Total colonic dye-spray increases the detection of diminutive adenomas during routine colonoscopy: a randomized controlled trial

What is the accuracy of autofluorescence imaging in identifying non-polypoid colorectal neoplastic lesions when reviewed by trainees? A pilot study

BACKGROUND AND AIM

Non-polypoid colorectal neoplasms are difficult to identify using conventional white light (WL) colonoscopy. The aim of the present pilot study was to compare an autofluorescence imaging (AFI) system with conventional WL colonoscopy for the identification of non-polypoid neoplasms by trainees in a colonoscopic observational situation.

METHODS

We selected clear images with both AFI and WL in the same field taken by experts at the National Cancer Center Hospital, Tokyo, from December 2009 to November 2010. One hundred and eighty sets of images (137 non-polypoid neoplasms and 43 without neoplasm) were selected. The images were reviewed by two trainees without AFI experience. After attending a short educational lecture on the AFI system, the reviewers determined the presence of lesions in the randomly arranged images. The accuracy of AFI and WL for identifying non-polypoid neoplasms by trainees was assessed.

RESULTS

The sensitivity and specificity for identifying non-polypoid neoplasms by trainees was not significantly different between AFI and WL. However, the specificity tended to be lower in AFI images than in WL images.

CONCLUSIONS

False-positive results tended to be more frequent for the AFI images than for the WL images. Further improvements in the technology and resolution are necessary for the AFI system to be useful for the detection of colorectal neoplasms. At present, clinical application of the AFI system may require more extensive structured training to improve its accuracy in the identification of non-polypoid colorectal neoplasms.

Adenoma detection in patients undergoing a comprehensive colonoscopy screening

Measures shown to improve the adenoma detection during colonoscopy (excellent bowel preparation, cecal intubation, cap fitted colonoscope to examine behind folds, patient position change to optimize colon distention, trained endoscopy team focusing on detection of subtle flat lesions, and incorporation of optimum endoscopic examination with adequate withdrawal time) are applicable to clinical practice and, if incorporated are projected to facilitate comprehensive colonoscopy screening program for colon cancer prevention. To determine adenoma and serrated polyp detection rate under conditions designed to optimize quality parameters for comprehensive screening colonoscopy. Retrospective analysis of data obtained from a comprehensive colon cancer screening program designed to optimize quality parameters. Academic medical center. Three hundred and forty-three patients between the ages of 50 years and 75 years who underwent first screening colonoscopy between 2009 and 2011 among 535 consecutive patients undergoing colonoscopy. Comprehensive colonoscopy screening program was utilized to screen all patients. Cecal intubation was successful in 98.8% of patients. The Boston Bowel Preparation Scale for quality of colonoscopy was 8.97 (95% confidence interval [CI]; 8.94, 9.00). The rate of adenoma detection was 60% and serrated lesion (defined as serrated adenomas or hyperplastic polyps proximal to the splenic flexure) detection was 23%. The rate of precancerous lesion detection (adenomas and serrated lesions) was 66%. The mean number of adenomas per screening procedure was 1.4 (1.2, 1.6) and the mean number of precancerous lesions (adenomas or serrated lesions) per screening procedure was 1.6 (1.4, 1.8). Retrospective study and single endoscopist experience. A comprehensive colonoscopy screening program results in high-quality screening with high detection of adenomas, advanced adenomas, serrated adenomas, and multiple adenomas.

Indications, stains and techniques in chromoendoscopy

Early detection of malignancies within the gastrointestinal tract is essential to improve the prognosis and outcome of affected patients. However, conventional white light endoscopy has a miss rate of up to 25% for gastrointestinal pathology, specifically in the context of small and flat lesions within the colon. Chromoendoscopy and other advanced imaging techniques aim at facilitating the visualization and detection of neoplastic lesions and have been applied throughout the gastrointestinal tract. Chromoendoscopy, particularly in combination with magnifying endoscopy has significantly improved means to detect neoplastic lesions in the gastrointestinal mucosa, particularly in ulcerative colitis and Crohn's colitis. In addition, chromoendoscopy is beneficial in the upper gastrointestinal tract, especially when evaluating Barrett's oesophagus (BO) for the presence of dysplasia. Furthermore, it also improves characterization, differentiation and diagnosis of endoscopically detected suspicious lesions, and helps to delineate the extent of neoplastic lesions that may be amenable to endoscopic resection. This review discusses the dyes, indications and advanced endoscopic imaging methods used in various chromoendoscopic techniques, and presents a critical overview of the existing evidence supporting their use in current practice with a particular emphasis on the role in inflammatory bowel disease and BO.

