Narrow-band versus white-light high definition television endoscopic imaging for screening colonoscopy: a prospective randomized trial

Short turn radius colonoscope in an anatomical model: Retroflexed withdrawal and detection of hidden polyps

AIM: To evaluate the new RetroView™ colonoscope and compare its ability to detect simulated polyps “hidden” behind colonic folds with that of a conventional colonoscope, utilizing anatomic colon models.

METHODS: Three anatomic colon models were prepared, with twelve simulated polyps “hidden” behind haustral folds and five placed in easily viewed locations in each model. Five blinded endoscopists examined two colon models in random order with the conventional or RetroView™ colonoscope, utilizing standard withdrawal technique. The third colon model was then examined with the RetroView™ colonoscope withdrawn initially in retroflexion and then in standard withdrawal. Polyp detection rates during standard and retroflexed withdrawal of the conventional and RetroView™ colonoscopes were determined. Polyp detection rates for combined standard and retroflexed withdrawal (combination withdrawal) with the RetroView™ colonoscope were also determined.

RESULTS: For hidden polyps, retroflexed withdrawal using the RetroView™ colonoscope detected more polyps than the conventional colonoscope in standard withdrawal (85% vs 12%, P = 0.0001). For hidden polyps, combination withdrawal with the RetroView™ colonoscope detected more polyps than the conventional colonoscope in standard withdrawal (93% vs 12%, P≤ 0.0001). The RetroView™ colonoscope in “combination withdrawal” was superior to other methods in detecting all (hidden + easily visible) polyps, with successful detection of 80 of 85 polyps (94%) compared to 28 (32%) polyps detected by the conventional colonoscope in standard withdrawal (P < 0.0001) and 67 (79%) polyps detected by the RetroView™ colonoscope in retroflexed withdrawal alone (P < 0.01). Continuous withdrawal of the colonoscope through the colon model while retroflexed was achieved by all endoscopists. In a post-test survey, four out of five colonoscopists reported that manipulation of the colonoscope was easy or very easy.

CONCLUSION: In simulated testing, the RetroView™ colonoscope increased detection of hidden polyps. Combining standard withdrawal with retroflexed withdrawal may become the new paradigm for “complete screening colonoscopy”.

Finding sessile serrated adenomas: is it possible to identify them during conventional colonoscopy?

BACKGROUND AND AIM

Proximal colorectal cancer may arise from sessile serrated adenomas (SSAs). Recognition of these lesions during colonoscopy can optimize the endoscopic approach. We aimed to identify specific endoscopic features of SSA with conventional colonoscopy.

METHODS

Patients undergoing screening colonoscopies from January 2011 to September 2012, in whom colonic polyps were found, were prospectively included in our study. Polyp morphology, location, polyp pit pattern (Kudo classification), and other previously reported features of SSA were evaluated. Histological examination was conducted independently by two pathologists. Multivariate analysis was performed to identify independent predictors of SSA.

RESULTS

A total of 272 patients were included, and 440 polyps were evaluated (1.6 polyps per patient). Thirty-four polyps (8%) were SSA, 135 (31%) hyperplastic, and 249 (56%) adenomas. The most prevalent endoscopic features of SSA were right-side location (94%), type II Kudo pit pattern (91%), mucus cap (41%), flat morphology (29%) and red-colored surface (26%). Multivariate analysis revealed that flat morphology (p = 0.002, OR = 3.81 CI 1.53-9.09), red-colored surface (p < 0.001, OR = 12.97 CI 4.43-37.69), right-side location (p < 0.001, OR = 22.21 CI 5.09-135.94) and mucus cap (p < 0.001, OR 8.77 CI 3.76-20.44) were independent predictors of SSA.

CONCLUSION

We were able to identify specific features of SSA during conventional colonoscopy, which may help to identify, and therefore to optimize the endoscopic approach of these lesions.

Narrow band imaging vs. high definition colonoscopy for detection of colorectal adenomas in patients with positive faecal occult blood test: a randomised trial

BACKGROUND

The impact of narrow band imaging in improving the adenoma detection rate in a screening scenario is still unclear.

AIM

To evaluate whether narrow band imaging compared with high definition white light colonoscopy can enhance the adenoma detection rate during screening colonoscopy.

METHODS

Consecutive patients presenting for screening colonoscopy were included into this study and were randomly assigned to the narrow band imaging group (Group 1) or standard colonoscopy group (Group 2). Primary end point was the adenoma detection rate and secondary aim was the detection rate of advanced adenomas.

RESULTS

Overall, 117 patients were allocated to Group 1 and 120 to Group 2. Both the adenoma detection rate and the detection rate of advanced adenomas were not significantly different between the two groups (respectively, 52.1% vs. 55%, RR=0.95, 95% CI 0.75-1.20; 32.5% vs. 44.2%, RR=0.74, 95% CI 0.53-1.02). No significant difference between the proportions of polypoid and flat adenomas was found. Male gender, no prior history of screening, and endoscopist's adenoma detection rate were independent predictive factors of higher advanced adenoma detection rate.

CONCLUSIONS

In a screening scenario, narrow band imaging did not improve the adenoma nor advanced adenoma detection rates compared to high definition white light colonoscopy.

Usefulness of narrow-band imaging with dual-focus magnification for differential diagnosis of small colorectal polyps

BACKGROUND

Many authors have already reported the usefulness of narrow-band imaging (NBI) for the differential diagnosis of non-neoplastic and neoplastic colorectal lesions. However, it is not clear whether magnification is required for differential diagnosis. The aim of this prospective study was to clarify the clinical usefulness of a newly developed NBI system with a dual focus function (dual-focus NBI) compared with conventional white-light imaging (WLI) and NBI without magnification for distinguishing between non-neoplastic and neoplastic lesions.

PATIENTS AND METHODS

Thirty-seven consecutive patients who underwent screening colonoscopy with the novel system between July and December 2013 were analyzed. Patients with polyps >10 mm and those with polyps previously evaluated by histologic examination or colonoscopy were excluded. Lesions were diagnosed in real time with WLI, NBI without magnification, and dual-focus NBI, and then excised endoscopically. Each diagnosis was compared to that in the final histopathology reports. The primary endpoint was the diagnostic accuracy and the confidence level assigned to each modality by the endoscopists. The secondary endpoint was the differentiation ability according to the size of the lesion (≤5 and 6-10 mm).

RESULTS

In all, 100 lesions including 76 adenomatous polyps and 24 hyperplastic polyps were analyzed in 37 patients. The overall diagnostic accuracy, sensitivity, and specificity for differentiating adenomatous from hyperplastic polyps were 87.0, 89.5, and 79.2 % for WLI, 93.0, 94.7, and 87.5 % for NBI without magnification, and 94.0, 96.1, and 87.5 % for dual-focus NBI, respectively. The level of confidence was significantly different between dual-focus NBI and WLI and NBI without magnification for diminutive (≤5 mm) lesions (p < 0.001 and p < 0.01).

CONCLUSION

Dual-focus NBI is especially useful for differential diagnosis of diminutive colorectal lesions.

