Narrow band imaging at colonoscopy: seeing through a glass darkly or the light of a new dawn?

The impact of EndoCuff-assisted colonoscopy on the polyp detection rate: A cross-over randomized back-to-back study

BACKGROUND AND STUDY AIMS

Colorectal cancer (CRC) is one of the most common cancers worldwide, and most CRCs develop from polyps with malignant potential. We aimed to study the difference in polyp detection rate between EndoCuff-assisted colonoscopies (EAC) and standard colonoscopy (SC).

PATIENTS AND METHODS

This study was conducted at Cairo University Hospitals on patients referred for screening or diagnostic colonoscopy from July 2018 to August 2020. All included patients underwent back-to-back standard colonoscopy (SC) and ENDOCUFF VISION-assisted colonoscopies (EAC).

RESULTS

214 patients were included in this study. In comparison between EAC and SC, EAC increased the polyp detection rate (69 (32.24 %) vs. 57(26.64 %) (p < 0.05), EAC increased the detection of diminutive polyps ≤ 5 mm (104 vs. 81) (p < 0.05), and small polyps 6-9 mm (12 vs. 10) while there was no difference in large polyps ≥ 10 mm. EAC increased the adenoma detection rate (ADR) (37 (17.2 %) vs. 32(14.9 %) (p < 0.05). The findings detected by EAC shortened the interval of surveillance determined by SC findings. EndoCuff caused six mucosal erosions (2.8 %) in patients.

CONCLUSION

EAC increases the number of detected colonic polyps, primarily small polyps on the left and right sides of the colon.

The use of optical imaging techniques in the gastrointestinal tract

With significant advances in the management of gastrointestinal disease there has been a move from diagnosing advanced pathology, to detecting early lesions that are potentially amenable to curative endoscopic treatment. This has required an improvement in diagnostics, with a focus on identifying and characterising subtle mucosal changes. There is great interest in the use of optical technologies to predict histology and enable the formulation of a real-time in vivo diagnosis, a so-called 'optical biopsy'. The aim of this review is to explore the evidence for the use of the current commercially available imaging techniques in the gastrointestinal tract.

Image-enhanced endoscopy technology in the gastrointestinal tract: what is available?

Gastrointestinal malignancy accounts for approximately a fifth of all cancer deaths in the United Kingdom. By the time patients are symptomatic, lesions are often advanced, with limited treatment options available. The development of effective endoscopic therapies means that neoplastic lesions can now be treated with improved patient outcomes. This has led to a paradigm shift, whereby the aim of digestive endoscopy is to identify premalignant conditions or early neoplastic change, in order to make an impact on their natural history. This has necessitated an improvement in imaging techniques in order to identify subtle mucosal changes that may harbour precancerous cells. At present there is an array of available imaging modalities, each with implications on cost, training and lesion detection. Here we describe the scientific rationale behind the major commercially available techniques as well as offering a glimpse at possible future directions.

Narrow-band imaging in the colon: limitations and potentials

Narrow-band imaging (NBI) is a new endoscopic technology that highlights surface structures and superficial mucosal capillaries during colonoscopy at a single push of a button. NBI has a high sensitivity and specificity for differentiating neoplastic and non-neoplastic polyps by means of mucosal and capillary patterns. It is also useful in determining the invasion depth of early colorectal cancers and evaluating free margins after endoscopic resection. However, it has not been shown to improve the adenoma detection rate compared with white-light endoscopy. Although narrow-band imaging is now available commercially, its role in routine clinical practice during colonoscopy is not well defined. The difficulties in interpreting results partly relate to different NBI nomenclatures used in classifying colonic adenomas and their lack of standardization. Future research should focus on establishing a reliable NBI nomenclature for capillary patterns, defining the learning curve and interobserver variation, and validating the effectiveness of NBI in routine colonoscopy.

High-definition and filter-aided colonoscopy

New high-resolution colonoscopes and filter technologies are allowing us to visualize more lesions and better characterize lesions within the gastrointestinal tract. In light of recent findings that flat and serrated lesions are more likely to contain invasive cancer and that even small lesions (5-10 mm) may contain advanced histology, detecting these lesions earlier with improved optical technologies may help decrease the rate of interval cancers after colonoscopy. With the limited accuracy of white-light colonoscopy (59%-84%) in distinguishing non-neoplastic lesions from neoplastic lesions, these new technologies can help us improve our abilities to risk stratify patients and determine more precise surveillance intervals.