Nurse observation during colonoscopy increases polyp detection: a randomized prospective study

OBJECTIVES

To determine whether a second observer during colonoscopy increases adenoma detection.

METHODS

Consecutive patients undergoing screening colonoscopy were prospectively randomized to routine colonoscopy or physician and nurse observation during withdrawal.

RESULTS

Of 502 patients, 249 were randomized to routine colonoscopy, and 253 to physician plus nurse observation during withdrawal. A total of 592 polyps were detected, 40 identified by the endoscopy nurse only. With nurse observation, 1.32 polyps and 0.82 adenomas were found per colonoscopy, vs. 1.03 polyps and 0.64 adenomas in the routine group, demonstrating a 1.29-fold and a 1.28-fold increase in the average number of polyps and of adenomas detected, respectively. The overall adenoma detection rate (ADR) was 44.1%, with trends toward increased ADR and all-polyp detection rate with nurse observation.

CONCLUSIONS

Nurse observation during colonoscopy resulted in an increase in the number of polyps and adenomas found per colonoscopy, along with a trend toward improved overall ADR and all-polyp detection rate.

A randomized, controlled trial of narrow-band imaging vs high-definition white light for adenoma detection in patients at high risk of adenomas

AIM

The study aimed to investigate whether narrow-band imaging (NBI) can enhance adenoma detection in patients at high risk for adenomas compared with high-definition white-light endoscopy (WLE). High risk was defined as three or more adenomas at last colonoscopy, history of colorectal cancer and positive faecal occult blood test.

METHOD

Two hundred and fourteen patients were randomized 1:1 to examination with NBI or WLE. The primary outcome measure was the proportion of patients with at least one adenoma detected. Secondary outcomes included total adenomas and polyps, flat adenomas, nonadenomatous polyps, advanced adenomas and patients with three or five or more adenomas. A post hoc analysis to examine the effect of endoscopist and bowel preparation was performed.

RESULTS

There was no significant difference in the proportion of patients with at least one adenoma: NBI 73%vs WLE 66%, odds ratio 1.40 (95% CI 0.78-2.52), P = 0.26. There was no significant difference for any secondary outcome measure except for the number of flat adenomas which was significantly greater with NBI [comparison ratio 2.66 (95% CI 1.52-4.63), P = 0.001]. Post hoc analysis indicated that one of three endoscopists performed significantly better for adenoma detection with NBI than WLE [comparison ratio 1.92 (95% CI 1.07-3.44), P = 0.03]. Good bowel preparation was associated with significantly improved adenoma detection with NBI [comparison ratio 1.55 (95% CI 1.01-2.22), P = 0.04] but not with fair preparation.

CONCLUSION

Overall NBI did not improve detection compared with WLE in a group of patients at high risk for colorectal adenomas, but specific subgroups might benefit.

The impact of narrow band imaging for colon polyp detection: a multicenter randomized controlled trial by tandem colonoscopy

BACKGROUND

Previous studies have yielded conflicting results on the adenoma detection rate with narrow band imaging (NBI) compared with white light imaging (WLI). To overcome the confounding factors of these studies, we aimed to evaluate the colonic adenoma detection rate with primary NBI versus that with primary WLI by using consistent NBI system, endoscope, and imaging settings, and experienced colonoscopists.

METHODS

In this multicenter prospective trial, 813 patients were randomized to undergo high-definition, tandem colonoscopy in the right colon with either NBI followed by WLI (NBI-WLI group) or WLI followed by NBI (WLI-NBI group). The NBI settings were fixed at surface structure enhancement level A-5 and adaptive index of hemoglobin color enhancement level 3. All detected polyps were resected or biopsied for histopathological analysis. The primary and secondary outcome measures were the adenoma detection rates and miss rates, respectively, with primary imaging.