Image-enhanced endoscopy is critical in the surveillance of patients with colonic IBD

Cancer risk in patients with inflammatory bowel disease (IBD) involving the colon is high and increases with time. The quality and efficacy of colonoscopic surveillance is variable. Chromoendoscopy with targeted biopsies is superior to standard white light endoscopy with random biopsies. Although commonly practiced, the technique of random colonic biopsies has poor yield for dysplasia and has little clinical consequence. Studies have shown a limited role for electronic-based image-enhanced endoscopy, including narrow band imaging, in detecting IBD dysplasia. Efforts should focus on the dissemination of the technique of chromoendoscopy in routine clinical practice through training and quality metrics.

Experience of the endoscopist increases detection rates of smaller size and higher histological grade polyps

BACKGROUND

Adenoma and polyp detection rates (ADR and PDR, respectively) are important indicators of endoscopy quality, particularly in colorectal carcinoma screening.

OBJECTIVE

To assess the influence of the endoscopist's experience on the ADR and PDR.

PATIENTS AND METHODS

In this study, 9635 colonoscopies were screened during a 5-year period. Only 5738 were finally analyzed due to exclusion criteria. The endoscopists were separated in three groups of experience according to the number of colonoscopies performed in the past (yearly and total). The number of polyps and adenomas, as well as the size and histology of these polyps were recorded.

RESULTS

The ADR and PDR were similar regardless of the experience of the endoscopist, but those with more experience clearly found more polyps of less than 10 mm (P = 0.01) and of less than 3 mm (P < 0.0001). Most of the differences were due to a higher number of flat polyps detected by the experienced group. This study also shows that more experienced endoscopists detect adenomas with more advanced histology (P < 0.0001).

CONCLUSION

Even though the ADR and PDR are similar in all groups of endoscopists, the less experienced endoscopists could be missing some of the smaller polyps, sometimes with more advanced histology.

State of the art in advanced endoscopic imaging for the detection and evaluation of dysplasia and early cancer of the gastrointestinal tract

Ideally, endoscopists should be able to detect, characterize, and confirm the nature of a lesion at the bedside, minimizing uncertainties and targeting biopsies and resections only where necessary. However, under conventional white-light inspection – at present, the sole established technique available to most of humanity – premalignant conditions and early cancers can frequently escape detection. In recent years, a range of innovative techniques have entered the endoscopic arena due to their ability to enhance the contrast of diseased tissue regions beyond what is inherently possible with standard white-light endoscopy equipment. The aim of this review is to provide an overview of the state-of-the-art advanced endoscopic imaging techniques available for clinical use that are impacting the way precancerous and neoplastic lesions of the gastrointestinal tract are currently detected and characterized at endoscopy. The basic instrumentation and the physics behind each method, followed by the most influential clinical experience, are described. High-definition endoscopy, with or without optical magnification, has contributed to higher detection rates compared with white-light endoscopy alone and has now replaced ordinary equipment in daily practice. Contrast-enhancement techniques, whether dye-based or computed, have been combined with white-light endoscopy to further improve its accuracy, but histology is still required to clarify the diagnosis. Optical microscopy techniques such as confocal laser endomicroscopy and endocytoscopy enable in vivo histology during endoscopy; however, although of invaluable assistance for tissue characterization, they have not yet made transition between research and clinical use. It is still unknown which approach or combination of techniques offers the best potential. The optimal method will entail the ability to survey wide areas of tissue in concert with the ability to obtain the degree of detailed information provided by microscopic techniques. In this respect, the challenging combination of autofluorescence imaging and confocal endomicroscopy seems promising, and further research is awaited.

Comparison of detection and miss rates of narrow band imaging, flexible spectral imaging chromoendoscopy and white light at screening colonoscopy: a randomised controlled back-to-back study

OBJECTIVE

Virtual chromoendoscopy (CE) is expected to enhance adenoma yield and reduce variation in performance between colonoscopists. This study aimed to compare the efficacy of narrow band imaging (NBI), flexible spectral imaging CE (FICE) and white light (WL) colonoscopy and their impact for less experienced endoscopists.

METHODS

We performed a randomised tandem colonoscopy trial controlling for withdrawal time and bowel preparation. Average-risk adults undergoing screening colonoscopy were enrolled and randomly assigned to first withdrawal with one of the three imaging modalities (NBI (NBI-WL group), FICE (FICE-WL group) and WL (WL-WL group)). Eight colonoscopists were categorised into expert and non-expert subgroups.

RESULTS

1650 subjects (mean age 51.4 years, 63.9% men) were included (550 in each group). Compared with WL, neither NBI nor FICE increased the mean number of adenomas detected per patient (0.37 vs 0.35 and 0.36; p=0.591) or the percentage of patients with adenoma (25.3% vs 24.5% and 23.6%; p=0.753). For all three modalities, expert subgroups had higher yields of adenomas than non-expert subgroups. Learning curves were observed only for non-expert subgroups with all three modalities. The percentage of missed adenomas did not differ between the three groups (20.8% by WL vs 22.9% by NBI and 26.0% by FICE, p=0.300) and was not affected by endoscopists' expertise.

CONCLUSIONS

Neither NBI nor FICE improved adenoma detection or miss rates, with no difference in diagnostic efficacy between the two systems. Virtual CE had no additional benefits over WL for non-experts.

CLINICAL TRIAL REGISTRATION NUMBER

KCT0000570.

Endoscopic innovations to increase the adenoma detection rate during colonoscopy

Up to a quarter of polyps and adenomas are missed during colonoscopy due to poor visualization behind folds and the inner curves of flexures, and the presence of flat lesions that are difficult to detect. These numbers may however be conservative because they mainly come from back-to-back studies performed with standard colonoscopes, which are unable to visualize the entire mucosal surface. In the past several years, new endoscopic techniques have been introduced to improve the detection of polyps and adenomas. The introduction of high definition colonoscopes and visual image enhancement technologies have been suggested to lead to better recognition of flat and small lesions, but the absolute increase in diagnostic yield seems limited. Cap assisted colonoscopy and water-exchange colonoscopy are methods to facilitate cecal intubation and increase patients comfort, but show only a marginal or no benefit on polyp and adenoma detection. Retroflexion is routinely used in the rectum for the inspection of the dentate line, but withdrawal in retroflexion in the colon is in general not recommended due to the risk of perforation. In contrast, colonoscopy with the Third-Eye Retroscope^® may result in considerable lower miss rates compared to standard colonoscopy, but this technique is not practical in case of polypectomy and is more time consuming. The recently introduced Full Spectrum Endoscopy™ colonoscopes maintains the technical capabilities of standard colonoscopes and provides a much wider view of 330 degrees compared to the 170 degrees with standard colonoscopes. Remarkable lower adenoma miss rates with this new technique were recently demonstrated in the first randomized study. Nonetheless, more studies are required to determine the exact additional diagnostic yield in clinical practice. Optimizing the efficacy of colorectal cancer screening and surveillance requires high definition colonoscopes with improved virtual chromoendoscopy technology that visualize the whole colon mucosa while maintaining optimal washing, suction and therapeutic capabilities, and keeping the procedural time as low and patient discomfort as optimal as possible.

A review of image-enhanced endoscopy in the evaluation of colonic polyps

The practice of colonoscopy has changed considerably over the last decade. The growth of image-enhanced endoscopy have altered our concepts of how we perform colonoscopy. This article examines the evidence base behind these techniques and looks at where future research needs to be directed.

