Standard White Light Colonoscopy Research Articles

Colonoscopic techniques in polyp detection: An Egyptian study

Introduction and aimsThe polyp detection rate is defined as the percentage of colonoscopies in which one or more polyps are detected, and has been shown to be highly correlated with the adenoma detection rate. The aim of the present study was to evaluate the polyp detection rate at the Endoscopy Unit of the Kasr Al-Ainy Hospital, Cairo University, Egypt, through the i-SCAN, Endocuff, and underwater colonoscopy techniques. Materials and methodsThe study was conducted on 100 Egyptian subjects over 50 years of age. Their polyp detection rate was measured through 4 different colonoscopic techniques. An equal number of patients were divided into 4 groups: i-SCAN, Endocuff, underwater colonoscopy, and controls. The control group was examined using standard white light colonoscopy. The colonoscopy evaluation included the type of agent utilized for bowel preparation, preparation grade, and colonoscopy withdrawal time. ResultsThe general polyp detection rate was 48%. The i-SCAN technique had the highest rate (56%), followed by the underwater (52%) and the Endocuff (48%) techniques. ConclusionThe i-SCAN and underwater colonoscopy techniques produced higher polyp detection rates than the Endocuff-assisted and standard techniques, but with no statistical significance.

Colonoscopic techniques in polyp detection: An Egyptian study.

The polyp detection rate (PDR) is defined as the percentage of colonoscopies in which one or more polyps are detected, and has been shown to be highly correlated with the adenoma detection rate. The aim of the present study was to evaluate the PDR at the Endoscopy Unit of the Kasr Al-Ainy Hospital, Cairo University, Egypt, through the i-SCAN, Endocuff, and underwater colonoscopy techniques. The study was conducted on 100 Egyptian subjects over 50 years of age. Their polyp detection rate was measured through 4 different colonoscopic techniques. An equal number of patients were divided into 4 groups: i-SCAN, Endocuff, underwater colonoscopy, and controls. The control group was examined using standard white light colonoscopy. The colonoscopy evaluation included the type of agent utilized for bowel preparation, preparation grade, and colonoscopy withdrawal time. The general PDR was 48%. The i-SCAN technique had the highest rate (56%), followed by the underwater (52%) and the Endocuff (48%) techniques. The i-SCAN and underwater colonoscopy techniques produced higher PDR than the Endocuff-assisted and standard techniques, but with no statistical significance.

Feasibility and economic assessment of chromocolonoscopy for detection of proximal serrated neoplasia within a population-based colorectal cancer screening programme (CONSCOP): an open-label, randomised controlled non-inferiority trial

Most post-colonoscopy interval colorectal cancers are proximal; serrated polyps are often precursors to these cancers and are considered difficult to detect. We assessed the safety, feasibility, and economic effect of chromocolonoscopy on detection of proximal serrated neoplasia. We did an open-label, multicentre, randomised, controlled non-inferiority trial including patients from Bowel Screening Wales centres. Participants who tested positive for faecal occult blood and who were eligible for and considered fit to have colonoscopy (patients with known cases of polyposis syndromes, Lynch syndrome, and chronic inflammatory disease were excluded) were randomly assigned (1:1; with the use of minimisation, stratified by centre with an 80:20 random element) to either standard white light colonoscopy (standard group) or chromocolonoscopy (indigo carmine dye [0·2%]; chromocolonoscopy group) using a secure, internet-based, computerised, randomisation system that used centralised, dynamic allocation. Participants were followed up for 1 year and data from index colonoscopies and associated clearance procedures were analysed. All proximal polyps were reviewed by an expert pathologist panel. The main outcome on which power was based was time taken to perform the colonoscopy procedure, defined as from the time when the scope was inserted to withdrawal from the anus, assessed in the per-protocol population. The non-inferiority margin was 15 min. This trial is complete and is registered with ClinicalTrials.gov, number NCT01972451. Between Nov 20, 2014, and June 16, 2016, 741 (72%) of 1031 patients screened were eligible and consented: 360 were randomly assigned to white light colonoscopy and 381 to chromocolonoscopy. In the chromocolonoscopy group, the procedure took a mean of 36·8 min (SD 15·0), compared with a mean of 30·6 min (13·7) in the standard group (mean difference 6·3 min [95% CI 4·2-8·4] longer with chromocolonoscopy than in the standard group). The mean difference was within the prespecified non-inferiority margin. Detection rates for proximal serrated lesions were significantly higher in the chromocolonoscopy group than in the control group (45 [12%] of 381 patients vs 23 [6%] of 360 patients; odds ratio 1·96 [95% CI 1·16-3·32]; p=0·012). Serious adverse events (four cases of postpolypectomy bleeding [two in each group], and one case of anxiety and hyperventilation [in the chromocolonoscopy group]), colonoscopy quality measures, comfort scores, and sedation were similar between groups. Chromocolonoscopy is feasible within a population-based colorectal cancer screening programme, is safe, and has significantly increased detection of proximal serrated neoplasia and other polyp types compared with standard colonoscopy. Larger randomised trials of chromocolonoscopy, powered for improved detection of significant serrated polyps and for longer-term follow-up to investigate the effect on reduction of interval cancers within screening populations, are warranted. Health and Care Research Wales (RfPPB-1021).