RESULTS

The NBI-WLI and WLI-NBI groups comprised 389 and 393 patients, respectively, who met the inclusion criteria. The groups did not differ significantly in age, gender, institution, indication for colonoscopy, bowel preparation, or observation time. The adenoma detection rates of primary NBI and WLI were 42.3 and 42.5 %, respectively [difference not significant (NS)]. The adenoma miss rate was significantly less with primary NBI than with primary WLI (21.3 vs. 27.8 %; p = 0.03).

CONCLUSIONS

NBI does not improve the adenoma detection rate during primary colonoscopy; however, it has a lower miss rate for adenoma lesions in the proximal colon than WLI.

Back-to-back comparison of auto-fluorescence imaging (AFI) versus high resolution white light colonoscopy for adenoma detection

Background

Some patients under close colonoscopic surveillance still develop colorectal cancer, thus suggesting the overlook of colorectal adenoma by endoscopists. AFI detects colorectal adenoma as a clear magenta, therefore the efficacy of AFI is expected to improve the detection ability of colorectal adenoma. The aim of this study is to determine the efficacy of AFI in detecting colorectal adenoma.

Methods

This study enrolled 88 patients who underwent colonoscopy at Asahikawa Medical University and Kushiro Medical Association Hospital. A randomly selected colonoscopist first observed the sigmoid colon and rectum with conventional high resolution endosopy (HRE). Then the colonoscopist changed the mode to AFI and handed to the scope to another colonoscopist who knew no information about the HRE. Then the second colonoscopist observed the sigmoid colon and rectum. Each colonoscopist separately recorded the findings. The detection rate, miss rate and procedural time were assessed in prospective manner.

Results

The detection rate of flat and depressed adenoma, but not elevated adenoma, by AFI is significantly higher than that by HRE. In less-experienced endoscopists, AFI dramatically increased the detection rate (30.3%) and reduced miss rate (0%) of colorectal adenoma in comparison to those of HRE (7.7%, 50.0%), but not for experienced endoscopists. The procedural time of HRE was significantly shorter than that of AFI.

Conclusions

AFI increased the detection rate and reduced the miss rate of flat and depressed adenomas. These advantages of AFI were limited to less-experienced endoscopists because experienced endoscopists exhibited a substantially high detection rate for colorectal adenoma with HRE.

Enteroscopy: Advances in diagnostic imaging

Routine endoscopic imaging of the small bowel is performed with videoendoscopic white light technology. However, currently there are many new methods that improve our visual acuity when evaluating the small bowel mucosa. These methods are collectively called "advanced endoscopic imaging". These imaging methods include high-definition white light endoscopy, standard and dye-less or "virtual" chromoendoscopy, magnification endoscopy and confocal laser endomicroscopy. Regardless of the method used to image the small bowel the endosocopist needs to pay attention to detail and focus on three essential aspects: a) the shape of the lesion, b) the superficial mucosal detail (i.e. "pit pattern") and c) the submucosal vascular pattern. This review describes advances in the endoscopic imaging methods to study the small bowel.

Narrow band imaging for detection of dysplasia in colitis: a randomized controlled trial

OBJECTIVES

In ulcerative colitis surveillance, chromoendoscopy improves dysplasia detection 3 – 5-fold compared with white light endoscopy (WLE). The aim of this study was to investigate whether narrow band imaging (NBI) can improve dysplasia detection compared with WLE.

METHODS

This was a randomized, parallel-group trial. A total of 220 patients were needed to be recruited to detect a threefold increase in dysplasia detection. In all, 112 patients with long-standing ulcerative colitis were randomized to colonoscopic extubation with NBI (56) or WLE (56) (1:1 ratio) at two tertiary endoscopy units in the United Kingdom. Targeted biopsies of suspicious areas and quadrantic random biopsies every 10 cm were taken in both groups. The primary outcome measure was the proportion of patients with at least one area of dysplasia detected. In a prespecified mid-point analysis, the criteria for trial discontinuation were met and the trial was stopped and analyzed at this point.

RESULTS

There was no difference in the primary outcome between the two groups, with 5 patients having at least one dysplastic lesion in each group (odds ratio (OR) 1.00, 95 % confidence interval (95 % CI) 0.27 – 3.67, P = 1.00). This remained unchanged when adjusted for other variables (OR 0.69, 95 % CI 0.16 – 2.96, P = 0.62). Overall, dysplasia detection was 9 % in each arm. Yield of dysplasia from random nontargeted biopsies was 1 / 2,707 (0.04 % ).