Endoscopic versus histological characterisation of polyps during screening colonoscopy

BACKGROUND

As screening colonoscopy becomes more widespread, the costs for histopathological assessment of resected polyps are rising correspondingly. Reference centres have published highly accurate results for endoscopic polyp classification. Therefore, it has been proposed that, for smaller polyps, the differential diagnosis that guides follow-up recommendations could be based on endoscopy alone.

OBJECTIVE

The aim was to prospectively assess whether the high accuracy for endoscopic polyp diagnosis as reported by reference centres can be reproduced in routine screening colonoscopy.

DESIGN

Ten experienced private practice endoscopists had initial training in pit patterns. Then they assessed all polyps detected during 1069 screening colonoscopies. Patients (46% men; mean age 63 years) were randomly assigned to colonoscopy with conventional or latest generation HDTV instruments. The main outcome measure was diagnostic accuracy of in vivo polyp assessment (adenomatous vs hyperplastic). Secondary outcome measures were differences between endoscopes and reliability of image-based follow-up recommendations; a blinded post hoc analysis of polyp photographs was also performed.

RESULTS

675 polyps were assessed (461 adenomatous, 214 hyperplastic). Accuracy, sensitivity and specificity of in vivo diagnoses were 76.6%, 78.1% and 73.4%; size of adenomas and endoscope withdrawal time significantly influenced accuracy. Image-based recommendations for post-polypectomy surveillance were correct in only 69.5% of cases. Post hoc analysis of polyp photographs did not improve accuracy.

CONCLUSIONS

In everyday practice, endoscopic classification of polyp type is not accurate enough to abandon histopathological assessment and use of latest generation colonoscopes does not improve this. Image-based surveillance recommendations after polypectomy would consequently not meet guideline requirements.

TRIALREGNO

NCT01297712.

Image-enhanced, chromo, and cap-assisted colonoscopy for improving adenoma/neoplasia detection rate: a systematic review and meta-analysis

OBJECTIVE

The effectiveness of narrow band imaging (NBI), chromoendoscopy (CE), and cap-assisted colonoscopy (CAC) on adenoma detection rate (ADR) has been investigated in previous meta-analyses; however, there have been no meta-analyses of autofluorescence imaging (AFI) or flexible spectral imaging color enhancement (FICE) or i-scan. The aim of this study was to determine whether AFI and FICE/i-scan was more effective than standard/high-definition white light endoscopy to improve ADR and to update previous meta-analyses of NBI, CE, and CAC.

DESIGN

A systematic review and meta-analysis was conducted. Four investigators selected appropriate randomized controlled trials (RCT) using the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guideline. All RCTs in which colonoscopy were performed with AFI, FICE, i-scan, NBI, CE, and CAC were included. The risk ratios (RRs) calculated from adenoma/neoplasia detection rate were used as the main outcome measurement.

RESULTS

A total of 42 studies were included in the analysis. Pooled estimates of RR (95%confidence interval [CI]) using AFI, FICE/i-scan, NBI, CE, and CAC were 1.04 (95% CI: 0.87-1.24) (I² = 0%) (fixed effects model [FEM]); 1.09 (95% CI: 0.97-1.23) (I² = 5%) (FEM); 1.03 (95% CI: 0.96-1.11) (I² = 0%) (FEM); 1.36 (95% CI: 1.23-1.51) (I² = 16%) (FEM); and 1.03 (95% CI: 0.93-1.14) (I² = 48%) (random effects model [REM]), respectively. The pooled estimate of RR (95%CI) using indigo carmine in non-ulcerative colitis (UC) patients and methylene blue in UC patients was 1.33 (95% CI: 1.20-1.48) (I² = 14%) (FEM) and 2.39 (95% CI: 1.18-4.84) (I² = 0%) (FEM), respectively.

CONCLUSION

In contrast to AFI, FICE/i-scan, NBI, and CAC, only CE improves ADR. CE with methylene blue, though not NBI, is effective for surveillance of neoplasia in chronic UC patients.

Differential diagnosis of colorectal polyps with respect to similar capabilities of white light colonoscopy and narrow-band imaging

PURPOSE

The responses of polyps to light essentially determine the diagnostic capability of an endoscopy system in differentiating adenomas from hyperplastic polyps. Compared with white light colonoscopy (WLC), narrow-band imaging (NBI) is expected to improve the diagnostic capability. The diagnostic capabilities of WLC and NBI are evaluated and compared based on the polyp responses.

METHODS

The following WLC and NBI images were retrospectively reviewed and categorized: 195 images and polyps (89 WLC, 106 NBI) with the best visual quality were categorized in the best image group (BG), and 484 images of 242 polyps (both WLC and NBI) were categorized in the paired image group (PG). For each reflection of light used for WLC or NBI, the polyp responses were objectively expressed as reflection features. The reflection features were then used to establish a classification model for identifying adenomas. The diagnostic capability of reflection feature or classification model was measured by the area under the receiver operating characteristic curve (AUC).

RESULTS

In both image groups, the diverse and heterogeneous features of the polyp responses enabled accurate identification of adenomas, regardless of the light source used for WLC and NBI. For differential diagnosis of adenomas and hyperplastic polyps, the WLC and NBI did not significantly differ in BG (AUC, 0.905 and 0.922, respectively; P = 0.690) or in PG (AUC, 0.782 and 0. 769, respectively; P = 0.755).

CONCLUSIONS

Using WLC and NBI as classification models is effective in differential diagnosis of colorectal polyps and exhibited similar capabilities.

Design and characterization of an optimized simultaneous color and near-infrared fluorescence rigid endoscopic imaging system

We report the design, characterization, and validation of an optimized simultaneous color and near-infrared (NIR) fluorescence rigid endoscopic imaging system for minimally invasive surgery. This system is optimized for illumination and collection of NIR wavelengths allowing the simultaneous acquisition of both color and NIR fluorescence at frame rates higher than 6.8 fps with high sensitivity. The system employs a custom 10-mm diameter rigid endoscope optimized for NIR transmission. A dual-channel light source compatible with the constraints of an endoscope was built and includes a plasma source for white light illumination and NIR laser diodes for fluorescence excitation. A prism-based 2-CCD camera was customized for simultaneous color and NIR detection with a highly efficient filtration scheme for fluorescence imaging of both 700- and 800-nm emission dyes. The performance characterization studies indicate that the endoscope can efficiently detect fluorescence signal from both indocyanine green and methylene blue in dimethyl sulfoxide at the concentrations of 100 to 185 nM depending on the background optical properties. Finally, we performed the validation of this imaging system in vivo during a minimally invasive procedure for thoracic sentinel lymph node mapping in a porcine model.

A randomized crossover open trial of the adenoma miss rate for narrow band imaging (NBI) versus flexible spectral imaging color enhancement (FICE)

PURPOSE

Narrow band imaging (NBI) and flexible spectral imaging color enhancement (FICE) allow improved contrasted evaluation of the mucosal surface. However, no study has compared the utility of these two modalities. Therefore, the aim of this study was to compare the adenoma miss rate (AMR) between NBI and FICE.

METHODS

A total of 55 patients (38 men, 17 women) were enrolled in this study. Patients were randomly assigned to the NBI-FICE group (NBI followed by FICE) or the FICE-NBI group (FICE followed by NBI). NBI and FICE total colonic observations were tandemly performed for each patient during the scope withdrawal with white light following cecal intubation. All detected polyps with the NBI or FICE observation were categorized into three groups according to the size and number of polyps missed.