Colonoscopy and chromoscopy in hereditary colorectal cancer syndromes.

With hereditary colorectal cancer prevention studies it is difficult to demonstrate reduced mortality. Large populations are needed with well characterized genetics followed over a long period of time. Those studies do exist for standard white light colonoscopy surveillance in Lynch syndrome, but not for newer technologies including chromoscopy. For these newer technologies adenoma detection rate becomes the stand-in for mortality, and the assumption is made that surveillance efficacy impacts cancer occurrence. Though well-designed and important work exists in this area, the data do not support firm conclusions regarding the use of chromoscopy in Lynch syndrome.

Increased Detection of Colorectal Polyps in Screening Colonoscopy Using High Definition i-SCAN Compared with Standard White Light.

Background/Aims:The aim of this study was to evaluate the efficacy of high definition (HD) i-SCAN for colorectal polyp detection in screening colonoscopy. Methods:We retrospectively analyzed the records of 501 patients who had undergone screening colonoscopy performed by three endoscopists with either HD i-SCAN (n=149) or standard white light (n=352) from January 2, 2014 through June 30, 2014. Patient information and inter-endoscopist variation as well as polyp number, endoscopic findings, and pathologic characteristics were reviewed.Results:The detection rates of colorectal and neoplastic polyps were significantly higher using HD i-SCAN than standard white light colonoscopy (52% vs. 38.1%, p=0.004 for colorectal polyps; and 37.2% vs. 27.9%, p=0.041 for neoplastic polyps). Analysis of endoscopic findings revealed no difference in detected polyp size between HD i-SCAN and standard white light colonoscopy (4.59±2.35 mm vs. 4.82±2.81 mm, p=0.739), but non-protruding polyps were more commonly detected by i-SCAN than by standard white light colonoscopy (24.6% vs. 13.5%, p=0.007). Conclusions:Colonoscopy using HD i-SCAN had a significantly higher detection rate of colorectal polyps, including neoplastic polyps, because of improved sensitivity for detecting non-protruding lesions.

PTU-080 Calprotectin predicts relapse of ibd even in the presence of a ‘normal’ colonoscopy