CONCLUSIONS

Overall, in this multicenter parallel-group trial, there was no difference in dysplasia detection when using NBI compared with high-definition WLE colonoscopy. Random background biopsies were ineffective in detecting dysplasia.

Serrated polyposis syndrome: Molecular, pathological and clinical aspects

Hyperplastic polyps have traditionally been considered not to have malignant potential. New pathological classification of serrated polyps and recent discoveries about the serrated pathway of carcinogenesis have revolutionized the concepts and revitalized the research in this area. Until recently, it has been thought that most colorectal cancers arise from conventional adenomas via the traditional tumor suppressor pathway initiated by a mutation of the APC gene, but it has been found that this pathway accounts for only approximately 70%-80% of colorectal cancer (CRC) cases. The majority of the remaining colorectal cancer cases follow an alternative pathway leading to CpG island methylator phenotype carcinoma with BRAF mutation and with or without microsatellite instability. The mechanism of carcinomas arising from this alternative pathway seems to begin with an activating mutation of the BRAF oncogene. Serrated polyposis syndrome is a relatively rare condition characterized by multiple and/or large serrated polyps of the colon. Clinical characteristics, etiology and relationship of serrated polyposis syndrome to CRC have not been clarified yet. Patients with this syndrome show a high risk of CRC and both sporadic and hereditary cases have been described. Clinical criteria have been used for diagnosis and frequent colonoscopy surveillance should be performed in order to prevent colorectal cancer. In this review, we try to gather new insights into the molecular pathogenesis of serrated polyps in order to understand their possible clinical implications and to make an approach to the management of this syndrome.

Detectability of colon polyp using computed virtual chromoendoscopy with flexible spectral imaging color enhancement

The aim of this pilot study was to assess the feasibility of using computed virtual chromoendoscopy with the flexible spectral imaging color enhancement (FICE) for colon neoplasia screening. A modified back-to-back colonoscopy using FICE and white light in the right-sided colon was conducted prospectively for the consecutive patients attending for the postoperative (sigmoidectomy or anterior resection) follow-up colonoscopy. Histopathology of detected lesions was confirmed by evaluation of endoscopic resection or biopsy specimens. One-hundred and two patients were enrolled, and 100 patients (61 males and mean age 63 years) were finally analyzed. The total number of polyps detected by FICE and white light colonoscopy was 65 and 45, respectively. The miss rate for all polyps with FICE (24%) was significantly less than that with white light (46%) (P = 0.03). Colonoscopy using FICE could beneficially enhance the detection of neoplastic lesions in the right-sided colon compared to white light colonoscopy.

High colonoscopic prevalence of proximal colon serrated polyps in average-risk men and women

BACKGROUND

Proximal colon serrated polyps likely contribute to the decreased protection of colonoscopy against right-sided colorectal cancer.

OBJECTIVE

To estimate the prevalence and extrapolated detection rate of proximal serrated polyps at screening colonoscopy.

DESIGN

Retrospective study.

PATIENTS

The study involved secondary analyses that used two databases. The first includes screening colonoscopies performed by 15 attending gastroenterologists at two academic endoscopy units between 2000 and 2009. The second includes average-risk patients who had previously participated in a randomized trial comparing high-definition chromocolonoscopy and white-light colonoscopy.

MAIN OUTCOME MEASUREMENTS

Prevalence of proximal serrated polyps found by the highest-level detectors and proximal serrated polyp detection rates corresponding to adenoma detection rates of 25% in men and 15% in women, respectively.

RESULTS

We analyzed 6681 procedures from the first database. Mean (± standard deviation) detection rates for adenomas and proximal serrated polyps were 38% ± 7.8% (range 17%-47%) and 13% ± 4.8% (1%-18%), respectively. There was a significant correlation between detection rates for adenomas and proximal serrated polyps for men (R = 0.71; P = .003) and women (R = 0.73; P = .002). Adenoma detection rates of 25% for men and 15% for women both corresponded to a detection rate of 4.5% for proximal serrated polyps. The prevalence of proximal serrated polyps found by the highest-level detector was 18%. The corresponding rate derived from the high-definition screening colonoscopy database was 20%.