RESULTS

Twenty-nine patients were assigned to the NBI-FICE group, and 26 patients were assigned to the FICE-NBI group. There was no significant difference in the overall AMR when comparing the image-enhanced endoscopy technologies (17.9 % for NBI, 26 % for FICE, p = 0.159). AMR was lower for NBI than for FICE for adenomas <5 mm in diameter (5.7 % for NBI, 12.6 % for FICE, p = 0.036). AMR was not significantly different when comparing NBI and FICE for lesions 5 to 10 mm (p = 0.967) or for lesions ≥10 mm (p = 0.269).

CONCLUSIONS

This study demonstrated that overall AMR was not different when comparing NBI and FICE.

Enhanced visibility of colonic neoplasms using formulaic ratio imaging of native fluorescence

BACKGROUND AND OBJECTIVES

Colonoscopy is the preferred method for colon cancer screening, but can miss polyps and flat neoplasms with low color contrast. The objective was to develop a new autofluorescence method that improves image contrast of colonic neoplasms.

STUDY DESIGN/MATERIALS AND METHODS

We selected the three strongest native fluorescence signals and developed a novel method where fluorescence images are processed in a ratiometric formula to represent the likely cellular and structural changes associated with neoplasia. Native fluorescence images of fresh surgical specimens of the colon containing normal mucosa, polypoid and flat adenomas as well as adenocarcinoma were recorded using a prototype multi-spectral imager. Sixteen patients, with a mean age of 62 years (range 28-81) undergoing elective resection for colonic neoplasms were enrolled. High contrast images were seen with fluorescence from tryptophan (Tryp), flavin adenine dinucleotide (FAD) and collagen.

RESULTS

When the image intensity of Tryp was divided pixel by pixel, by the intensities of FAD and collagen, the resulting formulaic ratio (FR) images were of exceptionally high contrast. The FR images of adenomas and adenocarcinomas had increased Weber contrast.

CONCLUSIONS

FR imaging is a novel imaging process that represents the likely metabolic and structural changes in colonic neoplasia that produces images with remarkably high contrast.

Ancillary imaging techniques and adenoma detection

Advancements in image technology have allowed recognition of mucosal architecture in more detail and may improve adenoma detection. This review provides a technical overview on individual imaging technologies and their effect on detection of adenomas. Only high-definition endoscopy has been shown to improve detection of small adenomas. None of the digital chromoendoscopy technologies improves adenoma detection. Limited studies on autoimmunfluorescence imaging in conjunction with high-definition endoscopy may improve detection of small adenomas.

Colon polypectomy: a review of routine and advanced techniques

The value of performing comprehensive screening colonoscopy with complete colon polypectomy is widely accepted. Colon cancer is a significant cause of worldwide mortality and prospective studies have proven that colonoscopic polypectomy reduces both the incidence and mortality related to this disease. Over the past few decades the array of instruments and techniques have greatly expanded to assist with the safe endoscopic removal of colon polyps. This article will review the published literature regarding efficacy and safety of standard polypectomy techniques such as snare polypectomy, electrocautery, and endoscopic mucosal resection along with newer techniques such as endoscopic submucosal dissection and combined laparoscopic techniques.

Real-time histology in colonoscopy

Gastrointestinal endoscopy had major technological improvements and novel technologies in recent years. High-definition endoscopy has permitted an increasingly detailed view of the mucosa during colonoscopy. Filter techniques that enhance analysis of vessel and surface structures. Autofluorescence imaging relies on functional imaging of tissue alterations. Endocytoscopy is an ultrahigh-contact microscopy procedure for cellular analysis of the epithelium. Endomicroscopy is an adaption of laser scanning microscopy for real-time intravital surface and subsurface microscopy during endoscopy. With these technologies, endoscopy has moved from prediction of histology based on morphologic patterns toward visualization of cellular and subcellular details, providing real-time histology.

Endoscopy and polyps-diagnostic and therapeutic advances in management

Despite multiple efforts aimed at early detection through screening, colon cancer remains the third leading cause of cancer-related deaths in the United States, with an estimated 51000 deaths during 2013 alone. The goal remains to identify and remove benign neoplastic polyps prior to becoming invasive cancers. Polypoid lesions of the colon vary widely from hyperplastic, hamartomatous and inflammatory to neoplastic adenomatous growths. Although these lesions are all benign, they are common, with up to one-quarter of patients over 60 years old will develop pre-malignant adenomatous polyps. Colonoscopy is the most effective screening tool to detect polyps and colon cancer, although several studies have demonstrated missed polyp rates from 6%-29%, largely due to variations in polyp size. This number can be as high as 40%, even with advanced (> 1 cm) adenomas. Other factors including sub-optimal bowel preparation, experience of the endoscopist, and patient anatomical variations all affect the detection rate. Additional challenges in decision-making exist when dealing with more advanced, and typically larger, polyps that have traditionally required formal resection. In this brief review, we will explore the recent advances in polyp detection and therapeutic options.

Practices and impact of primary outcome adjustment in randomized controlled trials: meta-epidemiologic study

OBJECTIVE

To assess adjustment practices for primary outcomes of randomized controlled trials and their impact on the results.

DESIGN

Meta-epidemiologic study.

DATA SOURCES

25 biomedical journals with the highest impact factor according to Journal Citation Reports 2009.

STUDY SELECTION

Randomized controlled trials published in print in 2009 that reported primary outcomes. The search yielded 684 eligible papers of randomized controlled trials, of which 200 were randomly selected.

DATA EXTRACTION

Two researchers independently extracted data on study population, intervention, primary outcome, and the adjustment plan for primary outcomes. They also recorded the magnitude and statistical significance of the intervention effect with and without adjustments, and estimated whether adjustment made a difference in the level of nominal significance. They also compared the analysis plan for model adjustment in the published trial versus the trial protocol with information on the protocol collected from registries, design papers, and communication with all corresponding authors.

RESULTS

54% of the trials used stratified randomization, 96% presented baseline characteristics in the compared arms, and 46% also evaluated differences in baseline factors with statistical testing. Half of the trials performed adjusted analyses for the main outcome, as the sole analysis (29%) or along with unadjusted analyses (21%). Adjustment for stratification variables and for baseline variables was performed in 39% (42/108) and 42% (84/199) of the trials, respectively. Among 40 comparisons with both adjusted and unadjusted analyses, 43% had statistically significant effects, 40% had non-significant effects, and 18% had significant effects with only one of the two analyses, but not with the other. Information on analysis plan regarding model adjustment was available in 6% (9/162) of trial registry entries, 78% (21/27) of design papers, and 74% (40/54) of protocols obtained from authors. The analysis plan disagreed between the published trial and the registry, protocol, or design paper in 47% (28/60) of the studies.

CONCLUSIONS

There is large diversity on whether and how analyses of primary outcomes are adjusted in randomized controlled trials and these choices can sometimes change the nominal significance of the results. Registered protocols should explicitly specify adjustments plans for main outcomes and analysis should follow these plans.

