A prospective randomised study on narrow-band imaging versus conventional colonoscopy for adenoma detection: does narrow-band imaging induce a learning effect?

The Miss Rate for Colorectal Adenoma Determined by Quality-Adjusted, Back-to-Back Colonoscopies

BACKGROUND/AIMS

Colonoscopy is considered to be the gold standard for detecting adenomatous polyps. Polyps are missed during colonoscopic examination at a rate that varies from 6% to 27%. The adenoma miss rate affects colonoscopic surveillance intervals and procedural quality. We aimed to assess the adenoma miss rate and the variables affecting the rate using same-day, quality-adjusted, back-to-back colonoscopies.

METHODS

This prospective study was performed at a single institution and included 149 patients. Two consecutive same-day colonoscopies were performed by two experienced endoscopists. The adenoma miss rates and variables affecting the missed adenomas, including polyp characteristics and procedure times, were evaluated.

RESULTS

The miss rates of polyps, adenomas, and advanced adenomas were 16.8%, 17%, and 5.4%, respectively. The smaller polyps and increased number of polyps detected during the first colonoscopy were more likely to be missed. A longer insertion time during the colonoscopy was correlated with an increased adenoma detection rate.

CONCLUSIONS

There was a significant miss rate in the detection of colonic adenomas even in quality-adjusted, back-to-back colonoscopies. The adenoma miss rate can be reduced with a sufficient observation time during colonoscopic insertion. The development of specific technological methods to reduce the adenoma miss rate is necessary.

Diagnostic performance of chromoendoscopy and narrow band imaging for colonic neoplasms: a meta-analysis

AIM

We conducted a meta-analysis to compare the diagnostic test performance of chromoendoscopy and narrow band imaging (NBI) for colonic neoplasms.

METHOD

MEDLINE, EMBASE and the Cochrane Library were searched (1966 to March 2009). Articles were included if: (i) chromoendoscopy or NBI was used, (ii) sensitivity and specificity were reported; (iii) absolute numbers of true-positive, false-positive, true-negative and false-negative results were provided or could be calculated; and (iv) pathology was used as the reference standard. Sensitivity and specificity were pooled using random effects model. Secondary analyses were conducted by limiting the studies in which magnifying endoscopy was used alone as a diagnostic modality, and polyp size and macroscopic appearance of lesions were not considered.

RESULTS

Of 1342 screened articles, 27 met the inclusion criteria. Pooled sensitivity for chromoendoscopy and NBI was 0.94 (95% CI, 0.92-0.95) and 0.94 (0.91-0.97), and specificity was 0.82 (0.77-0.88) and 0.86 (0.83-0.89), respectively. There were no differences in sensitivity (P = 0.99) or specificity (P = 0.54) between the two methods. In the secondary analysis, pooled sensitivity for choromoendoscopy and NBI was 0.93 (95% CI, 0.90-0.97) and 0.96 (0.93-0.99) and specificity was 0.80 (0.73-0.87) and 0.85 (0.78-0.92). respectively. Overall, the pooled false-negative rate was 0.057 (95% CI, 0.040-0.73) for chromoendoscopy and 0.057 (95% CI, 0.028-0.085) for NBI.

CONCLUSION

Chromoendoscopy and NBI had similar diagnostic test characteristics in the assessment of colonic neoplasms; however, the false-negative rate for both methods of 5.7% is an unacceptably high rate and currently therefore, neither method is ready for general use.

A head-to-head comparison of the water vs. air method in patients undergoing screening colonoscopy

BACKGROUND: The water method facilitates colonoscope insertion in unsedated patients. OBJECTIVE: To compare quality indicators in sedated veterans. DESIGN: Performance improvement. SETTING: VA endoscopy unit. PATIENTS: 368 consecutive screening patients. INTERVENTION: Air or water method assignment (high definition colonoscope) was based on the last digit of social security number. MEASUREMENTS: Adenoma detection rate (ADR), cecal intubation rate; intubation and withdrawal times; sedation requirements and external pressure used. RESULTS: ADR was higher with the water method (57.1% vs. 46.1%, p=0.04). After controlling for age, body mass index, smoking, alcohol, withdrawal time and quality of bowel preparation, the odds of detecting an adenoma was 81% higher with the water method (OR 1.81; 95% cI: 1.12-2.90). In the proximal colon ADR was higher with the water method (45.8% vs. 34.6%, p=0.03), including adenomas <10 mm in size (41.8% vs. 31.4%, p=0.04). The water method showed significantly longer cecal intubation time (6.9±0.3 vs. 5.3±0.3 min, p=0.0001); less external pressure used (11.9% vs. 28.3%, p=0.0001); lower need for additional sedation (17.5% vs. 27.2%, p<0.03). LIMITATIONS: Predominance of males, single unblinded endoscopist with high ADR. CONCLUSIONS: The water method is an independent factor associated with significantly higher ADR. Replication by blinded colonoscopist(s) is indicated.

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).

Role of high definition colonoscopy in colorectal adenomatous polyp detection

AIM: To investigate the rates of polyp detection in a mixed risk population using standard definition (SDC) vs high definition colonoscopes (HDC).

