The impact of narrow band imaging in screening colonoscopy: a randomized controlled trial

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.

Narrow-band imaging as an alternative to chromoendoscopy for the detection of dysplasia in long-standing inflammatory bowel disease: a prospective, randomized, crossover study

BACKGROUND

Narrow-band imaging (NBI) is a novel technique that may represent an alternative method to chromoendoscopy (CE) for the detection of colitis-associated intraepithelial neoplasia (IN) in patients with long-standing inflammatory bowel disease (IBD).

OBJECTIVE

To compare NBI with CE for the detection of IN.

DESIGN

Prospective, randomized, crossover study.

SETTING

Academic hospital.

PATIENTS

Patients with clinically inactive colonic IBD (≥8 years).

INTERVENTION

Patients underwent both CE and NBI in randomized order. Targeted biopsy specimens from abnormal areas were obtained. Pathological examination was regarded as the reference standard.

MAIN OUTCOME MEASUREMENTS

Number of false-positive and true-positive lesions in patients undergoing CE and NBI were compared as well as the proportion of patients with missed IN lesions.

RESULTS

Eighty patients were screened, of whom 20 were excluded. Mean ± standard deviation withdrawal time for CE was significantly longer than that for NBI (26.87 ± 9.89 minutes vs 15.74 ± 5.62 minutes, P < .01). Thirteen patients had at least 1 IN lesion on 1 of the examinations. In the per-lesion analysis, NBI resulted in a significantly inferior false-positive biopsy rate (P = .001) and a similar true-positive rate. The percentage of missed IN lesions and patients was superior with NBI, albeit without reaching statistical significance.

LIMITATIONS

Lesions were sampled immediately after detection, which precluded the possibility of paired analysis.

CONCLUSIONS

NBI appears to be a less time-consuming and equally effective alternative to CE for the detection of IN. However, given the NBI lesion and patient miss rates, it cannot be recommended as the standard technique.

Narrow-band imaging does not improve detection of colorectal polyps when compared to conventional colonoscopy: a randomized controlled trial and meta-analysis of published studies

BACKGROUND

A colonoscopy may frequently miss polyps and cancers. A number of techniques have emerged to improve visualization and to reduce the rate of adenoma miss.

METHODS

We conducted a randomized controlled trial (RCT) in two clinics of the Gastrointestinal Department of the Sanitas University Foundation in Bogota, Colombia. Eligible adult patients presenting for screening or diagnostic elective colonoscopy were randomly allocated to undergo conventional colonoscopy or narrow-band imaging (NBI) during instrument withdrawal by three experienced endoscopists. For the systematic review, studies were identified from the Cochrane Library, PUBMED and LILACS and assessed using the Cochrane risk of bias tool.

RESULTS

We enrolled a total of 482 patients (62.5% female), with a mean age of 58.33 years (SD 12.91); 241 into the intervention (NBI) colonoscopy and 241 into the conventional colonoscopy group. Most patients presented for diagnostic colonoscopy (75.3%). The overall rate of polyp detection was significantly higher in the conventional group compared to the NBI group (RR 0.75, 95%CI 0.60 to 0.96). However, no significant differences were found in the mean number of polyps (MD -0.1; 95%CI -0.25 to 0.05), and the mean number of adenomas (MD 0.04 95%CI -0.09 to 0.17). Meta-analysis of studies (regardless of indication) did not find any significant differences in the mean number of polyps (5 RCT, 2479 participants; WMD -0.07 95% CI -0.21 to 0.07; I2 68%), the mean number of adenomas (8 RCT, 3517 participants; WMD -0.08 95% CI -0.17; 0.01 to I2 62%) and the rate of patients with at least one adenoma (8 RCT, 3512 participants, RR 0.96 95% CI 0.88 to 1,04;I2 0%).

CONCLUSION

NBI does not improve detection of colorectal polyps when compared to conventional colonoscopy (Australian New Zealand Clinical Trials Registry ACTRN12610000456055).

Evolving techniques in colonoscopy

PURPOSE OF REVIEW

This review summarizes recent clinical studies of colonoscopy technique and new technologies.