Interobserver variability and accuracy of high-definition endoscopic diagnosis for gastric intestinal metaplasia among experienced and inexperienced endoscopists

Accurate diagnosis of gastric intestinal metaplasia is important; however, conventional endoscopy is known to be an unreliable modality for diagnosing gastric intestinal metaplasia (IM). The aims of the study were to evaluate the interobserver variation in diagnosing IM by high-definition (HD) endoscopy and the diagnostic accuracy of this modality for IM among experienced and inexperienced endoscopists. Selected 50 cases, taken with HD endoscopy, were sent for a diagnostic inquiry of gastric IM through visual inspection to five experienced and five inexperienced endoscopists. The interobserver agreement between endoscopists was evaluated to verify the diagnostic reliability of HD endoscopy in diagnosing IM, and the diagnostic accuracy, sensitivity, and specificity were evaluated for validity of HD endoscopy in diagnosing IM. Interobserver agreement among the experienced endoscopists was "poor" (κ = 0.38) and it was also "poor" (κ = 0.33) among the inexperienced endoscopists. The diagnostic accuracy of the experienced endoscopists was superior to that of the inexperienced endoscopists (P = 0.003). Since diagnosis through visual inspection is unreliable in the diagnosis of IM, all suspicious areas for gastric IM should be considered to be biopsied. Furthermore, endoscopic experience and education are needed to raise the diagnostic accuracy of gastric IM.

Precancerous lesions in inflammatory bowel disease

Reduction of mortality from colorectal cancer is a prime goal in the clinical management of patients with extensive, longstanding ulcerative colitis and colonic Crohn's disease. The cornerstone of current cancer prevention efforts is endoscopic surveillance for colorectal dysplasia, or intraepithelial neoplasia, the direct histological precursor of cancer. A diagnosis of dysplasia provides a reliable indicator of heightened cancer risk and an end-point for colonoscopic surveillance allowing most patients to undergo prophylactic colectomy before the development of incurable cancer. This article reviews the classification, pathological criteria and clinical implications of colorectal dysplasia, current recommendations for the performance of surveillance colonoscopy, recent technical advances in colonoscopic imaging to enhance the detection of dysplasia, and a summary of the molecular genetic events implicated in its development.

Interobserver agreement among endoscopists on evaluation of polypoid colorectal lesions visualized with the Pentax i-Scan technique

BACKGROUND AND AIMS

Advances in colonoscopy, such as the Pentax i-Scan electronic technique, have the potential to improve the early detection of colorectal cancer. The aim of this multicentre study was to assess the interobserver agreement in the visualization of the surface and margins of colorectal polyps and in distinguishing neoplastic from non-neoplastic polyps.

PATIENTS AND METHODS

Eight expert endoscopists examined 400 mixed previously recorded images of polyps taken with different Pentax i-Scan settings in order to give an evaluation of the surface of the polyp and regular colonic mucosa, the pit-pattern and the nature of the lesion.

RESULTS

A total of 400 mixed images of polyps with a diameter >5mm and <10mm were stored for analysis. Overall, there was a Kf agreement of 0.370 (p<0.001) and 0.306 (p<0.001) regarding pit-pattern and margins, respectively. The Kf agreement for the difference between neoplastic and non-neoplastic lesions was of 0.446 (p<0.001).

CONCLUSIONS

We observed good interobserver agreement in the evaluation of neoplastic and non-neoplastic lesions and poor agreement in the evaluation of pit-pattern and margins. Adequate training is required in order to interpret images acquired with the i-Scan technique.

Using high frequency Raman spectra for colonic neoplasia detection

Raman systems have tremendous potential as adjunct devices for endoscopes to improve the identification of early colon cancers. However, the traditional low frequency (LF) measurement range has several obstacles that make it challenging to develop a routine clinical tool. An alternative is to use high frequency (HF) range. To test this idea Raman spectra were obtained in both the LF and HF ranges from the same colon lesions. Multivariate analyses predicted the pathology with high sensitivity and specificity for both the LF and HF data sets. This suggests that Raman systems that measure HF spectra, and are simpler to adopt into the clinic, could be used in vivo to improve the identification of neoplastic lesions.

Rationale for and clinical benefits of colonoscopy with narrow band imaging: pathological prediction and colorectal screening

INTRODUCTION

Narrow-band imaging (NBI), an emerging imaging technology, allows direct visualization of capillaries on the gastrointestinal mucosal surface. The combination of NBI and magnifying endoscopy can be used to identify morphological changes in these capillaries during the process of carcinogenesis.

FINDINGS AND CONCLUSIONS

Thus far, pathological predictions based on capillary pattern classifications have been reported to have good diagnostic accuracy. However, most of these studies have been single-center trials based on each institutional classification, and worldwide multicenter trials aimed at their standardization are needed to validate the clinical benefits of the various NBI classification systems.

Image-enhanced endoscopy for diagnosis of colorectal tumors in view of endoscopic treatment

Recently, image-enhanced endoscopy (IEE) has been used to diagnose gastrointestinal tumors. This method is a change from conventional white-light (WL) endoscopy without dyeing solution, requiring only the push of a button. In IEE, there are many advantages in diagnosis of neoplastic tumors, evaluation of invasion depth for cancerous lesions, and detection of neoplastic lesions. In narrow band imaging (NBI) systems (Olympus Medical Co., Tokyo, Japan), optical filters that allow narrow-band light to pass at wavelengths of 415 and 540 nm are used. Mucosal surface blood vessels are seen most clearly at 415 nm, which is the wavelength that corresponds to the hemoglobin absorption band, while vessels in the deep layer of the mucosa can be detected at 540 nm. Thus, NBI also can detect pit-like structures named surface pattern. The flexible spectral imaging color enhancement (FICE) system (Fujifilm Medical Co., Tokyo, Japan) is also an IEE but different to NBI. FICE depends on the use of spectral-estimation technology to reconstruct images at different wavelengths based on WL images. FICE can enhance vascular and surface patterns. The autofluorescence imaging (AFI) video endoscope system (Olympus Medical Co., Tokyo, Japan) is a new illumination method that uses the difference in intensity of autofluorescence between the normal area and neoplastic lesions. AFI light comprises a blue light for emitting and a green light for hemoglobin absorption. The aim of this review is to highlight the efficacy of IEE for diagnosis of colorectal tumors for endoscopic treatment.

Endoscopic detection of colorectal adenomas: standards and sophisticated methods

Colorectal cancer represents one of the leading malignancies worldwide. Early endoscopic detection and removal of its precursor lesions, adenomas, and serrated hyperplastic polyps results in a decrease of colon cancer-related death. However, miss rates in adenoma detection up to 26% underline the need for high compliance to basic measures and further improvement in methodology and technology. Basic parameters affecting adenoma detection rates include sufficient training and awareness of the endoscopist, use of high-definition endoscopes, careful examination behind folds, cleansing the colon wall, accurate distention of the colon, and adequate withdrawal time. Advanced imaging techniques, introduced to further improve adenoma detection, have yielded mixed results. These include wide-angle colonoscopes, cap-assisted colonoscopy, and retroscopic methods which may add new obstacles to colonoscopy. Moreover, chromoendoscopy either 'virtual' or by topically applied dyes has been suggested to enhance the detection of colonic neoplasia. Yet, studies on patients with average cancer risk have failed to reproduce promising initial results. Similarly, although autofluorescence has not enhanced the diagnostic yield in screening a population at average risk, it may be useful in patients at increased cancer risk. Recently, technical feasibility of molecular imaging employing 'biomarkers' has been demonstrated, but needs further evaluation. The newest developments, employing light-scattering spectroscopy, suggest the existence of a 'field effect' of colonic carcinogenesis and may enable detection of the earliest neoplastic events and distant adenomas even when applied to normal-appearing mucosa. Upon confirmation, these technologies may result in a substantial change in patient management and risk stratification.