METHODS: This was a retrospective cohort comparative study of 3 colonoscopists who each consecutively performed 150 SDC (307, 200 pixel) and 150 HDC (792, 576 pixels) in a community teaching hospital.

RESULTS: A total of 900 colonoscopies were evaluated (mean age 56, 46.8% men), 450 with each resolution. Polyps of any type were detected in 46.0% of patients using SDC and 43.3% with HDC (P = 0.42). There was no significant difference between the overall number of polyps, HDC (397) and SDC (410), detected among all patients examined, (P = 0.73). One or more adenomatous polyps were detected in 24.2% of patients with HDC and 24.9% of patients with SDC colonoscopy (P = 0.82). There was no significant difference between HDC (M = 0.41) and SDC (M = 0.42) regarding adenomatous polyp (P = 0.88) or advanced adenoma (P = 0.56) detection rate among all patients examined.

CONCLUSION: HDC did not improve yield of adenomatous polyp, advanced adenoma or overall polyp detection in a population of individuals with mixed risk for colorectal cancer.

Randomized, controlled trial of standard-definition white-light, high-definition white-light, and narrow-band imaging colonoscopy for the detection of colon polyps and prediction of polyp histology

BACKGROUND

Missing adenomas and the inability to accurately differentiate between polyp histology remain the main limitations of standard-definition white-light (SD-WL) colonoscopy.

OBJECTIVE

To compare the adenoma detection rates of SD-WL with those of high-definition white-light (HD-WL) and narrow-band imaging (NBI) as well as the accuracy of predicting polyp histology.

DESIGN

Multicenter, prospective, randomized, controlled trial.

SETTING

Two academic medical centers in the United States.

PATIENTS

Subjects undergoing screening or surveillance colonoscopy.

INTERVENTION

Subjects were randomized to undergo colonoscopy with one of the following: SD-WL, HD-WL, or NBI.

MAIN OUTCOME MEASUREMENTS

The proportion of subjects detected with adenomas, adenomas detected per subject, and the accuracy of predicting polyp histology real time.

RESULTS

A total of 630 subjects were included. The proportion of subjects with adenomas was 38.6% with SD-WL compared with 45.7% with HD-WL and 46.2% with NBI (P = .17 and P = .14, respectively). Adenomas detected per subject were 0.69 with SD-WL compared with 1.12 with HD-WL and 1.13 with NBI (P = .016 and P = .014, respectively). HD-WL and NBI detected more subjects with flat and right-sided adenomas compared with SD-WL (all P values <.005). NBI had a superior sensitivity (90%) and accuracy (82%) to predict adenomas compared with SD-WL and HD-WL (all P values <.005).

LIMITATIONS

Academic medical centers with experienced endoscopists.

CONCLUSIONS

There was no difference in the proportion of subjects with adenomas detected with SD-WL, HD-WL, and NBI. However, HD-WL and NBI detected significantly more adenomas per subject (>60%) compared with SD-WL. NBI had the highest accuracy in predicting adenomas in real time during colonoscopy. (

CLINICAL TRIAL REGISTRATION NUMBER

NCT 00614770.).

An unmet medical need: advances in endoscopic imaging of colorectal neoplasia

Gastrointestinal cancer is a major public health problem worldwide. Detection of early neoplastic lesions in gastrointestinal tract is essential for cure, because prognosis and survival are related to the size and stage of malignant lesions. Endoscopic screening and treatment of polyps could prevent approximately 80% of colorectal cancer (CRC). However, white-light endoscopy is an imperfect technology since miss rates of up to 25% have been reported and polyps without malignant potential were treated without benefit but with additional costs and risks to the patient. There are several known "human" predictors of an inadequate colonoscopy. These include patient characteristics such as poor bowel preparation, female gender, or inpatient status. Skills of the endoscopists are also an important issue. Therefore, a variety of advanced technologies has been attempted to overcome these issues. These new endoscopic imaging techniques allow a more precise classification of mucosal alterations with selection of patients for invasive therapy or surveillance. Further, molecular and functional imaging techniques could identify novel targets for therapies and new prospects to access response to therapies. However, at the "end of the day" a better endoscopic approach for CRC screening and surveillance depends on a good bowel preparation, a trained endoscopist spending sufficient time on a detailed examination together with an advanced endoscope.

Current status of chromoendoscopy and narrow band imaging in colonoscopy

Colonoscopy, the preferred procedure for colon cancer screening, has well-documented limitations. To improve colonoscopy's effectiveness, augmented endoscopy techniques, such as chromoendoscopy and narrow band imaging (NBI) have been evaluated. Both techniques are inexpensive, safe, and relatively easy to perform. Chromoendoscopy has an increasingly important role in surveillance of IBD, but significant work is needed to determine the optimal staining techniques and mucosal surface pattern analysis before this technique can be incorporated into routine clinical practice. NBI is a much newer technology with far less data. Well-designed prospective randomized controlled trials have failed to identify a benefit of NBI in screening colonoscopy, in surveillance for high-risk populations or as an adjunct for therapeutic procedures.