Introduction Faecal calprotectin is a sensitive and reliable marker of mucosal inflammation and mucosal healing in IBD. It has always been compared against endoscopic appearance as the presumed gold standard for assessment of disease activity. Several strands of evidence – using magnifying or image-enhanced endoscopy as well as confocal laser endomicroscopy – highlight abnormalities in colonic mucosa reported as ‘normal’ by standard white light colonoscopy (WLC). This may be compounded by the difficulties in bowel preparation in IBD and the non-widespread use of high definition technology (although the latter has not been specifically studied in relation to IBD). We wished to determine whether an elevated FCALP could predict relapse even in the presence of an ostensibly normal WLC. Method As part of a larger study correlating FCALP to histologic assessment of disease activity, retrospective data was collected for consecutive patients with IBD on stable therapy undergoing colonoscopy for disease assessment. FCALP (Buhlmann ELISA) was collected as close as possible (prior) to the colonoscopy. When the colonoscopic appearances were reported as normal (Mayo endoscopic subscore 0 for ulcerative colitis, UC, and SES-CD = 0 for Crohn’s disease, CD), patients were followed to determine if they relapsed, with time to relapse (or last recorded follow-up) taken from the date of colonoscopy. For the purposes of this study, relapse was defined generally as “continuous or worsening intestinal symptoms requiring an escalation in therapy”. Switching between 5ASA classes was not included in this definition unless the specifically stated to be in response to uncontrolled symptoms. Results 46 patients with UC and 37 with CD were identified with the above criteria. Median time between FCALP measurement and colonoscopy was 0.70 (max 2.89) and 0.90 (max 1.5) months respectively. Normal FCALP was detected in 16 patients with UC and 12 with CD. Figures 1 and 2 below show relapse-free survival in those patients with a normal colonoscopy and normal FCALP (<60 mcg/g faeces; green line) compared to those with elevated levels (red line). Median calprotectin in the ‘high’ group was 377 (229–794) in UC and 192 (118–247) in CD. At 12 months, survival proportions were 86% with UC and normal FCALP compared to 34% in those with high FCALP. In CD, these proportions were 50% and 12% respectively. Conclusion Elevated levels of FCALP predict relapse of IBD even in the presence of a macroscopically normal colonoscopy. Disclosure of interest None Declared.

Recent advances to improve the endoscopic detection and differentiation of early colorectal neoplasia.

One of the primary aims of colonoscopy is to detect andresect pre-cancerous lesions, thereby preventing cancerdevelopment and early colorectal cancers, avoiding thegrowth of advanced and deep-infiltrating malignanttumours. Failure to find and remove polyps and early can-cers results in a delayed cancer diagnosis and treatment,with the potential for poor patient outcomes and the riskof litigation [1]. In recent years, industry has made manyefforts to improve the technology to enhance the perfor-mance of endoscopic examination: many of these innova-tions are included under the term ‘augmentedendoscopy’. Augmented endoscopy includes topical dyes[2,3], optical filtering [4,5], zoom-magnification [6,7]and allows for various analyses of gastro-intestinal lesions,such as minute structure of crypts on the mucosal surfaceand superficial micro-vessels. This kind of enhancedendoscopy provides new tools for identifying the abnor-malities in the size, density, and shape of crypts andvessels in either the normal colon or a tumour lesion.Today, colonoscopy is a universally accepted methodfor colorectal cancer screening and diagnosis [8]. En-doscopists may, however, miss up to 6% of advancedadenomas (≥10 mm in size) or cancer and as many as26–30% of all adenomas when using standard white-light colonoscopy [9], probably because of the locationof the lesion, the skill of the endoscopist [10] and theimage contrast of the endoscopic picture. Augmentedendoscopy, enhancing the endoscopic appearances ofcolon lesions, has the potential to improve detectionand differentiation of colon neoplasms from otherlesions [11]. Clinical trials testing the usefulness ofaugmented endoscopy for the diagnosis of colonneoplasia show conflicting results [12]. This may berelated to the limitations of each technology and varia-tion in the diagnostic skill of the participants. There-fore, as reported by Fujiya and Kohgo, ‘...two factorsrelated to the usefulness of these novel technologiesneed to be evaluated: at which step(s) is that technologyapplicable for the diagnosis of colon neoplasms (detec-tion, differentiation, or staging) and by what level(s) ofendoscopists (experts or less experienced endoscopists)can the technology be used ...’ [13].Technology alone, however, is not enough to ensureoptimal results and to achieve the best outcome. Allvariables affecting rates of detection by the endoscopistand the endoscopic method used are important. Theseinclude the operator’s experience, bowel preparation,examination technique and the use of instruments ordevices able to increase visual identification.