Endoscopic techniques for improving colorectal adenoma detection: Recent progress

Colorectal cancer (CRC) is one of the most common malignant neoplasms worldwide and develops mostly from precancerous lesions such as colorectal adenomas. Therefore, early detection and resection of colorectal adenomas is key to preventing CRC. At present, colonoscopy is acknowledged as the gold standard for the diagnosis and treatment of colorectal lesions; however, conventional colonoscopy is still associated with a certain rate of missed lesions. It is reported that the missed detection rate is 6% when adenomas are more than 1 cm, 13% for adenomas 6-9 mm, and 27% for adenomas less than 5 mm. The missed detection rate for right colonic adenomas is higher than that for left colonic adenomas. The missed diagnosis of colorectal adenomas or malignant tumors invariably increases surgical rate and mortality. Currently, great efforts have been made to improve the detection rate of colorectal adenomas. This paper will briefly review recent advances in endoscopic techniques for improving the detection rate of colorectal adenomas.

High-definition colonoscopy with i-Scan: Better diagnosis for small polyps and flat adenomas

AIM: To investigate if high-definition (HD) colonoscope with i-Scan gave a higher detection rate of mucosal lesions vs standard white-light instruments.

METHODS: Data were collected from the computerized database of the endoscopy unit of our tertiary referral center. We retrospectively analyzed 1101 consecutive colonoscopies that were performed over 1 year with standard white-light (n = 849) or HD+ with i-Scan (n = 252) instruments by four endoscopists, in an outpatient setting. Colonoscopy records included patients’ main details and family history for colorectal cancer, indication for colonoscopy (screening, diagnostic or surveillance), type of instrument used (standard white-light or HD+ plus i-Scan), name of endoscopist and bowel preparation. Records for each procedure included whether the cecum was reached or not and the reason for failure, complications during or immediately after the procedure, and number, size, location and characteristics of the lesions. Polyps or protruding lesions were defined as sessile or pedunculated, and nonprotruding lesions were defined according to Paris classification. For each lesion, histological diagnosis was recorded.

RESULTS: Eight hundred and forty-nine colonoscopies were carried with the standard white-light video colonoscope and 252 with the HD+ plus i-Scan video colonoscope. The four endoscopists did 264, 300, 276 and 261 procedures, respectively; 21.6%, 24.0%, 21.7% and 24.1% of them with the HD+ plus i-Scan technique. There were no significant differences between the four endoscopists in either the number of procedures done or the proportions of each imaging technique used. Both techniques detected one or more mucosal lesions in 522/1101 procedures (47.4%). The overall number of lesions recognized was 1266; 645 in the right colon and 621 in the left. A significantly higher number of colonoscopies recognized lesions in the HD+ plus i-Scan mode (171/252 = 67.9%) than with the standard white-light technique (408/849 = 48.1%) (P < 0.0001). HD+ with i-Scan colonoscopies identified more lesions than standard white-light imaging (459/252 and 807/849, P < 0.0001), in the right or left colon (mean ± SD, 1.62 ± 1.36 vs 1.33 ± 0.73, P < 0.003 and 1.55 ± 0.98 vs 1.17 ± 0.93, P = 0.033), more lesions < 10 mm (P < 0.0001) or nonprotruding (P < 0.022), and flat polyps (P = 0.04). The cumulative mean number of lesions per procedure detected by the four endoscopists was significantly higher with HD+ with i-Scan than with standard white-light imaging (1.82 ± 2.89 vs 0.95 ± 1.35, P < 0.0001).

CONCLUSION: HD imaging with i-Scan during the withdrawal phase of colonoscopy significantly increased the detection of colonic mucosal lesions, particularly small and nonprotruding polyps.

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.

Role of narrow band imaging in endoscopic submucosal dissection

Narrow band imaging (NBI) is a new image enhancement system employing optic digital methods to enhance images of blood vessels on mucosal surfaces, allowing improved visualization of mucosal surface structures. Studies have progressed over the last several years, and the clinical usefulness has been demonstrated. NBI has become frequently applied for preoperative diagnosis before endoscopic submucosal dissection (ESD) of digestive tract cancers, as well as for assessment of the range of ESD for en-bloc resection of large lesions. Consensus has been reached with regard to the usefulness of NBI for detecting micro-lesions of esophageal squamous cell carcinoma indicated for ESD, for the diagnosis of the range and depth. NBI has also been attracting attention for diagnosing gastric cancer based on the observation of micro blood vessels on the mucosal surface and mucosal surface microstructures. The usefulness of NBI has been reported in relation to various aspects of colon cancer, including diagnoses of the presence, quality, range, and depth of lesions. However, as NBI has not surpassed diagnostic methods based on magnifying observation combined with the established and widely employed dye method, its role in ESD is limited at present. Although NBI is very useful for the diagnosis of digestive tract cancers, comprehensive endoscopic diagnosis employing the combination of conventional endoscopy including dye spraying, EUS, and NBI may be important and essential for ESD.

Water-aided colonoscopy: a systematic review

BACKGROUND

Water-aided methods for colonoscopy are distinguished by the timing of removal of infused water, predominantly during withdrawal (water immersion) or during insertion (water exchange).

OBJECTIVE

To discuss the impact of these approaches on colonoscopy pain and adenoma detection rate (ADR).

DESIGN

Systematic review.

SETTING

Randomized, controlled trial (RCT) that compared water-aided methods and air insufflation during colonoscope insertion.

PATIENTS

Patients undergoing colonoscopy.

INTERVENTION

Medline, PubMed, and Google searches (January 2008-December 2011) and personal communications of manuscripts in press were considered to identify appropriate RCTs.

MAIN OUTCOME MEASUREMENTS

Pain during colonoscopy and ADR. RCTs were grouped according to whether water immersion or water exchange was used. Reported pain scores and ADR were tabulated based on group assignment.

RESULTS

Pain during colonoscopy is significantly reduced by both water immersion and water exchange compared with traditional air insufflation. The reduction in pain scores was qualitatively greater with water exchange as compared with water immersion. A mixed pattern of increases and decreases in ADR was observed with water immersion. A higher ADR, especially proximal to the splenic flexure, was obtained when water exchange was implemented.

LIMITATIONS

Differences in the reports limit application of meta-analysis. The inability to blind the colonoscopists exposed the observations to uncertain bias.

CONCLUSION

Compared with air insufflation, both water immersion and water exchange significantly reduce colonoscopy pain. Water exchange may be superior to water immersion in minimizing colonoscopy discomfort and in increasing ADR. A head-to-head comparison of these 3 approaches is required.

Indigocarmine added to the water exchange method enhances adenoma detection - a RCT

PURPOSE

Chromoendoscopy with dye spray and the water method both increase adenoma detection.

HYPOTHESIS

Adding indigocarmine to the water method will enhance further the effectiveness of the latter in adenoma detection.