RECENT FINDINGS

Water immersion reduces pain and sedation doses in unsedated and lightly sedated colonoscopy. Cap-fitted colonoscopy makes insertion faster and improves detection of lesions behind folds, but the latter effect is operator-dependent. A single controlled trial showed improved detection with the Third Eye Retroscope, but the two arms of the study were not controlled for withdrawal time. Chromoendoscopy increases detection of diminutive adenomas, but adds time to the colonoscopy procedure. Electronic chromoendoscopy methods (narrow band imaging, Fujinon Intelligent ChromoEndoscopy, i-scan, and autofluorescence) have been either unsuccessful in improving detection or require more study. However, these methods and several other methods (chromoendoscopy with magnification, confocal laser microscopy, and endocytoscopy) allow accurate real time determination of polyp histology.

SUMMARY

Water immersion is a clear advance in unsedated colonoscopy. Cap-fitted colonoscopy is a promising method for both practical and effective visualization of the proximal sides of haustral folds. Electronic chromoendoscopy has been largely ineffective at improving polyp detection, but is effective (as are confocal laser microscopy and endocytoscopy) for diagnosis of polyp histology.

Endoscopic trimodal imaging detects colonic neoplasia as well as standard video endoscopy

BACKGROUND & AIMS

Endoscopic trimodal imaging (ETMI) is a novel endoscopic technique that combines high-resolution endoscopy (HRE), autofluorescence imaging (AFI), and narrow-band imaging (NBI) that has only been studied in academic settings. We performed a randomized, controlled trial in a nonacademic setting to compare ETMI with standard video endoscopy (SVE) in the detection and differentiation of colorectal lesions.

METHODS

The study included 234 patients scheduled to receive colonoscopy who were randomly assigned to undergo a colonoscopy in tandem with either ETMI or SVE. In the ETMI group (n=118), first examination was performed using HRE, followed by AFI. In the other group, both examinations were performed using SVE (n=116). In the ETMI group, detected lesions were differentiated using AFI and NBI.

RESULTS

In the ETMI group, 87 adenomas were detected in the first examination (with HRE), and then 34 adenomas were detected during second inspection (with AFI). In the SVE group, 79 adenomas were detected during the first inspection, and then 33 adenomas were detected during the second inspection. Adenoma detection rates did not differ significantly between the 2 groups (ETMI: 1.03 vs SVE: 0.97, P=.360). The adenoma miss-rate was 29% for HRE and 28% for SVE. The sensitivity, specificity, and accuracy of NBI in differentiating adenomas from nonadenomatous lesions were 87%, 63%, and 75%, respectively; corresponding values for AFI were 90%, 37%, and 62%, respectively.

CONCLUSIONS

In a nonacademic setting, ETMI did not improve the detection rate for adenomas compared with SVE. NBI and AFI each differentiated colonic lesions with high levels of sensitivity but low levels of specificity.

The clinical efficacy and future perspective of narrow band imaging for the diagnosis of colorectal neoplasm

Growing body of evidences have shown that narrow band imaging (NBI) can be the adjunct tool of colonoscopy for real time or optical histological assessment with high accuracy and largely replaces the role of chromoendoscopy. In spite of the advantages, there are still several issues that remain to be elucidated: detectability of neoplastic lesions, diagnosis of malignant transformation, evaluation of invasion depth for cancerous lesion, morphological diagnosis and interobserver agreement. Endoscopists should be aware of the advantage, current evidence and the limitation of narrow band imaging and apply it appropriately for their clinical practice.

