Elsevier

Gastrointestinal Endoscopy

Volume 91, Issue 1, January 2020, Pages 104-112.e5
Gastrointestinal Endoscopy

Original article
Clinical endoscopy
Linked color imaging versus narrow-band imaging for colorectal polyp detection: a prospective randomized tandem colonoscopy study

https://doi.org/10.1016/j.gie.2019.06.031Get rights and content

Background and Aims

Linked color imaging (LCI) is a newly available image-enhanced endoscopy (IEE) system that emphasizes the red mucosal color. No study has yet compared LCI with other available IEE systems. Our aim was to investigate polyp detection rates using LCI compared with narrow-band imaging (NBI).

Methods

This is a prospective randomized tandem colonoscopy study. Eligible patients who underwent colonoscopy for symptoms or screening/surveillance were randomized in a 1:1 ratio to receive tandem colonoscopy with both colonoscope withdrawals using LCI or NBI. The primary outcome was the polyp detection rate.

Results

Two hundred seventy-two patients were randomized (mean age, 62 years; 48.2% male; colonoscopy for symptoms, 72.8%) with 136 in each arm. During the first colonoscopy, the polyp detection rate (71.3% vs 55.9%; P = .008), serrated lesion detection rate (34.6% vs 22.1%; P = .02), and mean number of polyps detected (2.04 vs 1.35; P = .02) were significantly higher in the NBI group than in the LCI group. There was also a trend of higher adenoma detection rate in the NBI group compared with the LCI group (51.5% vs 39.7%, respectively; P = .05). Multivariable analysis confirmed that use of NBI (adjusted odds ratio, 1.99; 95% confidence interval, 1.09-3.68) and withdrawal time >8 minutes (adjusted odds ratio, 5.11; 95% confidence interval, 2.79-9.67) were associated with polyp detection. Overall, 20.5% of polyps and 18.1% of adenomas were missed by the first colonoscopy, but there was no significant difference in the miss rates between the 2 groups.

Conclusion

NBI was significantly better than LCI for colorectal polyp detection. However, both LCI and NBI missed 20.5% of polyps. (Clinical trial registration number: NCT03336359.)

Introduction

Early detection of colorectal polyps and their subsequent removal by polypectomy are the cornerstone of colorectal cancer prevention.1 Colonoscopy is therefore generally considered as the criterion standard for the detection and treatment of colorectal polyps. However, several studies have found that up to 32% of adenomas can be missed during colonoscopy.2, 3, 4 Missed adenomas are of great concern and are believed to be an important cause of the development of interval colorectal cancer, that is, cancer detected before the expected surveillance interval.

Image-enhanced endoscopy (IEE) has been used frequently in clinical practice for polyp detection and characterization. Among the various IEE modalities, narrow-band imaging (NBI) is one of the most widely used. However, there are conflicting data on whether NBI can actually increase the adenoma detection rate based on the results of the 3 previous meta-analyses published in 2015.5, 6, 7 With improvements in the light source and image resolution, the new generation of NBI can achieve brighter and sharper endoscopic images. We have previously shown that the use of the new generation of NBI had a significantly higher adenoma detection rate than conventional white-light colonoscopy.8

Linked color imaging (LCI) is a new mode of IEE, produced by Fujifilm (Tokyo, Japan), with a different mode of wavelength optimization using all 3 primary colors (red, blue, and green). It is designed to detect subtle color differences in the red GI mucosa, enhancing the contrast of hemoglobin for detection of the mucosal vascular pattern. Further signal processing enhances the red color and makes the white color whiter (Fig. 1). In a recent study,9 the adenoma miss rate of LCI was 8%, which was significantly lower than that of white-light endoscopy. Other studies have also suggested that LCI increases the detection rate of sessile serrated polyps10 and proximal colonic polyps11 compared with white-light colonoscopy. However, there is as yet no direct head-to-head comparison of LCI and other imaging modalities for colorectal polyp detection. In this prospective randomized tandem colonoscopy study, we aimed to compare the polyp detection rates of the newly available LCI with the NBI, a commonly used IEE system.

Section snippets

Study design

This was a prospective randomized tandem colonoscopy study conducted in the Integrated Endoscopy Centre of the Queen Mary Hospital in Hong Kong, which is a major regional hospital as well as a university teaching hospital. This study was initiated by the investigators and was registered in ClinicalTrials.gov (NCT03336359).

Study participants

Consecutive adult patients, aged between 40 and 80 years, undergoing colonoscopy in the Queen Mary Hospital were invited to participate in this study. The indications for

Patients

Between October 2017 and June 2018, 547 patients were screened for eligibility. After excluding illegible patients, 272 patients were enrolled with 136 patients in each arm (Fig. 2). The baseline characteristics of the enrolled patients are shown in Table 1. The indications for colonoscopy were for work-up of bowel symptoms in 72.8%, whereas screening and surveillance colonoscopy accounted for 11.4% and 15.8%, respectively. There were more symptomatic patients in the LCI group than in the NBI

Discussion

This is the first prospective randomized tandem colonoscopy study that directly compares the newly available LCI with NBI for detection of colorectal polyps. Although LCI aims to enhance the red color of the mucosa and facilitate polyp detection, we found that the polyp detection rate, serrated lesion detection rate, and the median number of polyps detected on the first colonoscopy were all significantly lower in the LCI group than in the NBI group. There was also a borderline trend of a higher

Acknowledgments

We are grateful to all patients and endoscopy nurses at the Queen Mary Hospital for their contribution to this study.

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    DISCLOSURE: All authors disclosed no financial relationships relevant to this publication.

    See CME section; p. 162.

    If you would like to chat with an author of this article, you may contact Dr Leung at [email protected].

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