METHODS

Screening colonoscopy was performed with the water method (control) or with 0.008% indigocarmine added (study) by two endoscopists. Randomization was based on computer-generated codes contained in blocks of pre-arranged opaque sealed envelopes. High resolution colonoscopes were used. Upon insertion into the rectum, air was suctioned. With the air pump turned off, water was infused using a blunt needle adaptor connected to the scope channel and a foot pump to facilitate scope insertion until the cecum was reached. Residual stool causing cloudiness was suctioned followed by infusion of clear or colored water (water exchange) to facilitate scope passage with minimal distention of the colonic lumen. Upon seeing the appendix opening under water, water was suctioned and air was insufflated to facilitate inspection on scope withdrawal.

STATISTICS

Sample size calculation revealed 168 patients (84/group) needed to be randomized. Study was IRB-approved and registered (NCT01383265).

RESULTS

There were no significant differences in mean age, gender distribution, BMI, and family history of colon cancer. Cecal intubation success rate was 100% in both groups. The overall adenoma detection rate was 44% (water only) versus 62% (water with indigocarmine), respectively (p=0.03). One cancer was detected in each group.

CONCLUSION

In a RCT, indigocarmine at 0.008% concentration, added to the water method, significantly enhanced further the effectiveness of the latter in detecting adenomas.

Meta-analysis for evaluating the accuracy of endoscopy with narrow band imaging in detecting colorectal adenomas

BACKGROUND AND AIM

The aim of this study was to determine whether the use of the narrow band imaging (NBI) system could enhance the accuracy of adenoma detection during an endoscopic examination of the colon and rectum.

METHODS

MEDLINE, EMBASE, and the Cochrane Library databases were searched along with a hand search of abstracts from relevant conferences up to June 2011. The rates of adenoma and flat adenoma detection, and withdrawal time were analyzed using Review Manager 4.2.

RESULTS

A total of 3049 subjects in eight trials were included. Meta-analysis revealed that there was no statistically significant difference in the rates of adenoma detection between the NBI group and the white light colonoscopy group (pooled relative risk [RR]: 1.09, 95% confidence interval [CI]: 1.00-1.19, P = 0.05). However, after exclusion of high-definition television modalities, the rate of adenoma detection by NBI was significantly higher than that by white light, particularly for patients with one adenoma (pooled RR 1.36, 95%CI 1.07-1.71, P = 0.02). Endoscopy with the NBI system significantly increased the rate of flat adenoma detection (pooled RR 1.96, 95%CI 1.09-3.52, P = 0.02). However, endoscopy with NBI had longer withdrawal time than that with white light (pooled weighted mean difference: 0.90, 95%CI: 0.38-1.42, P = 0.0006).

CONCLUSIONS

Endoscopy with NBI seems to improve the detection of flat adenomas, particularly with high-definition technology, but prolongs the withdrawal time. These results indicate that endoscopy routinely using the NBI system for the surveillance of adenomas may be recommended after the technique is further modified.

Prospective, randomized, back-to-back trial evaluating the usefulness of i-SCAN in screening colonoscopy

BACKGROUND

The newly developed i-SCAN application can theoretically maximize the effectiveness of colonoscopy. However, the practical usefulness of the i-SCAN application during screening colonoscopy has not been assessed.

OBJECTIVE

To assess the efficacy of the i-SCAN application during screening colonoscopy.

DESIGN

A prospective, randomized trial that used a modified, back-to-back colonoscopy.

SETTING

Academic hospital.

PATIENTS

This study involved 389 asymptomatic, consecutive, average-risk patients who underwent screening colonoscopy.

INTERVENTION

The patients were randomized to the first withdrawal with either conventional high-definition white light (HDWL group; n = 119), i-SCAN contrast/surface enhancement (CE/SE) mode (i-SCAN1 group; n = 115), or i-SCAN CE/SE/tone enhancement-colorectal mode (i-SCAN2 group; n = 118). All patients underwent a second examination with HDWL as the criterion standard.

MAIN OUTCOME MEASUREMENTS

The primary outcome measurement was the adenoma detection rate and adenoma miss rate. The secondary outcome measurement was the accuracy of the histologic prediction of neoplastic and nonneoplastic polyps.

RESULTS

The adenoma detection rates during the first withdrawal of HDWL, i-SCAN1, and i-SCAN2 were 31.9%, 36.5%, and 33.1%, respectively (P = .742), and the adenoma miss rates of each group were 22.9%, 19.3%, and 15.9%, respectively (P = .513). Based on the multivariate analysis, the application of i-SCAN was not associated with an improvement in adenoma detection and the prevention of missed polyps. However, the prediction of neoplastic and nonneoplastic colorectal lesions was more precise in the i-SCAN2 group compared with the HDWL group (accuracy 79.3% vs 75.5%, P = .029; sensitivity 86.5% vs 72.6%, P = .020; and specificity 91.4% vs 80.6%, P = .040).

LIMITATIONS

Single-center trial.

CONCLUSION

i-SCAN during the screening colonoscopy may fail to improve adenoma detection and the prevention of missed polyps, but i-SCAN appears to be effective for real-time histologic prediction of polyps compared with conventional HDWL colonoscopy. (

CLINICAL TRIAL REGISTRATION NUMBER

NCT01417611.).

Progress and challenges in colorectal cancer screening

Although faecal and endoscopic tests appear to be effective in reducing colorectal cancer incidence and mortality, further technological and organizational advances are expected to improve the performance and acceptability of these tests. Several attempts to improve endoscopic technology have been made in order to improve the detection rate of neoplasia, especially in the proximal colon. Based on the latest evidence on the long-term efficacy of screening tests, new strategies including endoscopic and faecal modalities have also been proposed in order to improve participation and the diagnostic yield of programmatic screening. Overall, several factors in terms of both efficacy and costs of screening strategies, including the high cost of biological therapy for advanced colorectal cancer, are likely to affect the cost-effectiveness of CRC screening in the future.

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

BACKGROUND

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.

OBJECTIVE

Our aim was to determine whether use of NBI enhances the detection of adenomas.

DESIGN

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."

PATIENTS

There was a total of 2936 patients in the NBI studies.

INTERVENTIONS

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.

MAIN OUTCOME MEASUREMENTS

Adenoma and polyp detection rates and the number of polyps and adenomas detected per person.

RESULTS

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).

LIMITATION

Variability in NBI studies can reduce the accuracy of this analysis.

CONCLUSIONS

NBI did not increase adenoma or polyp detection rates.

Trimodal endoscopic imaging for the detection and differentiation of colorectal adenomas: a prospective single-centre clinical evaluation

PURPOSE

The purpose of this study is to evaluate an endoscopic trimodal imaging (ETMI) system (high resolution, autofluorescence, and NBI) in the detection and differentiation of colorectal adenomas.

METHODS

A prospective randomised trial of tandem colonoscopies was carried out using the Olympus XCF-FH260AZI system. Each colonic segment was examined twice for lesions, once with HRE and once with AFI, in random order per patient. All detected lesions were assessed with NBI for pit pattern and with AFI for colour. All lesions were removed and sent for histology. Any lesion identified on the second examination was considered as missed by the first examination. Outcome measures are adenoma miss rates of AFI and HRE, and diagnostic accuracy of NBI and AFI for differentiating neoplastic from non-neoplastic lesions.