LIMITATIONS

Retrospective study.

CONCLUSION

The prevalence of proximal colon serrated polyps in average-risk patients undergoing screening colonoscopy is higher than previously reported. An extrapolated proximal serrated polyp detection rate of 5% is suggested for average-risk men and women.

Serrated polyposis syndrome and the role of serrated polyps in colorectal cancer development

SUMMARY Serrated polyposis syndrome is characterized by the presence of multiple colorectal serrated polyps and is associated with an increased colorectal cancer risk. The mixture of distinct precursor lesion types and malignancies in serrated polyposis syndrome provides a unique model to study the recently proposed serrated neoplasia pathway. This pathway involves the progression of serrated polyps, that is, hyperplastic polyps, sessile serrated adenoma/polyps and/or traditional serrated adenomas, to colorectal cancer. The early genetic events of this route, as currently identified, are BRAF or KRAS mutations and an enhanced CPG island methylation status of multiple genes. There is evidence to suggest that a proportion of sporadic colorectal cancers originate from serrated polyps, which encompass molecular sequences of events such as hypermethylation of different genes and BRAF mutations. This review discusses the characteristics and clinical relevance of serrated polyps and provides an overview of the clinical aspects and treatment of serrated polyposis syndrome.

NBI and NBI Combined with Magnifying Colonoscopy

Although magnifying chromoendoscopy had been a reliable diagnostic tool, narrow-band imaging (NBI) has been developed in Japan since 1999 and has now replaced the major role of chromoendoscopy because of its convenience and simplicity. In this paper, we principally describe the efficacy of magnifying chromoendoscopy and magnifying colonoscopy with NBI for detection, histological prediction, estimation of the depth of early colorectal cancer, and future prospects. Although some meta-analyses have concluded that NBI is not superior to white light imaging for detection of adenomatous polyps in screening colonoscopy, NBI with magnification colonoscopy is useful for histological prediction, or for estimating the depth of invasion. To standardize these diagnostic strategies, we will focus on the NBI International Colorectal Endoscopic (NICE) classification proposed for use by endoscopists with or without a magnifying endoscope. However, more prospective research is needed to prove that this classification can be applied with satisfactory availability, feasibility, and reliability. In the future, NBI might contribute to the evaluation of real-time histological prediction during colonoscopy, which has substantial benefits for both reducing the risk of polypectomy and saving the cost of histological evaluation by resecting and discarding diminutive adenomatous polyps (resect and discard strategy).

A morphologic analysis of sessile serrated polyps observed during routine colonoscopy (with video)

BACKGROUND

Proximal colorectal cancer may arise from sessile serrated polyps (SSPs), which are often inconspicuous during colonoscopy. The gross morphologic characteristics of SSPs have not been systematically described, and this omission may contribute to colonoscopists overlooking them.

OBJECTIVES

To analyze the gross morphologic characteristics of SSPs detected during routine colonoscopy.

DESIGN

Retrospective analysis of high-resolution endoscopic video clips depicting SSPs in situ.

SETTING

Outpatient gastroenterology practice.

PATIENTS

A total of 124 subjects undergoing surveillance or screening colonoscopy after split-dose bowel preparation.

INTERVENTIONS

Analysis of 158 SSPs performed by using validated descriptors.

MAIN OUTCOME MEASUREMENTS

The prevalence of morphologic characteristics related to polyp shape, color, and texture.

RESULTS

A total of 158 SSPs were studied. For 7 visual descriptors, a κ coefficient of ≥ 0.7 was achieved, indicating good to excellent intraobserver agreement. The most prevalent visual descriptors were the presence of a mucous cap (63.9%), rim of debris or bubbles (51.9%), alteration of the contour of a fold (37.3%), and interruption of the underlying mucosal vascular pattern (32.3%). The most common "sentinel signs" were the presence of a mucous cap and alteration of the contour of a mucosal fold (each 24.6%), rim of debris or bubbles (21.7%), and a dome-shaped protuberance (20.3%). When comparing SSPs with adenomatous polyps, the frequencies of 5 of 7 morphologic characteristics and the distribution of sentinel signs differed (P < .01).

LIMITATIONS

Single-site, retrospective analysis.