Tu1525 Sessile Serrated Adenomas Are Common in IBD Surveillance Colonoscopy and Better Detected by Chromoendoscopy and Virtual Chromoendoscopy

In IBD sessile or flat neoplastic lesions including sessile serrated adenomas/polyps (SSAs) are difficult to detect by standard white light colonoscopy. The dye spraying chromoendoscopy is now the new standard of care for detection of such neoplastic lesions. We aim to establish whether dye spraying chromoendoscopy may be replaced by electronic virtual chromoendoscopy, as the latter is more convenient, less expensive and reversible. We further aim to characterize the serrated adenomas possibly associated with IBD which are currently difficult to detect.

In Vivo Diagnostic Accuracy of High-Resolution Microendoscopy in Differentiating Neoplastic from Non-Neoplastic Colorectal Polyps: A Prospective Study

High-resolution microendoscopy (HRME) is a low-cost, "optical biopsy" technology that allows for subcellular imaging. The purpose of this study was to determine the in vivo diagnostic accuracy of the HRME for the differentiation of neoplastic from non-neoplastic colorectal polyps and compare it to that of high-definition white-light endoscopy (WLE) with histopathology as the gold standard. Three endoscopists prospectively detected a total of 171 polyps from 94 patients that were then imaged by HRME and classified in real-time as neoplastic (adenomatous, cancer) or non-neoplastic (normal, hyperplastic, inflammatory). HRME had a significantly higher accuracy (94%), specificity (95%), and positive predictive value (PPV, 87%) for the determination of neoplastic colorectal polyps compared with WLE (65%, 39%, and 55%, respectively). When looking at small colorectal polyps (less than 10 mm), HRME continued to significantly outperform WLE in terms of accuracy (95% vs. 64%), specificity (98% vs. 40%) and PPV (92% vs. 55%). These trends continued when evaluating diminutive polyps (less than 5 mm) as HRME's accuracy (95%), specificity (98%), and PPV (93%) were all significantly greater than their WLE counterparts (62%, 41%, and 53%, respectively). In conclusion, this in vivo study demonstrates that HRME can be a very effective modality in the differentiation of neoplastic and non-neoplastic colorectal polyps. A combination of standard white-light colonoscopy for polyp detection and HRME for polyp classification has the potential to truly allow the endoscopist to selectively determine which lesions can be left in situ, which lesions can simply be discarded, and which lesions need formal histopathologic analysis.

Sa1594 Endoscopic Screening of Proximal Colon Adenomas: Conventional Imaging Versus Chromoendoscopy With Indigo Carmine Dye

The adenoma-carcinoma sequence developed is accepted in principle for colorectal cancer. Small proximal adenomas (above the splenic flexure) are commonly missed during screening colonoscopy. The aim of our study was to assess the detection rate of proximal colon adenomas by comparing chromocolonoscopy with standard white light colonoscopy.

Meta-analysis of narrow-band imaging versus conventional colonoscopy for adenoma detection

At colonoscopy, missed adenomas have been well documented at approximately 22%. The challenge is in reducing this miss rate. Narrow-band imaging (NBI) has been extensively evaluated in prospective, randomized, controlled studies for polyp detection. Sample-size calculations show us that these studies may be underpowered, and hence a meta-analysis is required. Our aim was to determine whether use of NBI enhances the detection of adenomas. Meta-analyses were conducted of 7 studies using NBI for adenoma detection rate. MEDLINE, Embase, PubMed, and Cochrane databases were searched by using a combination of the following terms: "colonoscopy," "NBI," and "electronic chromoendoscopy." There was a total of 2936 patients in the NBI studies. Prospective, randomized trials of NBI versus standard white-light colonoscopy (WLC) were conducted. We excluded spray chromoendoscopy studies and studies of inflammatory bowel disease and polyposis syndromes. Adenoma and polyp detection rates and the number of polyps and adenomas detected per person. There was no statistically significant difference in the overall adenoma detection rate with the use of NBI or WLC (36% vs 34%; P = .413 [relative risk 1.06; 95% CI, 0.97-1.16]), and there was no statistically significant difference in polyp detection rate by using NBI or WLC (37% vs 35%; P = .289 [relative risk 1.22; 95% CI, 0.85-1.76]). When the number of adenomas and polyps per patient was analyzed, no significant difference was found between NBI and WLC (0.645 vs 0.59; P = .105 and 0.373 vs 0.348; P = .139 [weighted mean difference 0.19; 95% CI, ∞0.06 to 0.44], respectively). Variability in NBI studies can reduce the accuracy of this analysis. NBI did not increase adenoma or polyp detection rates.

