Linked-color imaging (LCI) significantly increases the detection of adenomas in screening colonoscopies compared to white-light imaging (WLI) and blue-laser imaging (BLI)–bright, according to data from 205 adults who underwent screening colonoscopies.
LCI is a relatively new image-enhancement method designed to better identify adenomatous lesions by increasing the contrast of the mucosal surface, wrote Carlos E.O. dos Santos, MD, of Pontifícia Universidade Católica do Rio Grande do Sul in Porto Alegre, Brazil, and colleagues. Their report is in the Journal of Clinical Gastroenterology. With LCI, the lesions are more vascularized, and thus become reddish due to color contrast of hemoglobin present in capillary vessels, whereas the surrounding mucosa becomes whitish. Until this new study, the potential of LCI to detect adenomas compared with other imaging had not been evaluated.
The researchers randomized 205 patients with a total of 296 colorectal lesions to WLI, BLI-bright, or LCI; 70 patients were examined by WLI, 66 by BLI-bright, and 69 by LCI. The average age of the patients was 59 years, and 52% were women. The primary outcome measures were adenoma detection rate (ADR), mean number of adenomas per patient, and withdrawal time.
A total of 251 adenomas were detected, with an overall ADR of 62%. The total number of adenomas detected by each method were 112 by LCI, 71 by WLI, and 68 by BLI-bright.
The ADR was significantly higher for patients in the LCI group compared with those in the WLI group (71% vs. 52.9%, P = .04). ADR for LCI was greater than the ADR for BLI-bright, but the difference was not significant (71% vs. 62.1%, P = .28). No significant differences in ADR were noted between the WLI and BLI-bright groups.
The mean number of adenomas identified per patient was 1.17 overall, but significantly higher in the LCI group compared to the WLI and BLI-bright groups (1.62, 1.01, and 1.03, respectively, P = .02). Mean withdrawal times were not significantly different among the three groups and ranged from approximately 10 to 11 minutes. An analysis of secondary outcomes showed no differences among the groups in terms of size and morphology of the adenomas, or in the detection of sessile serrated adenomas or polyps.
The researchers noted that the study findings were limited by several factors including the use of data from a single center with a high level of experience in image-enhanced endoscopy and by the relatively small sample size.
Nevertheless, concluded the researchers, “It is evident that better visibility of the mucosa is a key factor for the detection of neoplastic lesions,” and the results support the potential of LCI given the demonstrated superiority of LCI over WLI for colorectal adenoma detection and the mean number of adenomas detected per patient.
The researchers said that further single and multicenter randomized studies are needed to validate the results and to confirm whether one image-enhancement system is superior to the other for increasing the ADR.
Door is open for better detection tools
In an interview, Atsushi Sakuraba, MD, of the University of Chicago, who was not involved with the study, said that colonoscopy is considered the best method for colorectal cancer screening and prevention, but is associated with a certain risk of missing adenomas, so new methods and technologies to improve detection rate are needed. “Linked-color imaging provides an increased contrast of the mucosal surface and enhances the findings of adenomatous lesions in comparison to white-light endoscopy and has been shown to be effective in detecting adenomas, so the findings of the present study are not surprising,” said Dr. Sakuraba.
LCI provides clearer and brighter images by enhancing the differences in color contrast, and therefore does not cause the impaired visibility that can occur with narrow band imaging or BLI images, Dr. Sakuraba said. However, he noted, not all endoscopy centers carry the scopes equipped with LCI, which is a barrier to widespread use.
Dr. Sakuraba said that multicenter studies need to be undertaken to confirm the generalizability of the results of the present study.
“There is now convincing evidence that increasing adenoma detection rate is associated with fewer missed cancers and lower mortality from colorectal cancer,” said Ziad F. Gellad, MD, of Duke University, Durham, N.C., who was also not involved with the study. “As such, utilizing tools that enhance ADR may improve our ability to prevent colorectal cancer. ... Understanding the relative benefits and drawbacks of available tools and technologies in the market can help practicing gastroenterologists decide where to invest their time and resources to improve care.”
Dr. Ziad F. Gellad
Dr. Gellad said he was not surprised by the enhanced detection using LCI, as the study is not the first to evaluate this technology. “However, I was surprised by how high the ADR was in the screening population (62%),” said Dr. Gellad, observing that this exceeds benchmarks set by the society. “We don’t have a full understanding of the demographic characteristics of this screening population. ... Nonetheless, I think this paper adds to accumulating data that current benchmarks may be too low.”
Dr. Gellad said he didn’t think the findings of the study are strong enough to change practice, but the results are a “valuable contribution to the literature and will empower future larger studies as well as meta-analyses.” He called for larger studies in nonspecialized centers to relate the findings from this small study to general practice.
The study received no outside funding. The researchers had no financial conflicts to disclose. Dr. Sakuraba disclosed collaborative research relationships with Fuji, the manufacturer of the imaging equipment used in the study. Dr. Gellad had no financial conflicts to disclose but serves on the editorial board of GI & Hepatology News.