CONCLUSIONS

SSPs exhibit distinct, variable morphologic characteristics. Many do not display classic features such as a mucous cap. Enhanced appreciation of these morphologic characteristics may improve SSP detection and thereby colorectal cancer prevention.

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.

Participation by experienced endoscopy nurses increases the detection rate of colon polyps during a screening colonoscopy: a multicenter, prospective, randomized study

BACKGROUND

No reported prospective, randomized study has evaluated the impact of an endoscopy nurse participating as a second observer during colonoscopy.

OBJECTIVE

To determine whether the participation of an endoscopy nurse enhanced the polyp detection rate (PDR) and adenoma detection rate (ADR) during screening colonoscopy.

DESIGN

Multicenter, prospective, randomized study.

SETTING

Academic hospitals.

PATIENTS

A total of 844 consecutive patients undergoing screening colonoscopy.

INTERVENTIONS

Single observation by colonoscopist or dual observation by colonoscopist and endoscopy nurse during colonoscope withdrawal.

MAIN OUTCOME MEASUREMENTS

PDR and ADR.

RESULTS

No significant difference in patient demographic data, adequacy of bowel preparation, or mean withdrawal time was observed between the 2 groups. In total, 1153 polyps, including 762 adenomas, were detected in 791 patients. Seven nonpolypoid, depressed neoplastic lesions (0-IIc or combined types) were only detected in the dual observation group. A multivariate analysis revealed that experienced (≥ 2 years) endoscopy nurse participation significantly increased the PDR and ADR compared with those in the single observation group by a colonoscopist alone (adjusted odds ratio [OR] 1.58 [95% CI, 1.07-2.32]; adjusted OR 1.47 [95% CI, 1.01-2.12], respectively). Additionally, the PDR was significantly higher in the dual-observation group with fellows (<500 colonoscopies) and an experienced endoscopy nurse versus that in the single observation group (adjusted OR 2.07 [95% CI, 1.15-3.74]). There was no significant benefit of experienced nurse participation in the subgroup with experienced colonoscopists.

LIMITATIONS

Absence of colonoscopist blinding.

CONCLUSIONS

Experienced endoscopy nurse participation increased the PDR and ADR during screening colonoscopy. However, the benefit of participation by experienced nurses appears to be exclusively with inexperienced colonoscopists.

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.

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.

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.

Prospective Case Study on Characterization of Colorectal Adenomas Comparing AFI with NBI

Aim. Compare the characterization ability of AFI and NBI for colorectal adenomas. Methods. We prospectively enrolled 58 patients with 89 colorectal adenomas detected by white light colonoscopy. Such lesions were subsequently observed with both AFI and NBI and then treated by endoscopic resection. With respect to the 89 lesions, 3 experienced endoscopists retrospectively evaluated the visualization quality of the AFI and NBI images in a blind manner using a three-tier scale based on excellent, fair, and poor criteria. Results. There were 54, 31, and 4 lesions considered as excellent, fair, and poor visualization, respectively, using AFI in comparison to 53, 19, and 17 lesions, respectively, with NBI. The percentage of excellent and fair visualization lesions was 95.5% with AFI and 80.9% with NBI (P < .01). Conclusion. This study indicated that AFI may be more effective for the characterization of colorectal adenomas because of better visualization of such lesions compared to NBI.

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.

Advances in endoscopic visualization of colorectal polyps

AIM

Conventional white-light endoscopy is currently the gold standard for the detection and treatment of colorectal polyps. However, up to a fifth of polyps may be missed on initial examination, especially flat and small mucosal lesions. This study reviews the literature reporting on the use of new advances in endoscopic visualization.

METHOD

Literature searches were performed on PubMed using the terms 'chromoendoscopy', 'narrow-band imaging' (NBI), 'autofluorescence imaging' (AFI), 'Fujinon Intelligent Colour Enhancement' (FICE), 'i-Scan colonoscopy', 'zoom colonoscopy' and 'confocal laser endomicroscopy' (CLE). We focused on systematic reviews, national guidelines and randomized controlled trials written in English. Studies were assessed for methodological quality using QUADAS. Prospective studies assessing new technology were also reviewed. Further publications were identified from reference lists.