The water method for aiding colonoscope insertion: the learning curve of an experienced colonoscopist

BACKGROUND: The water method has promising features for colonoscopy but the learning curve to master the technique is unknown. AIMS: To describe the learning phase, and pitfalls of the water method and its impact on procedural outcomes by an experienced colonoscopist. DESIGN: Review of prospectively collected data in a performance improvement project SETTING: endoscopy Unit at a VA medical center PATIENTS: 200 consecutive veterans undergoing colonoscopy METHODS: An experienced colonoscopist examined 4 consecutive groups of 25 patients each using the water method to define the learning curve. Outcomes were compared to a historical cohort (n=100) examined by the same colonoscopist using usual air insufflation. MAIN OUTCOME MEASURES: Intent-to-treat (ITT) cecal intubation rate. RESULTS: ITT cecal intubation rate increased from 76% (first) to 96% (fourth quartile). Cecal intubation time in the first 2 quartiles was significantly longer (8.9±1.0 and 8.2±0.8 min, respectively) than that in the historical cohort (5.8±0.4 min) but decreased and became comparable to control values in the next 2 quartiles (7.2±0.9 and 6.6±0.6 min, respectively). Overall adenoma detection rate as a group (55%), compared favorably to the historical cohort (46%). CONCLUSIONS: The water method is relatively easy to learn for an experienced colonoscopist. Mastery of the method resulted in cecal intubation rate and overall adenoma detection rate meeting quality performance standards.

A head-to-head comparison of the water vs. air method in patients undergoing screening colonoscopy

BACKGROUND: The water method facilitates colonoscope insertion in unsedated patients. OBJECTIVE: To compare quality indicators in sedated veterans. DESIGN: Performance improvement. SETTING: VA endoscopy unit. PATIENTS: 368 consecutive screening patients. INTERVENTION: Air or water method assignment (high definition colonoscope) was based on the last digit of social security number. MEASUREMENTS: Adenoma detection rate (ADR), cecal intubation rate; intubation and withdrawal times; sedation requirements and external pressure used. RESULTS: ADR was higher with the water method (57.1% vs. 46.1%, p=0.04). After controlling for age, body mass index, smoking, alcohol, withdrawal time and quality of bowel preparation, the odds of detecting an adenoma was 81% higher with the water method (OR 1.81; 95% cI: 1.12-2.90). In the proximal colon ADR was higher with the water method (45.8% vs. 34.6%, p=0.03), including adenomas <10 mm in size (41.8% vs. 31.4%, p=0.04). The water method showed significantly longer cecal intubation time (6.9±0.3 vs. 5.3±0.3 min, p=0.0001); less external pressure used (11.9% vs. 28.3%, p=0.0001); lower need for additional sedation (17.5% vs. 27.2%, p<0.03). LIMITATIONS: Predominance of males, single unblinded endoscopist with high ADR. CONCLUSIONS: The water method is an independent factor associated with significantly higher ADR. Replication by blinded colonoscopist(s) is indicated.

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.

Aim to unify the narrow band imaging (NBI) magnifying classification for colorectal tumors: current status in Japan from a summary of the consensus symposium in the 79th Annual Meeting of the Japan Gastroenterological Endoscopy Society

At present, there are many narrow band imaging (NBI) magnifying observation classifications for colorectal tumor in Japan. To internationally standardize the NBI observation criteria, a simple classification system is required. When a colorectal tumor is closely observed using the recent high-resolution videocolonoscope, a pit-like pattern on the tumor can be observed to a certain degree without magnification. In the symposium we could have a consensus that we will name the pit-like pattern as 'surface pattern.' Using the NBI system, the microvessels on the tumor surface can also be recognized to a certain degree. When the NBI system is used, the structure is emphasized, and consequently, the surface pattern can be recognized easily. Recently, an international cooperative group was formed and consists of members from Japan, the USA and Europe, which is named as the Colon Tumor NBI Interest Group. This group has developed a simple category classification (NBI international colorectal endoscopic [NICE] classification), which classifies colorectal tumors into types 1-3 even by closely observing colorectal tumors using a high-resolution videocolonoscope (Validation study is now ongoing by Colon Tumor NBI Interest Group.). The key advantage of this is simplification of the NBI classification. Although the magnifying observation is the best for getting detailed NBI findings, both close observation and magnifying observation using the NICE classification might give almost similar results. Of course the NICE classification can be used more precisely with magnification. In this report we also refer the issues on NBI magnification, which should be solved as early as possible.

An alerting system improves adherence to follow-up recommendations from colonoscopy examinations

BACKGROUND & AIMS

Systems are available to ensure that results of tests are communicated to patients. However, lack of adherence to recommended follow-up evaluation increases risk for adverse health outcomes and medical or legal issues. We tested the effectiveness of a novel follow-up system for patients due for surveillance colonoscopy examinations.