The water method combined with chromoendoscopy enhances adenoma detection

BACKGROUND: The water method is easy-to-learn and improves colonoscopy outcomes. Dye-spray chromoendoscopy enhances ADR but has not been widely accepted for routine application in screening or surveillance colonoscopy. HYPOTHESIS: With dye added to the water used in the water method, ADR can be enhanced compared with the water or air method alone. OBJECTIVE: To compare ADR determined by the air method, water method alone, and water method with indigo carmine (0.008%) added. DESIGN: Review of prospectively collected data in a performance improvement program. SETTING: VA endoscopy unit. PATIENT: Screening or surveillance colonoscopy. METHODS: Patients (n=50/group) underwent colonoscopy with each of the three methods. Water method involved warm water infusion in lieu of air insufflation coupled with removal of residual air by suction and residual feces by water exchange. ADR and procedural data were collected prospectively to monitor performance. MAIN OUTCOME MEASUREMENTS: ADR. RESULTS: ADR in the air method, water method alone and water method with indigo carmine were 36%, 40% and 62%, respectively. Water method with indigo carmine produced significantly higher ADR than the air or water method alone (p<0.05). LIMITATIONS: Non-randomized data, single VA site, retrospective comparison. Absence of significant difference between air and water methods could be a type II error due to small number of patients CONCLUSIONS: The approach with indigo carmine added to the water used in the water method yielded significantly higher ADR than the water or the air method alone. The data suggest that a prospective RCT to compare the different methods is warranted.

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.

Chromoscopy versus conventional endoscopy for the detection of polyps in the colon and rectum

BACKGROUND

Although conventional colonoscopy is the most sensitive test available for the investigation of the colorectum for polyps, there are data that raise concerns about its sensitivity. Chromoscopy may be one way of enhancing the ability for colonoscopy to detect polyps particularly diminutive flat lesions that may be otherwise difficult to detect.

OBJECTIVES

To determine whether the use of chromoscopy enhances detection of polyps and neoplasia during endoscopic examination of the colon and rectum.

SEARCH STRATEGY

MEDLINE, EMBASE and the Cochrane Library databases were searched (April 2010) along with a hand search of abstracts from relevant meetings. Search terms included randomised trials containing combinations of the following: 'chromoscopy' 'colonoscopy' 'dye-spray' 'chromo-endoscopy' 'indigo-carmine' 'magnifying endoscopy'.

SELECTION CRITERIA

All prospective randomised trials comparing chromoscopic with conventional endoscopic examination of the lower gastrointestinal tract were included. Patients with inflammatory bowel disease or polyposis syndromes were excluded.

DATA COLLECTION AND ANALYSIS

Two reviewers assessed the methodological quality of potentially eligible trials and independently extracted data from the included trials. Outcome measures included the detection of polyps (neoplastic and non-neoplastic), the detection of diminutive lesions, the number of patients with multiple neoplastic lesions and the extubation time.

MAIN RESULTS

Five trials were included in this update, and although there were some methodological drawbacks and differences in study design, combining the results showed a significant difference in favour of chromoscopy for all detection outcomes. In particular, chromoscopy is likely to yield significantly more patients with at least one neoplastic lesion (OR 1.67 (CI 1.29-2.15)) and significantly more patients with three or more neoplastic lesions (OR 2.55 (CI 1.49-4.36)). Not surprisingly the withdrawal times were significantly slower for the chromoscopy group.

AUTHORS' CONCLUSIONS

There appears to be strong evidence that chromoscopy enhances the detection of neoplasia in the colon and rectum. Patients with neoplastic polyps, particularly those with multiple polyps, are at increased risk of developing colorectal cancer. Such lesions, which presumably would be missed with conventional colonoscopy, could contribute to the interval cancer numbers on any surveillance programme.

Efficacy and effectiveness of colonoscopy: how do we bridge the gap?

Colonoscopy is sometimes considered the preferred colorectal cancer screening modality, yet this modality may be subject to variation in operator performance more than any other screening test. Failures of colonoscopy to consistently detect precancerous lesions threaten the effectiveness of this technique for the prevention of colorectal cancer. Studies on high-level adenoma detectors under optimal conditions have begun to establish the true efficacy of colonoscopy and further widen the gap between efficacy and effectiveness. Research is required to establish the component skills, attitudes, and behaviors for high-level mucosal inspection competence necessary for training and assessment. Interventions to bridge the gap between efficacy and effectiveness are lacking, yet they should emphasize quality measurement and operate at various levels within the health system to motivate change in endoscopist behavior.