A comparison of high definition-image enhanced colonoscopy and standard white-light colonoscopy for colorectal polyp detection

Colonoscopy is widely used to detect and remove precancerous polyps, but fails to detect some polyps. Recent studies evaluating different image-enhanced methods have revealed conflicting results. The efficacy of colonoscopy imaging with simultaneous use of commercially available improvements, including high definition narrow band imaging (HD-NBI), and monochromatic charge-coupled device (CCD) video, was compared with a widely used standard definition white light (SDWL) colonoscopy system for detecting colorectal polyps. The primary aim was to determine whether the combination of image-enhanced colonoscopy systems resulted in fewer missed polyps compared with conventional colonoscopy. In a randomized controlled trial (Clinicaltrials.gov. study number NCT00825292) patients having routine screening and surveillance underwent tandem colonoscopies with SDWL and image-enhanced (HD-NBI) colonoscopy. The main outcome measurement was the per-polyp false-negative ("miss") rate. Secondary outcomes were adenoma miss rate, and per-patient polyp and adenoma miss rates. 100 patients were randomized and 96 were included in the analysis. In total, 177 polyps were detected; of these, 72 (41 %) were adenomatous. Polyp and adenoma miss rates for SDWL colonoscopy were 57 % (60/105) and 49 % (19/39); those for image-enhanced colonoscopy were 31 % (22/72) and 27 % (9/33) (P = 0.005 and P = 0.036 for polyps and adenomas, respectively). Image-enhanced and SDWL approaches had similar per-patient miss rates for polyps (6/35 vs. 9/32, P = 0.27) and adenomas (4/22 vs. 8/20, P = 0.11). Utilization of multiple recent improvements in image-enhanced colonoscopy was associated with a reduced miss rate for all polyps and for adenomatous polyps. It is not known which individual feature or combination of image-enhancement features led to the improvement.

Cancer surveillance strategies in ulcerative colitis

The risk of colorectal cancer is increased in patients with long-standing ulcerative colitis. Traditional surveillance has centered around regular standard white-light colonoscopy, with multiple biopsies aimed at detecting dysplasia or the identification of early cancer. This has resulted in only a modest reduction in cancer incidence and mortality. A better understanding of disease risk factors may allow endoscopic resources to be more focused on patients at higher risk. In addition, advanced endoscopic techniques have the potential to improve dysplasia detection, minimize the need for routine biopsies, and allow for the removal of dysplastic lesions, avoiding the need for surgery. Techniques such as magnification colonoscopy, chromoendoscopy, narrow band imaging, autofluorescence, and confocal endomicroscopy may all have a role to play in improving the benefits of endoscopic surveillance. Revised endoscopic surveillance strategies are proposed, incorporating aspects of risk stratification, a well-established practice in noncolitis-related colorectal cancer screening, and some of these new technologies.

High-Definition Colonoscopy Detects Colorectal Polyps at a Higher Rate Than Standard White-Light Colonoscopy

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. 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. 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). 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.