METHODS

Electronic medical records from colonoscopies performed 5 years prior were reviewed to identify individuals due for a repeat surveillance colonoscopy examination. Patients were assigned to groups that received the standard of care or a newly developed follow-up system that included a letter to the primary care provider, 2 letters to the patient, and a telephone call to patients who had not yet scheduled an examination by the procedure due date. The primary end point was the percentage of patients who scheduled or completed the colonoscopy examination within 6 months of the due date. Secondary end points included detection rate for adenomas, sex- and ethnicity-specific follow-up rates, and patient satisfaction.

RESULTS

Of 2609 patient records reviewed, 830 (31.8%) were found to be due for a surveillance colonoscopy examination in the study period. At the conclusion of the study, 241 (44.7%) patients in the intervention arm had procedures scheduled or completed, compared with 66 (22.6%) in the control group (P < .0001). The follow-up system appeared particularly effective among non-white patients; patients reported general satisfaction with the reminder program.

CONCLUSIONS

A simple protocol of letters and a telephone call to patients who are due for colonoscopy examinations significantly improved adherence to endoscopic follow-up recommendations. This work provides justification for the creation of reminder systems to improve patient adherence to medical recommendations.

Implications of Serum 25-Hydroxyvitamin D on the Prevalence of Neoplastic Polyps: A Cross-Sectional Study

Background

Vitamin D is believed to help in the suppression of malignant cells. Epidemiologic studies suggest that there is an association between vitamin D deficiency and an increased risk of colorectal cancer. The primary aim of this study is to determine if the prevalence of neoplastic polyps is inversely related to serum 25-hydroxyvitamin D levels 25(OH)D.

Methods

A prevalence study conducted between April 2009 and October 2009 evaluated 651 patients undergoing colonoscopy in order to determine if an association existed between low 25(OH)D levels and the prevalence of neoplastic colon polyps. Multivariate logistic and linear regression analyses were used to establish an association between 25(OH)D levels and histology of colon polyp with gender, race, age and BMI.

Results

The presence of tubular adenoma, villous adenoma, tubulo-villous adenoma, or malignancies did not differ (P = 0.5) among the stratified 25(OH)D groups (10 ng, 10.1 - 30 ng, > 30 ng). In addition, despite having more African-Americans than Caucasians in the lowest 25(OH)D category (22.7% versus 7.7%), the presence of neoplastic polyps did not differ significantly (P = 0.8) between the categorized racial groups (Caucasian and African-Americans).

Conclusions

Low plasma 25(OH)D levels are not associated with an increased prevalence of neoplastic polyps.

Narrow-band imaging endoscopy with and without magnification in diagnosis of colorectal neoplasia

AIM: To evaluate the diagnostic efficacies of narrow-band imaging (NBI) endoscopy with and without high magnification in distinguishing neoplasia from non-neoplasia colorectal lesions.

METHODS: A total of 118 patients with 123 colorectal lesions examined by NBI endoscopy in the Zhejiang Provincial People’s Hospital from September 2008 to April 2010 were enrolled in this study. These lesions were classified by pit pattern and capillary pattern, and then assessed by histopathology.

RESULTS: Ten lesions not meeting the diagnostic criteria were excuded, the overall diagnostic accuracy of NBI endoscopy in distinguishing neoplasia from non-neoplasia colorectal lesions was 91.2% (103/113), and that of NBI endoscopy with and without high magnification was 93.0% (40/43) and 90.0% (63/70), respectively. Both were significantly higher than that of conventional colonoscopy reported in the literature (P < 0.05), but there was no significant difference between the two groups (P > 0.05).

CONCLUSION: Besides NBI magnifying endoscopy, NBI endoscopy without magnification may also be used to distinguish neoplasia from non-neoplasia colorectal lesions.

Risk factors and diagnosis of flat adenomas of the colon

In addition to histology, size and location, a morphologic description can be ascribed to polyps and adenomas. Traditionally, adenomas have been described as sessile and pedunculated, but it is now accepted that they can also present as flat or even depressed. Although first recognized in 1985, flat adenomas have become more common in Western published literature and in endoscopic reports. The Japanese Research Society Classification describes flat adenomas as lesions with a height that is less than one half of the diameter, while the Paris classification divides polyps into protruding and nonprotruding. The clinical significance of flat adenomas includes their potential malignancy, difficulty in detection and possible role in interval cancers. Serrated polyps represent a subset of polyps that have all the features that make flat lesions clinically important. Due to the relatively recent recognition of these lesions, as well as the technology required to detect them, the prevalence and malignant potential of these lesions in Western patients are still unknown. Finally, the best techniques and equipment for detecting flat polyps are also not established. In this article, we examine the issue of flat polyps and their significance in colorectal cancer screening with regard to prevalence, risk factors and methods for detecting flat polyps.

Wide view and retroview during colonoscopy

Colonoscopy is the best imaging device currently available for the detection of lesions in the large bowel, but may be an imperfect tool against colon cancer. Because recent guidelines for colorectal cancer screening and surveillance depend on whether polyps are found on colonoscopy and on their size, the need to identify all the neoplasia in the colon has assumed greater importance. This article reviews and assesses the latest developments in colonoscopy including wide-angle optics, endoscope caps and hoods, retroflexion and the use of the third eye retroscope.

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.