Performance improvements of imaging-based screening tests

Endoscopic and radiologic tests appear to be more accurate than stool-tests in detecting advanced neoplasia because of direct visualisation of colorectal mucosa. Further technological advances are expected to improve the performance and acceptability of these tests. Several attempts at increasing the adenoma detection rate of colonoscopy have been tested, and in vivo histologic differentiation between neoplastic and hyperplastic polyps may lead to substantial saving in economic and medical resources. Low-volume and non-cathartic bowel preparations may improve CT colonography acceptability, whilst computer-aided detection and low-dose protocols may result in a higher accuracy and safety of this procedure. Despite the lack of ionising radiation, significant drawbacks will likely to limit the role of MR colonography in screening programs. Colon capsule endoscopy appears to be a safe and technically feasible procedure. The suboptimal accuracy of the first generation seems to be substantially improved by the second generation of this device.

Impact of narrow-band imaging in screening colonoscopy

Narrow band-imaging (NBI) enhances mucosal visualization of the vascular network and surface structure and helps to increase the visibility of neoplasia by improving contrast. Studies on the detectability of colorectal neoplastic lesions using NBI have primarily been reported in Western countries, but the published opinions and conclusions remain controversial at the present time. Our earlier prospective pilot study demonstrated that NBI colonoscopy significantly improved detection of flat lesions, which are more likely to be missed, particularly on the right side of the colon. It is especially important that even examiners performing routine screening colonoscopies become sufficiently familiar with flat and depressed lesions and then take full advantage of the endoscopic systems and specific image enhancement functions currently available for improved detection of flat and diminutive lesions. Adequate bowel preparation is another important consideration.

Efficacy of computed virtual chromoendoscopy on colorectal cancer screening: a prospective, randomized, back-to-back trial of Fuji Intelligent Color Enhancement versus conventional colonoscopy to compare adenoma miss rates

BACKGROUND

Colonoscopy is the criterion standard for screening of colorectal neoplasms. Nonetheless, a substantial miss rate with conventional, white-light colonoscopy (WL) remains a challenge.

OBJECTIVE

To assess whether Fuji Intelligent Color Enhancement (FICE) can detect more adenomas than WL in screening colonoscopy.

DESIGN

Prospective, randomized trial of tandem colonoscopy adjusted for withdrawal time and lavage effect.

SETTING

Seoul National University Hospital Healthcare System Gangnam Center, Korea.

PATIENTS

This study involved 359 average-risk adults undergoing screening colonoscopy.

INTERVENTION

Patients were randomized to the first withdrawal with either FICE (FICE-WL group) or WL (WL-FICE group).

MAIN OUTCOME MEASUREMENTS

The primary end point measure was the difference in adenoma miss rates, and the secondary outcome measure was the adenoma detection rate.

RESULTS

We enrolled 359 patients (mean age 50.6 years, male 66.9%) and randomly assigned 181 to the WL-FICE group and 178 to the FICE-WL group. The number of adenomas detected by FICE and WL was 123 and 107, respectively. The adenoma miss rate with FICE showed no significant difference compared with that of WL (6.6% vs 8.3%, P = .59). Characteristics of lesions missed by use of FICE were similar to those missed by use of WL; 93% of overall missed polyps were < or =5 mm, and none were > or =1 cm. All missed adenomas were low grade and nonpedunculated. There was no significant difference between FICE and WL in adenoma detection rate (mean 0.64 vs 0.55 per patient, P = .65) nor percentage of patients with > or =1 adenoma (33.7% vs 30.4%, P = .74).

LIMITATIONS

Single-center study.

CONCLUSION

FICE at screening colonoscopy did not improve the adenoma miss rate or detection rate compared with WL.