RESULTS

Ninety-four patients underwent colonoscopy with ETMI (47 in each group). Among 47 patients examined with AFI first, 31 adenomas in 15 patients were detected initially [detection rate 0.66 (0.52-0.75)]. Subsequent HRE inspection identified six additional adenomas. Among 47 patients examined with HRE first, 29 adenomas in 14 patients were detected initially [detection rate 0.62 (0.53-0.79)]. Successive AFI yielded seven additional adenomas. Adenoma miss rates of AFI and HRE were 14% and 16.2%, respectively (p = 0.29). Accuracy of AFI alone for differentiation was lower than NBI (63% vs. 80%, p < 0.001). Combined use of AFI and NBI achieved improved accuracy for differentiation (84%), showing a trend for superiority compared with NBI alone (p = 0.064).

CONCLUSIONS

AFI did not significantly reduce the adenoma miss rate compared with HRE. AFI alone had a disappointing accuracy for adenoma differentiation, which could be improved by combination of AFI and NBI.

Latest generation, wide-angle, high-definition colonoscopes increase adenoma detection rate

BACKGROUND & AIMS

Improvements to endoscopy imaging technologies might improve detection rates of colorectal cancer and patient outcomes. We compared the accuracy of the latest generation of endoscopes with older generation models in detection of colorectal adenomas.

METHODS

We compared data from 2 prospective screening colonoscopy studies (the Berlin Colonoscopy Project 6); each study lasted approximately 6 months and included the same 6 colonoscopists, who worked in private practice. Participants in group 1 (n = 1256) were all examined by using the latest generation of wide-angle, high-definition colonoscopes that were manufactured by the same company. Individuals in group 2 (n = 1400) were examined by endoscopists who used routine equipment (a mixture of endoscopes from different companies; none of those used to examine group 1). The adenoma detection rate was calculated on the basis of the number of all adenomas/number of all patients.

RESULTS

There were no differences in patient parameters or withdrawal time between groups (8.0 vs 8.2 minutes). The adenoma detection rate was significantly higher in group 1 (0.33) than in group 2 (0.27; P = .01); a greater number of patients with least 1 adenoma were identified in group 1 (22.1%) than in group 2 (18.2%; P = .01). A higher percentage of high-grade dysplastic adenomas were detected in group 1 (1.19%) than in group 2 (0.57%), but this difference was not statistically significant (P = .06).

CONCLUSIONS

The latest generation of wide-angle, high-definition colonoscopes improves rates of adenoma detection by 22%, compared with mixed, older technology endoscopes used in routine private practice. These findings might affect definitions of quality control parameters for colonoscopy screening for colorectal cancer.

Narrow band imaging versus conventional white light colonoscopy for the detection of colorectal polyps

BACKGROUND

It has been suggested that narrow band imaging colonoscopy (NBI) might be better for detection of colorectal polyps than white light colonoscopy (WLC).

OBJECTIVES

To compare standard or high definition white light colonoscopy with narrow band imaging colonoscopy for detection of colorectal polyps.

SEARCH METHODS

We searched The Cochrane Library, MEDLINE, and EMBASE to August 2011. We scanned bibliographies of relevant publications and wrote to experts for additional trials.

SELECTION CRITERIA

Two authors (NA and GB) independently applied the inclusion criteria and extracted the data to all potential studies without blinding.

DATA COLLECTION AND ANALYSIS

Authors extracted data independently. Trials with adequate randomisation, allocation concealment, and complete outcome data reporting, as well as without selective outcome reporting or other bias were classified as having a lowest risk of bias. Random-effects and fixed-effect meta-analyses were conducted.

MAIN RESULTS

We identified 11 randomised trials comparing WLC with NBI for detection of colorectal polyps. In total eight randomised trials with 3673 participants provided data for our analyses. There was no statistically significant difference between WLC (standard definition and high definition pooled) and NBI for the detection of patients with colorectal polyps (6 trials, n = 2832, RR 0.97, 95% CI 0.91 to 1.04), patients with colorectal adenomas (8 trials, n = 3673, RR 0.94, 95% CI 0.87 to 1.02), or patients with colorectal hyperplastic polyps (2 trials, n = 645, RR 0.87, 95% CI 0.76 to 1.00). Number of patients with at least one colorectal adenoma was not significantly different between WLC and NBI group irrespective of adenoma size (< 5 mm:RR 0.95, 95% CI 0.84 to 1.08, I(2) = 56%; 6 to 9 mm: RR 1.06, 95% CI 0.81 to 1.39, I(2) = 0%; ≥ 10 mm: RR 1.06, 95% CI 0.77 to 1.45, I(2) = 0%). Number of patients with at least one colorectal polyp, or colorectal adenoma was significantly lower in the standard definition WLC group compared to NBI group in fixed-effect meta-analysis (RR 0.87, 95% CI 0.78 to 0.97, I(2) = 78%; RR 0.87, 95% CI 0.77 to 0.99, I(2) = 0%, respectively), but not significantly different in random-effects meta-analysis (RR 0.86, 95% CI 0.68 to 1.10, I(2) = 78%). There was no statistically significant difference between high definition WLC and NBI in the number of patiens with at least one colorectal polyp or colorectal adenoma (RR 1.10, 95% CI 0.95 to 1.28; RR 0.87, 95% CI 0.77 to 0.99, I(2) = 0%, respectively).

AUTHORS' CONCLUSIONS

We could not find convincing evidence that NBI is significantly better than high definition WLC for the detection of patients with colorectal polyps, or colorectal adenomas. We found evidence that NBI might be better than standard definition WLC and equal to high definition WLC for detection the patients with colorectal polyps, or colorectal adenomas.

Tryptophan autofluorescence imaging of neoplasms of the human colon

Detection of flat neoplasia is a major challenge in colorectal cancer screening, as missed lesions can lead to the development of an unexpected 'incident' cancer prior to the subsequent endoscopy. The use of a tryptophan-related autofluorescence has been reported to be increased in murine intestinal dysplasia. The emission spectra of cells isolated from human adenocarcinoma and normal mucosa of the colon were studied and showed markedly greater emission intensity from cancerous cells compared to cells obtained from the surrounding normal mucosa. A proto-type multispectral imaging system optimized for ultraviolet macroscopic imaging of tissue was used to obtain autofluorescence images of surgical specimens of colonic neoplasms and normal mucosa after resection. Fluorescence images did not display the expected greater emission from the tumor as compared to the normal mucosa, most probably due to increased optical absorption and scattering in the tumors. Increased fluorescence intensity in neoplasms was observed however, once fluorescence images were corrected using reflectance images. Tryptophan fluorescence alone may be useful in differentiating normal and cancerous cells, while in tissues its autofluorescence image divided by green reflectance may be useful in displaying neoplasms.

Application of autofluorescence endoscopy for colorectal cancer screening: rationale and an update

As the result of basic researches, several intravital fluorophores have been determined so far in human colorectal tissue. Autofluorescence endoscopy (AFE) can detect slight alterations in their distribution and concentration during the colorectal carcinogenesis process and, thus facilitate noninvasive screening colonoscopies without the need for fluorescent substances or staining reagents to be administered. While detecting faint autofluorescence intensity by conventional fiberoptic endoscopy remains challenging, the latest AFE system with high-resolution videoendoscope capabilities enables such detection by using a false-color display algorithm. To this end, the diagnostic benefits of AFE have been reported in several multicenter randomized controlled studies of colorectal cancer (CRC) screening and differential diagnosis. CRC screening using the latest AFE technology could, therefore, lead to future reductions in CRC mortality.

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.