Autofluorescence imaging with a transparent hood for detection of colorectal neoplasms: a prospective, randomized trial

BACKGROUND

Colonoscopy is one of the most reliable methods for detection of colorectal neoplasms, but conventional colonoscopy can miss some lesions.

OBJECTIVE

To evaluate the efficacy of autofluorescence imaging (AFI) with a transparent hood (TH) for detection of colorectal neoplasms.

DESIGN

A 2 × 2 factorial designed, prospective, randomized, controlled trial.

SETTING

This study was conducted at the Osaka Medical Center for Cancer and Cardiovascular Diseases, a tertiary cancer center.

PATIENTS

A total of 561 patients.

INTERVENTIONS

Patients were allocated to 1 of 4 groups: (1) white light imaging (WLI) alone--colonoscopy using WLI without a TH; (2) WLI+TH--colonoscopy using WLI with a TH; (3) AFI alone--colonoscopy using AFI without a TH; and (4) AFI+TH--colonoscopy using AFI with a TH. Eight colonoscopists used each allocated method.

MAIN OUTCOME MEASUREMENT

The difference in neoplasm detection rate (number of detected neoplasms per patient) between the WLI alone and AFI+TH groups.

RESULTS

Neoplasm detection rate (95% confidence interval) in the AFI+TH group was significantly higher than in the WLI alone group (1.96 [1.50-2.43] vs 1.19 [0.93-1.44]; P = .023, Tukey-Kramer multiple comparison test). Relative detection ratios (95% confidence interval) for polypoid neoplasms based on Poisson regression model were significantly increased by mounting a TH (1.69 [1.34-2.12], P < .001), and relative detection ratios for flat neoplasms were significantly increased by AFI observation (1.83 [1.24-2.71], P = .002).

LIMITATIONS

Open trial performed in single cancer referral center.

CONCLUSION

AFI colonoscopy with a TH detected significantly more colorectal neoplasms than did conventional WLI colonoscopy without a TH.

Live image processing does not increase adenoma detection rate during colonoscopy: a randomized comparison between FICE and conventional imaging (Berlin Colonoscopy Project 5, BECOP-5)

OBJECTIVES

Fujinon intelligent chromoendoscopy (FICE) is a post-processing imaging technique for increasing contrast of mucosa and mucosal lesions that might lead to improvement in colonic adenoma detection during colonoscopy. Previous studies on similar contrast-enhancing techniques as well as on dye staining have yielded variable and conflicting results. This large randomized trial was undertaken to determine whether FICE technology enhances adenoma detection rate (ADR).

METHODS

In a prospective study performed in a multicenter private practice and hospital setting, involving 8 examiners with substantial lifetime experience (>10,000 colonoscopies each), 1,318 patients (men 46.7%, women 53.3%; mean age 59.05 years) were randomly assigned to colonoscopy with either FICE or white light imaging on instrument withdrawal. Of the colonoscopies, 68% were screening and 32% were diagnostic examinations. The primary outcome measure was the ADR (i.e., number of adenomas/total number of patients).

RESULTS

There was no difference between the two groups in terms of general ADR (0.28 in both groups), the total number of adenomas (184 vs. 183), or detection of subgroups of adenomas. The rate of identification of hyperplastic polyps was also the same in both groups (127 vs. 121; P=0.67). The results were the same for both the screening and the diagnostic colonoscopy subgroups. Withdrawal time was the same in both groups (8.4 vs. 8.3 min, P=0.55).

CONCLUSIONS

This large randomized trial could not show any objective advantage of the FICE technique over conventional high-resolution endoscopy in terms of improved ADR.

Computerized virtual chromoendoscopy versus indigo carmine chromoendoscopy combined with magnification for diagnosis of small colorectal lesions: a randomized and prospective study

BACKGROUND AND STUDY AIMS

Magnifying colonoscopy with indigo carmine dye and the analysis of the capillary and the pit patterns by computed virtual chromoendoscopy (Fujinon Intelligent Color Enhancement, FICE) with magnification are effective for the differential diagnosis of neoplastic and non-neoplastic lesions. This study aimed to compare the accuracy of virtual and real chromoendoscopy in differentiating neoplastic and non-neoplastic colorectal lesions.

PATIENTS AND METHODS

A prospective randomized trial of magnification colonoscopy with targeted FICE (Group I - 72 patients/111 lesions) versus magnification colonoscopy with targeted indigo carmine dye (Group II - 72 patients/137 lesions) was performed in consecutive patients with lesions 1 cm or less. Histopathology of the specimens was regarded as the gold standard.

RESULTS

In group I, 86 (77.5%) lesions showed an intense vascular pattern (positive capillary meshwork), of which 80 (93%) were histologically confirmed as adenomas. From 25 lesions with negative capillary meshwork, 23 (92%) were non-neoplastic. Sensitivity, specificity, accuracy, positive and negative predictive values of the capillary meshwork for the differential diagnosis of these lesions was 97.8, 79.3, 92.8, 93 and 92%, respectively. The same parameters for pit pattern analysis by FICE were 92.7, 82.3, 90.1, 93.8 and 80%, respectively. Indigo carmine magnified chromoscopy showed sensitivity, specificity, accuracy, positive and negative predictive values of 97, 88.9, 94.9, 96.1 and 91.4%, respectively in the discrimination between neoplastic and non-neoplastic lesions.