RESULTS

Chromoendoscopy increases the detection of neoplastic polyps compared with conventional colonoscopy. NBI avoids the use of additional dyes and enhances the vascular network of capillaries surrounding the crypts, increasing the adenoma detection rate and the ability to distinguish between neoplastic and non-neoplastic lesions. FICE, AFI and i-Scan are new developments that improve tissue contrast. Zoom endoscopy may be combined with different modalities to help further characterize colonic lesions. CLE provides live in vivo high-resolution optical sections of tissue and may be particularly useful in the surveillance of patients with long-standing ulcerative colitis, reducing the number of random biopsies.

CONCLUSION

Although there is mounting evidence that these new technologies are superior to conventional endoscopy, current guidelines are limited. Further large-scale randomized controlled trials comparing these modalities in different patient subpopulations are warranted.

The clinical significance of serrated polyps

Colorectal cancer (CRC) is a heterogeneous disorder than arises via multiple distinct pathways, such as the serrated pathway, in which serrated polyps (including variants of hyperplastic polyps) are the precursor lesions. Approximately 15-20% of all CRCs arise via the serrated pathway, and these serrated carcinomas are clinically, morphologically, and molecularly distinct from conventional CRCs. The prevention of serrated carcinomas represents an important clinical challenge. Gastroenterologists need to recognize and remove potential precursor lesions and implement a post-polypectomy surveillance program when appropriate. This article focuses on the characteristics and significance of clinically relevant serrated polyps and addresses implications for CRC prevention practices.

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.

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.

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.

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.

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.

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.

Non-polypoid colorectal neoplasms are relatively common worldwide

Flat adenomas are found commonly at colonoscopy throughout the world. Similarly, small, flat submucosally invasive cancers have been described worldwide but are relatively rare, accounting for 5% to 10% of all cancers detected at colonoscopy. Although there appears to be no difference in frequency of non-polypoid colorectal neoplasms between East and West, considerable variation has been reported by individual studies, probably because of lack of consistency when defining a flat lesion. Flat elevated lesions are the most common type of flat lesion and do not appear to have a greatly increased risk of harboring invasive malignancy; however, flat lesions with depression have a significant risk of malignancy and are probably the precursor lesions for most small, flat, or ulcerating cancers.

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.

Relationship of non-polypoid colorectal neoplasms to quality of colonoscopy

Colonoscopy is a dominant modality for colorectal cancer prevention in average-risk patients aged 50 years and older. Non-polypoid colorectal neoplasms (NP-CRNs) are likely a significant contributing factor to interval colorectal cancers because they have a higher prevalence in Western populations than previously thought, are more difficult to detect visually with conventional colonoscopy, and are more likely to contain advanced histology than polypoid neoplasms, regardless of size. The accurate identification and complete removal of NP-CRNs is thus an integral part of high-quality colonoscopy, and a critical component of the ongoing efforts to make colorectal cancer screening programs widely available, effective, and accepted by patients. In this article, the authors examine the quality indicators for colonoscopy, present the reasons for interval cancers, and discuss the relation between NP-CRNs and quality colonoscopy.

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 chromocolonoscopy vs. high-definition white light colonoscopy for average-risk colorectal cancer screening

OBJECTIVES

Flat and depressed colon neoplasms are an increasingly recognized precursor for colorectal cancer (CRC) in Western populations. High-definition chromoscopy is used to increase the yield of colonoscopy for flat and depressed neoplasms; however, its role in average-risk patients undergoing routine screening remains uncertain.

METHODS

Average-risk patients referred for screening colonoscopy at four U.S. medical centers were randomized to high-definition chromocolonoscopy or high-definition white light colonoscopy. The primary outcomes, patients with at least one adenoma and the number of adenomas per patient, were compared between the two groups. The secondary outcome was patients with flat or depressed neoplasms, as defined by the Paris classification.

