of The American Journal of Gastroenterology, Kim et al. present data from a randomized controlled trial comparing standard colonoscopy with an arm using both techniques (CAP/CHROMO). The indigo carmine was applied using a simpler method than previous studies, resulting in shorter times. The CAP/CHROMO adenoma detection was higher than the controls (54.4% vs 44.9%; P < 0.001), but there was no difference for advanced neoplasia. If endoscopists find these data convincing, they should trial these techniques separately because each technique may have a different impact.

[Submucosal chromoendoscopy. A technique that highlights epithelia and differentiates histological components, and renders colon polypectomy easier and safer]

Submucosal chromoendoscopy involves the injection of a solution containing a vital stain, usually indigo carmine, into the intestinal wall submucosal layer. This allows to: Better delimit and characterize the various epithelia present (colonic mucosa, adenoma, hyperplastic polyp, serrated polyp, small bowel mucosa); expose and delimit lesion implantation areas; cooperate in the lifting of resectable lesions; ensure section across the submucosal plane; identify intestinal wall structures; render complex polypectomy feasible; and facilitate the identification of perforations.The present paper offers information on the endoscopic technique for submucosal injection, solution preparation and concentration, and on the potential benefits it may provide for polypectomy or endocopic mucosal resection whether en block or piecemeal. This endoscopic technique simultaneously combines a diagnostic and a therapeutic aspect, since lesion lifting in association with better delimited contours may improve not only accuracy but also endoscopic resection safety and feasibility.

Tools for polyp histology prediction

Although removal of adenomatous polyps has been shown to decrease the risk of colon cancer, distal hyperplastic polyps are thought to not have malignant potential. Most polyps detected during colonoscopy are diminutive (≤ 5 mm) and rarely harbor advanced histology, such as high-grade dysplasia or cancer. Therefore, predicting histology in real-time during colonoscopy can potentially decrease the enormous expenditure that ensues from universal histopathologic evaluation of polyps, and several novel imaging technologies have been developed and tested over the past decade for this purpose. Of these different technologies, electronic chromoendoscopy seems to strike a fair balance between accuracy, feasibility, and cost.

Dual optical modality endoscopic imaging of cancer development in the mouse colon

BACKGROUND AND OBJECTIVE

We utilize a miniature, dual-modality endoscope that combines fluorescence-based surface magnifying chromoendoscopy (SMC) and optical coherence tomography (OCT) to follow the anatomical changes that occur during adenoma development in the mouse colon.

MATERIALS AND METHODS

Twenty-five mice were treated with the carcinogen azoxymethane (AOM) to induce tumor development in the distal colon, or were treated with saline as control, and were imaged over six months. OCT detects adenoma number with high sensitivity and specificity and can measure lesion size. In methylene blue-lavaged colons, SMC detects changes in the colonic crypts. SMC images of control mouse colons exhibit reticulated patterns of crypts of equal size, forming either a dot or honeycomb pattern.

RESULTS

Images of AOM-treated colons show mild crypt irregularities even in grossly normal tissue. Images of small to medium adenoma exhibit larger crypts, more intense signal, and irregular spacing whereas those of large adenoma have heterogeneous, intense signal and loss of crypt structure.

CONCLUSIONS

The combination of OCT and SMC permits the detection of neoplastic events from the earliest stages of crypt irregularities before gross tissue changes are noted, through to measuring the growth of protruding adenoma.

Chromoendoscopy for colorectal cancer surveillance in patients with inflammatory bowel disease

Chromoendoscopy utilizes colorimetric techniques to increase detection of lesions that are difficult to see or cannot be seen with conventional white light endoscopy. Multiple studies have demonstrated that chromoendoscopy with dye spraying significantly increases the detection of dysplastic lesions in patients with chronic inflammatory bowel disease (IBD) of the colon undergoing colonoscopy. Furthermore, chromoendoscopy may obviate the need for random biopsies and pending additional studies and may allow increased intervals between surveillance exams, reducing costs while increasing the sensitivity for detection of dysplasia per exam. Despite convincing data supporting the use of chromoendoscopy for IBD colonic surveillance, it is seldom utilized outside of academic centers. Here, we review the current approach to colorectal cancer surveillance in IBD focusing on the data supporting the use of chromoendoscopy including its use in a community setting and offer practical recommendations for incorporating chromoendoscopy as a routine part of surveillance in IBD regardless of practice setting.