CONCLUSION

Magnified virtual chromoendoscopy is as accurate as indigo carmine magnified chromoendoscopy in distinguishing between neoplastic from non-neoplastic small colorectal lesions.

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.

Comparison of standard vs high-definition, wide-angle colonoscopy for polyp detection: a randomized controlled trial

AIM

We sought to compare the performance of colonoscopy using a high-definition, wide-angle endoscope vs a standard colonoscope for the detection of polyps.

METHOD

A total of 390 patients were prospectively randomized into high-definition colonoscopy group (HD, n = 193) and standard colonoscopy group (SC, n = 197).

RESULTS

Analysis demonstrated that there were significant differences between the two groups, as far as the overall rate of polyps (SC, 1.31 ± 1.90; HD, 1.76 ± 2.31; P = 0.03) and the rate of small hyperplastic polyps (size < 5 mm; SC, 0.10 ± 0.36; HD, 0.25 ± 0.61; P = 0.003) were concerned. No significant differences between the two groups were observed, regarding large polyps (size ≥ 10 mm; SC, 0.39 ± 0.89; HD, 0.48 ± 0.80; P = 0.10), medium polyps (10 mm > size ≥ 5 mm; SC, 0.60 ± 1.46; HD, 0.58 ± 1.25; P = 0.31) and small polyps (size < 5 mm; SC, 0.32 ± 0.86; HD, 0.71 ± 1.65; P = 0.09). Similarly, no significant differences were demonstrated in the detection rate of adenomas and hyperplastic polyps, large adenomas, medium adenomas, small adenomas and large and medium hyperplastic polyps.

CONCLUSION

High-definition colonoscopy led to a significant increase in the polyp detection.

Flat colon polyps: what should radiologists know?

With the recent publication of international computed tomography (CT) colonography standards, which aim to improve quality of examinations, this review informs radiologists about the significance of flat polyps (adenomas and hyperplastic polyps) in colorectal cancer pathways. We describe flat polyp classification systems and propose how flat polyps should be reported to ensure patient management strategies are based on polyp morphology as well as size. Indeed, consistency when describing flat polyps is of increasing importance given the strengthening links between CT colonography and endoscopy.

Characterization of colorectal tumors using narrow-band imaging magnification: combined diagnosis with both pit pattern and microvessel features

OBJECTIVE

We aimed to clarify the clinical usefulness of narrow-band imaging (NBI) magnification for evaluating both pit appearances and microvessel architecture in comparison with evaluation of microvessel architecture alone in invasion depth of colorectal tumors.

MATERIAL AND METHODS

A total of 189 colorectal lesions [37 adenomas, 73 intramucosal to scanty submucosal invasive carcinomas and 79 massive submucosal invasive (SM-m) carcinomas] were analyzed. All lesions showing irregular pit structure were observed by NBI magnifying endoscopy. Based on both pit appearance and microvessel features, lesions were classified into three grades (C1, C2, C3), as described previously. Also, lesions were classified as high or low by microvessel irregularity. Furthermore, the histopathological background and the inter- and intraobserver variability of C subtype were assessed.

RESULTS

The SM-m rate of C1, C2 and C3 was 5.2, 60.5 and 92.7%, respectively. On the other hand, SM-m rate of lesion with mildly and highly irregular vessels was 13.3 and 55.0%, respectively. For the histopathological background, a high percentage of destruction of the glandular orifice, disappearance of the lamina muscularis mucosae and superficial exposure of desmoplastic reaction (DR) were observed in type C3. For C subtype classification of NBI magnification findings, the kappa value for interobserver variability was 0.749, and the kappa value for intraobserver variability was 0.745.

CONCLUSIONS

NBI magnification findings evaluated by both pit appearances and microvessel features (C subtype) showing a good kappa value in variability are more useful in invasion depth diagnosis of colorectal tumor than those evaluated by microvessel features alone.

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.

A prospective randomized study on computed virtual chromoendoscopy versus conventional colonoscopy for the detection of small colorectal adenomas

BACKGROUND

Colonoscopy is considered to be the standard diagnostic test for detecting colonic neoplasia, particularly for small lesions. However, recent publications have suggested that 15-27% of small adenomas might be missed during conventional colonoscopy.

AIMS

To determine whether computed virtual chromoendoscopy (CVC) can improve the detection of small adenomas as compared to conventional colonoscopy.

METHODS

We examined 135 consecutive patients by total colonoscopy and 128 patients were randomized to compare white-light colonoscopy (65 patients) and CVC-mode colonoscopy (63 patients) after the exclusion of seven patients because of poor bowel preparation (n = 4) or other causes (one sigmoid colon cancer, two intestinal tuberculosis).