RESULTS

A total of 660 patients were randomized (chromocolonoscopy: 321, white light: 339). Overall, the mean number of adenomas per patient was 1.2+/-2.1, the mean number of flat polyps per patient was 1.4+/-1.9, and the mean number of flat adenomas per patient was 0.5+/-1.0. The number of patients with at least one adenoma (55.5% vs. 48.4%, absolute difference 7.1%, 95% confidence interval (-0.5% to 14.7%), P=0.07), and the number of adenomas per patient (1.3+/-2.4 vs. 1.1+/-1.8, P=0.07) were marginally higher in the chromocolonoscopy group. There were no significant differences in the number of advanced adenomas per patient (0.06+/-0.37 vs. 0.04+/-0.25, P=0.3) and the number of advanced adenomas<10 mm per patient (0.02+/-0.26 vs. 0.01+/-0.14, P=0.4). Two invasive cancers were found, one in each group; neither was a flat neoplasm. Chromocolonoscopy detected significantly more flat adenomas per patient (0.6+/-1.2 vs. 0.4+/-0.9, P=0.01), adenomas<5 mm in diameter per patient (0.8+/-1.3 vs. 0.7+/-1.1, P=0.03), and non-neoplastic lesions per patient (1.8+/-2.3 vs. 1.0+/-1.3, P<0.0001).

CONCLUSIONS

High-definition chromocolonoscopy marginally increased overall adenoma detection, and yielded a modest increase in flat adenoma and small adenoma detection, compared with high-definition white light colonoscopy. The yield for advanced neoplasms was similar for the two methods. Our findings do not support the routine use of high-definition chromocolonoscopy for CRC screening in average-risk patients. The high adenoma detection rates observed in this study may be due to the high-definition technology used in both groups.

Extent of prevalence and size of flat neoplasms in a heterogeneous population undergoing routine colorectal cancer screening

BACKGROUND

The importance of identifying flat colorectal neoplasms is increasingly appreciated, although the extent of prevalence of these lesions in a general population is not known.

OBJECTIVE

To determine the extent of prevalence of flat neoplasms in a diverse population undergoing routine endoscopic screening for colorectal cancer.

DESIGN

Patients referred to the Colorectal Cancer Screening Clinic over a 12-month period (n = 642).

RESULTS

The patient population was 56% African American and 21% Caucasian; with a mean age of 59 + or - 9 years. Flat neoplasms were detected in 5.5% of all patients, similar to that reported elsewhere, with extent of prevalence being similar regardless of gender or race. Average size of flat neoplasms was of 2.8 + or - 2.3 mm (range 1-20 mm). However, there was no evidence of advanced pathology in any of the flat neoplasms identified.

CONCLUSIONS

Flat neoplasms are common but may not be associated with advanced pathology in a population undergoing routine screening.

Prevalence of nonpolypoid colorectal neoplasms in symptomatic patients scheduled for colonoscopy: a study with total colonic chromoscopy

OBJECTIVES

(i) To determine the prevalence of nonpolypoid colorectal neoplasms (NP-CRNs) in a prospective cohort of patients of a Mediterranean area; (ii) to compare the characteristics of NP-CRNs with those of polypoid adenomas, focusing on the rate of high-grade dysplasia (HGD) and carcinoma; (iii) to evaluate the characteristics of patients harboring NP-CRNs versus patients with protruding adenomas (P-CRNs).

PATIENTS AND METHODS

A prospective, cross-sectional observational study was made in which consecutive unselected patients were scheduled for colonoscopy and pancolonic chromoendoscopy. The Paris Classification of Superficial Neoplastic Lesions was used to classify the detected lesions, and the revised Vienna criteria were applied to describe the grade of dysplasia. All examinations were performed by the same endoscopist, and all samples were reviewed by the same pathologist.

RESULTS

A total of 290 patients were included, and 613 neoplasms were detected-26% of them being NP-CRNs. The prevalence of NP-CRNs was 34.1% [95% confidence interval (CI): 28.8%-39.7%]. The proportion of HGD or carcinoma in NP-CRNs was 2.5% (95% CI: 0.8%-5.9%), versus 2.9% in P-CRNs (95% CI: 1.6%-4.7%). Size larger than 10 mm [odds ratio: 22.7 (95% CI: 5.2-99.2)] and a pedunculated morphology [odds ratio: 5.7 (95% CI: 1.3-24.3)] were related to the presence of HGD or carcinoma. A relationship between increased size and HGD or carcinoma was found for all morphologies. Patients harboring only NP-CRNs and patients harboring only P-CRNs were similar for all the variables collected.

CONCLUSIONS

NP-CRNs have a high prevalence in our region, but show a proportion of HGD and carcinoma similar to that seen in P-CRNs. No patient variable is predictive of the presence of a NP-CRN.

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.