High Accuracy of Narrow Band Imaging Without Magnification for the Real-Time Characterization of Polyp Histology and Its Comparison With High-Definition White Light Colonoscopy: A Prospective Study

Standard white light colonoscopy has limited ability to differentiate between polyp types (adenomatous vs. hyperplastic). Narrow band imaging (NBI) highlights the superficial mucosal/vascular patterns on polyps and may facilitate real-time characterization of polyp histology. The aim of this study was to prospectively evaluate and compare the diagnostic characteristics of high-definition white light colonoscopy (HDWL) and NBI without magnification in the real-time prediction of polyp histology (adenomatous vs. hyperplastic) by evaluating the surface mucosal and vascular patterns. We conducted a prospective comparative study in a tertiary referral center. A total of 100 patients referred for screening or surveillance colonoscopy were prospectively enrolled and underwent colonoscopy using a high-definition colonoscope with NBI capability. Every polyp detected was initially evaluated with HDWL followed by NBI for the presence of surface mucosal/vascular patterns. Based on these patterns, polyp histology was predicted by both modalities. The main outcome measurements were: (i) diagnostic characteristics of HDWL and NBI in predicting polyp histology and (ii) impact of polyp size and learning effect (first half of study vs. second half) on the ability of NBI to predict adenomas. A total of 236 polyps were detected in 100 patients-143 adenomas, 77 hyperplastic, and 16 others. Surface patterns (type A: hyperplastic; type B: adenomatous) were recognized in all polyps with NBI (100%) compared to 45% with HDWL. For predicting adenomas, NBI had a significantly higher sensitivity and greater accuracy (96 and 93% respectively) compared with HDWL (38 and 61% respectively) (all P<0.0001). Although the accuracy of NBI for predicting adenomas improved with increasing polyp size (< or =5 mm; 6-9 mm; > or =10 mm) and in the second half compared with the first half of the study, these differences were not statistically significant. Using a simple surface mucosal/vascular pattern classification, NBI without magnification was highly accurate and significantly superior to HDWL for the real-time prediction of adenomas.

Chromocolonoscopy detects more adenomas than white light colonoscopy or narrow band imaging colonoscopy in hereditary nonpolyposis colorectal cancer screening

Individuals carrying germline mutations in one of the genes responsible for hereditary nonpolyposis colon cancer (HNPCC) have a lifetime risk of up to 80 % of developing colorectal cancer. As there is evidence for a higher incidence of flat adenomatous precursors and because an accelerated adenoma-carcinoma sequence has been postulated for these patients, early detection of these lesions is essential. It was the aim of the present study to assess the detection rate of polypoid lesions by comparing chromocolonoscopy with standard white light colonoscopy and narrow-band imaging (NBI) colonoscopy. 109 patients were included (98 with a functionally relevant mutation in a mismatch repair gene, 11 fulfilling the strict Amsterdam criteria). In 47 patients, standard colonoscopy was followed by chromocolonoscopy with indigo carmine. In 62 patients, NBI was performed first followed by chromocolonoscopy. A total of 128 hyperplastic and 52 adenomatous lesions were detected. In the first series, 0.5 lesions/patient were identified by standard colonoscopy and 1.5 lesions/patient by chromocolonoscopy ( P < 0.001). In the second series, 0.7 lesions/patient were detected by NBI colonoscopy and 1.8 lesions/patient by chromocolonoscopy ( P = 0.01). At least one adenoma was detected in 15 % of patients by both standard and NBI colonoscopy compared with 28 % of patients by chromocolonoscopy. According to this study, chromocolonoscopy detects significantly more hyperplastic and, in particular, adenomatous lesions than standard white light colonoscopy or NBI.