RESULTS

There were no differences between the patient characteristics for the two study groups, i.e., age, sex, body mass index, quality of bowel preparations, indications for the procedure, conscious sedation, and examination times-both insertion time and withdrawal time. The groups did not differ in the number of patients with all polyps, adenomas, or hyperplastic polyps. In the patients with adenomas, however, there was a significant difference in the detection rate for the patients with small adenomas less than 5 mm in size (P = 0.006).

CONCLUSIONS

Colonoscopy with the CVC mode identified more patients with small colorectal adenomas than conventional white-light colonoscopy. Therefore, CVC might be a supplementary tool aiding the colonoscopist in the detection of small adenomas; however, further studies will need to demonstrate whether these results are reproducible across patients in varied clinical settings.

New endoscopy devices to improve population adherence to colorectal cancer prevention programs

Despite recent advances in medicine, colorectal cancer (CRC) remains one of the greatest hazards for public health worldwide and especially the industrialized world. It has been well documented with concrete data that regular screening colonoscopy aimed at early detection of precancerous polyps can help decrease the incidence of CRC. However, the adherence of the general population to such screening programs has been shown to be lower than that expected, thus allowing CRC to remain a major threat for public health. Various reasons have been suggested to explain the disappointing compliance of the population to CRC screening programs, some of them associated with colonoscopy per se, which is viewed by many people as an unpleasant examination. Governments, medical societies, individual gastroenterologists, as well as the medical industry are working in order to improve endoscopic devices and/or to improve standard colonoscopy. The aim is to improve the acceptance of the population for this method of CRC screening, by providing a painless and reliable examination of the colon. This review focuses on some of the latest improvements in this field.

Polyp surveillance

Surveillance after colonic polypectomy is important to detect and remove missed synchronous polyps and cancers and new metachronous polyps or cancers. The authors review methods of surveillance and the risk of recurrent adenomas and provide surveillance recommendations.

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.

Diagnostic accuracy of pit pattern and vascular pattern analyses in colorectal lesions

BACKGROUND

The aim of this prospective study is to compare the usefulness of magnifying narrow band imaging (NBI) and magnifying chromoendoscopy in the diagnosis of colorectal lesions.

METHODS

The subjects were 1185 patients who underwent a complete colonoscopic examination and endoscopic or surgical treatment, from January 2006 to February 2008. A total of 1473 lesions were evaluated (53 hyperplastic polyps, 1317 adenomas, 103 submucosally invasive cancers). The digital images with NBI or chromoendoscopy were recorded and diagnosed independently from each other by two endoscopists who were blinded to the final pathological diagnosis.

RESULTS

We could differentiate between neoplastic and non-neoplastic lesions with sensitivity of 88.9%, specificity of 98.5% and accuracy of 98.2% according to the vascular pattern. By recognizing an irregular or sparse pattern with NBI, massively invasive submucosal cancer could be diagnosed with the sensitivity and specificity of 94.9% and 76.0%. Using chromoendoscopy, we could differentiate between neoplastic and non-neoplastic lesions with sensitivity of 86.8% and specificity of 99.2%. We were able to differentiate between massively invasive cancers and slightly invasive cancers using the pit patterns with sensitivity of 89.7% and specificity of 88.0%. The specificity was superior to that of NBI colonoscopy.

CONCLUSION

Both NBI and chromoendoscopy can be useful for distinguishing between neoplastic and non-neoplastic lesions. In the diagnosis of submucosal cancer, pit pattern diagnosis was slightly superior to vascular pattern diagnosis. It is desirable to perform chromoendoscopy in addition to NBI for distinguishing between slightly and massively invasive submucosal cancer lesions and determining the treatment.

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.

Surveillance colonoscopy using a transparent hood and image-enhanced endoscopy

Colonoscopists can miss adenomas during colonoscopy screening. A transparent hood attached to the tip of the colonoscope helps detection of colorectal adenomas, but as far as we are aware, there has been no trial indicating its statistically significant effectiveness. Total colonic dye spray might improve the adenoma detection rate but it is complicated and time-consuming for routine clinical usage. Moreover, the efficacy of narrow band imaging for detection of colorectal adenoma is controversial and is still under debate. Autofluorescence imaging (AFI) might be better able to detect flat lesions than white light imaging (WLI), but its ability is influenced easily by the area of the observation. Therefore, we have attached a transparent hood to the tip of an AFI colonoscope during colonoscopy screening in clinical usage. AFI can detect a flat lesion, which is difficult to detect using WLI. A transparent hood can help to detect lesions behind the folds by pushing the colonic fold. We expect that mounting a transparent hood would work complimentary to AFI. Further improvements, including a combination of AFI and a transparent hood, are needed and they would provide optimal surveillance intervals.