Image-enhanced endoscopy is critical in the detection, diagnosis, and treatment of non-polypoid colorectal neoplasms

Colonoscopy, the most sensitive test used to detect advanced adenoma and cancer, has been shown to prevent colorectal cancer (CRC) when combined with polypectomy. CRC remains the third most commonly diagnosed cancer and the second leading cause of cancer death in men and women in the United States. Image-enhanced endoscopy (IEE) is an integral part in the detection, diagnosis, and treatment of non-polypoid colorectal neoplasms. Both the dye-based and equipment-based varieties of IEE are readily available for application in today's practice of colonoscopy. Data are available to support its use, although further studies are needed to simplify the classification of colorectal lesions by the different techniques of equipment-based IEE.

An advanced chromocolonoscopic picture is worth a thousand words, but is it worth the effort?

Chromocolonoscopy is a commonly used advanced or multimodal colon imaging method to interrogate the colon mucosa and colon polyps. The two main objectives of chromocolonosopy are to (a) detect a colon polyp and (b) define (differentiate) the lesion. Although data supporting the use of chromocolonoscopy for colon polyp detection are not strongly founded, this technique may be helpful in differentiating colon polyps and may aid in their endoscopic resection.

High-definition colonoscopy detects colorectal polyps at a higher rate than standard white-light colonoscopy

BACKGROUND & AIMS

Adenoma detection rates might be improved through use of high-definition colonoscopy, which can detect subtle mucosal changes. We investigated whether the use of high-definition white-light (HDWL) colonoscopy resulted in a higher rate of adenoma detection than standard-definition white-light (SDWL) colonoscopy in a clinical practice setting.

METHODS

This retrospective study included 2430 patients who underwent colonoscopies from September 2006 to December 2007; 1226 received SDWL colonoscopy and 1204 received HDWL colonoscopy. We analyzed data from consecutive screening, surveillance, and diagnostic colonoscopies, comparing adenoma and overall polyp detection between procedures. Potentially confounding variables were controlled using multivariable logistic regression analysis.

RESULTS

The adenoma detection rate was higher among patients who underwent HDWL compared with SDWL colonoscopies (28.8% vs 24.3%; P = .012), as was the polyp detection rate (42.2% vs 37.8%; P = .026). These findings remained after adjustments for potentially confounding variables (P = .018 and .022, respectively).

CONCLUSIONS

In a general clinical practice setting, HDWL colonoscopy resulted in a higher adenoma detection rate compared with SDWL colonoscopy. The use of SDWL colonoscopy could reduce the number of missed adenomas and the subsequent risk for colorectal cancer.

Half doses of PEG-ES and senna vs. high-dose senna for bowel cleansing before colonoscopy: a randomized, investigator-blinded trial

OBJECTIVES

Patients' compliance with and tolerance of large-volume polyethylene glycol electrolyte solution (PEG-ES) have prompted continuous investigation with alternative forms of cleansing. High-dose senna is superior to PEG-ES for the quality of bowel cleansing, patient compliance, and tolerance, but its acceptance may be influenced by the incidence of abdominal pain. We hypothesized that a combination of half doses of PEG-ES and senna could minimize the incidence of abdominal pain without affecting the quality of bowel preparation.

METHODS

This randomized, investigator-blinded trial has been conducted on consecutive outpatients scheduled for elective colonoscopy at a single community-based hospital. Patients were randomly assigned to receive either 12 tablets of 12 mg senna and 2 l of PEG-ES (half-dose group, HDG) or 24 tablets of senna divided in two doses (senna group, SG) the day before colonoscopy. The main outcome measures were the quality of colon cleansing (Aronchick scoring scale) and the incidence of preparation-related abdominal pain. Secondary outcome measures were patients' compliance with the cleansing regimen, overall tolerability, prevalence of predefined side effects, and quality of right colon cleansing.

RESULTS

A total of 296 patients were enrolled (HDG=151 and SG=145). Overall cleansing was excellent to good in 90.1 and 88.3% patients in HDG and SG, respectively (P=0.62). Preparation-related moderate-to-severe abdominal pain was reported by 6% patients in HDG and 15.2% in SG (P=0.009). No significant differences were observed for secondary outcomes.

CONCLUSIONS

The regimen combining half doses of PEG-ES and senna provides high-quality bowel preparation and acceptable patient tolerance, with less abdominal pain compared with high-dose senna.