Narrow Band Imaging Without High Magnification to Differentiate Polyps During Real-Time Colonoscopy: Improvement with Experience

Background: There is no widely-adopted, easily applied method for distinguishing between adenomatous and non-adenomatous polyps during real-time colonoscopy. This results in the needless removal of many non-adenomatous polyps which increases costs and risk to the patient. Aims: To compare standard broad-band white light (WL) with narrow band imaging (NBI) for the differentiation of colorectal polyps during in vivo, real-time colonoscopy and to assess whether a learning curve exists for NBI. Methods: 302 patients undergoing routine colonoscopy by four experienced colonoscopists were recruited prospectively between August, 2006 and July, 2007 . Standard WL colonoscopy was performed with Olympus 180 series high-definition colonoscopes. When each polyp was found, it was first examined by WL (1.5x; total magnification up to 70x) and diagnosed endoscopically as adenomatous or non-adenomatous, and then reexamined at the same magnification with NBI. Modified Kudo pit pattern and vascular color intensity (VCI) were recorded, and histology was predicted. Each polyp was then removed and sent for histologic evaluation. Endoscopists were given feedback every 2 weeks regarding the accuracy of their predictions. Results: 268 polyps were found in 132 patients; 50% were non-adenomatous (hyperplastic, abberant crypt foci, lymphoglandular complex, sessile serrated polyp, serrated polyp NOS, other). Diagnostic accuracy was 81% with NBI and 78% for WL (p = 0.35). Accuracies were significantly better for larger polyps and those with polypoid shape but there was no difference between NBI and WL. NBI performed better than WL in diagnosing adenomas (sensitivity 81% vs. 69%, p < 0.05), particularly those < 5mm (75% vs. 60%, p < 0.05). The accuracy was lowest for sessile serrated polyps (47% vs. 86% for all other non-adenomatous polyps, p < 0.001). Non-adenomatous polyps were more likely to have a “light” VCI compared with adenomas (71% vs. 29%, p < 0.001). During the second half of the study, NBI accuracy for differentiating polyps improved from 74% to 87% and outperformed an unchanged WL accuracy of 79% (p < 0.05). The improvement was most pronounced for adenomas (72% to 89%, p < 0.05). Additionally, when endoscopists changed their diagnosis after NBI examination, they were correct 56% of the time in the first half of the study compared with 80% in the second half. Conclusions: There is a learning curve associated with NBI when using it to differentiate colorectal polyps in vivo. With experience, NBI becomes more accurate than WL. Further refinements of an NBI pit pattern classification and vascular color intensity scale are needed.

Narrow-band imaging colonoscopy—a pilot feasibility study for the detection of polyps and correlation of surface patterns with polyp histologic diagnosis

Colonoscopy is the preferred screening method for colorectal cancer. However, it has a substantial miss rate for colon polyps, and several techniques have been attempted to improve this limitation. Narrow-band imaging (NBI) is a novel technology that enhances the visualization of surface mucosal and vascular patterns. The aim of this study was to determine the detection rate of additional polyps by NBI after removal of polyps visualized by standard white light colonoscopy (WLC) and to correlate the surface mucosal and vascular patterns with polyp histologic diagnosis. This was a prospective pilot feasibility study. Kansas City Veterans Affairs Medical Center. Subjects referred for screening colonoscopy were prospectively enrolled. Subjects underwent colonoscopy after enrollment. After intubation of the cecum, colonic segments were sequentially examined, initially with WLC with removal of polyps followed by re-examination of the same segment with NBI. Additional polyps seen with NBI were photographed for their surface patterns and then removed. The total number of polyps visualized by WLC and NBI was calculated and the surface patterns were then correlated with polyp histologic features. Forty patients were enrolled in the study, all men, 32 white. The mean age was 62 years. A total of 72 polyps were detected by WLC (43 tubular adenoma, 28 hyperplastic polyps), whereas NBI detected an additional 51 polyps, of which 29 were tubular adenomas and 22 were hyperplastic. Five different surface/vascular patterns were observed: fine capillary network with absent mucosal pattern, circular pattern with dots, round/oval pattern, tubular pattern, and gyrus pattern. The sensitivity, specificity, and overall accuracy of the first two patterns for hyperplastic polyps were 86%, 96%, and 92%, respectively, and of the latter three patterns for tubular adenomas were 96%, 86%, and 92%, respectively. This pilot study demonstrates the feasibility of polyp detection and histologic correlation with NBI. These findings need to be confirmed in future randomized controlled trials.