Advances in endoscopic imaging of colorectal neoplasia

Colon cancer screening is arguably the most important activity performed by gastroenterologists. Recent decreases in rates of death from colorectal cancer indicate that screening methods such as colonoscopy have a positive impact. There is still room for improvement, however, particularly in prevention of right-sided colon cancer. Practice issues, such as making colonoscopy more comfortable, safer, and less costly, are keys to continued success in cancer prevention. Colonoscopy techniques, technologies, and quality control measures have advanced to improve detection, classification, and removal of early neoplasias. In particular, slow, careful inspection of the colon by gastroenterologists who have been trained in lesion recognition has improved rates of detection of polypoid and flat neoplasias. Image enhancement methods such as chromoendoscopy have greatly improved neoplasia detection in patients with chronic colitis, but are not widely used because they are perceived as inconvenient. More convenient methods, such as "digital" chromoendoscopy, show promise but have had mixed results. Ultra-high magnification systems, including optical magnification and confocal endomicroscopy, can be used during the colonoscopy examination to evaluate small polyps, allowing physicians to make immediate diagnoses and decisions about whether to remove polyps. In patients with inflammatory bowel disease, improved imaging techniques could eliminate the needs for analysis of randomly selected biopsy samples and resection of all (neoplastic and non-neoplastic) polyps. It is important to maintain high standards of quality for colonoscopy examination, detection, and removal of high-risk lesions, as well as to make colon cancer screening more widely accepted and affordable for the entire at-risk population.

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.

Hood-assisted colonoscopy is more effective in detection of colorectal adenomas than narrow-band imaging

BACKGROUND & AIMS

Colonoscopy, using either a transparent retractable extension device or narrow band imaging, is thought to improve colon adenoma detection. We compared the abilities of a transparent retractable extension device and narrow band imaging to detect colorectal adenomas.

METHODS

One hundred and seven patients with colonic adenomas that were detected by traditional colonoscopy were randomly assigned to groups that underwent a second colonoscopy that used either a transparent retractable extension or narrow band imaging; adenomas were removed. The principal outcome parameters were the number, size, shape, and location of adenomas detected. The patients' demographic characteristics, indications for colonoscopy, and cecal intubation times were similar between groups.

RESULTS

Use of the transparent retractable extension resulted in detection of 31% more adenomas than the initial procedure (P < .0001). The majority of newly discovered adenomas were sessile (79%; 26/33) and less than 5 mm in size (73%; 24/33). There was no significant increase in adenoma detection (5%) between first colonoscopy and second colonoscopy using narrow band imaging. Additional adenomas were found in 40.7% of patients that were examined using the transparent hood (22/54) versus 13.2% of those examined using narrow band imaging (7/53) (P = .0028).

CONCLUSIONS

Colonoscopy with a transparent retractable extension significantly improved the adenoma detection rate compared with repeat colonoscopy using narrow band imaging.

Narrow Band Imaging and Autofluorescence Imaging for the Detection and Optical Diagnosis of Colorectal Polyps

Colorectal cancer is the most common cancer in Singapore and polyps which are detected during screening colonoscopy are routinely removed. Conventional white light colonoscopy has a substantial miss-rate for polyps and limited accuracy in differentiating neoplastic from non-neoplastic polyps. Dye-based chromoendoscopy and more recent equipment-based image enhanced endoscopic techniques such as narrow-band imaging (NBI) and autofluorescence imaging (AFI) are promising tools to improve polyp detection and optical diagnosis. Current evidence suggests that NBI may not be superior compared to high definition white-light for polyp detection, but it achieves excellent accuracy in polyp characterisation, approaching that of histopathology. AFI is a wide area scanning modality which functions as a red-flag technique to improve polyp detection, although the evidence is still evolving. The ability to accurately characterise polyps with NBI and AFI will guide the management of polyps and in some cases, avoid unnecessary polypectomy and routine histopathology. This has potential to reduce associated costs and risks of polypectomy, and improves on overall efficiency of screening colonoscopy. The review will discuss the technology, current evidence and the issues relevant to the role of NBI and AFI for the detection and optical diagnosis of polyps in colorectal cancer screening.

Recognition and characterization of small colonic neoplasia with high-definition colonoscopy using i-Scan is as precise as chromoendoscopy

BACKGROUND

The EPKi system (Pentax, Japan) enables resolution above HDTV. Aim of the study was to test the efficacy of HD+ alone and with the new post-processing digital filter i-Scan or chromoendoscopy (Methylene blue 0.1%) in screening for colorectal cancer. We focused on lesions less than 5 mm as a surrogate marker for the optical possibilities of the EPKi system.

METHODS

The last 30 cm of the colon in a screening population were inspected with HD+ alone, in combination with i-Scan (2:1 randomisation) and subsequently with chromoendoscopy. All lesions were characterized and targeted biopsies were performed.

RESULTS

i-Scan augmented in 69 patients the identification of lesions from 176 to 335 (p<0.001) and chromoendoscopy to 646 (p<0.001). The additional lesions were mainly flat (type IIb, 74%), which were only recognized using i-Scan or chromoendoscopy. The amount of neoplasias was not significantly different (HD+: 5, i-Scan: 11, Chromoendoscopy: 11), but all could correctly be predicted using i-Scan or chromoendoscopy.

CONCLUSIONS

HD+ colonoscopy with and without i-Scan unmask a plethora of small lesions but chromoendoscopy can even advance the number. However, i-Scan was able to predict neoplasia as precisely as chromoendoscopy and might shortly replace chromoendoscopy as a more time efficient tool.