Endoscopic versus histological characterisation of polyps during screening colonoscopy

Second-generation distal attachment cuff for adenoma detection in screening colonoscopy: a randomized multicenter study

BACKGROUND AND AIMS

Randomized studies have demonstrated that a distal attachment cap with rubber side arms, the Endocuff Vision (ECV; Olympus America, Center Valley, Pa, USA), increased colonoscopic adenoma detection rate (ADR) in various mixed patient collectives. This is the first study to evaluate its use in a primary colonoscopic screening program.

METHODS

Patients over age 55 years undergoing screening colonoscopy in 9 German private offices in Berlin and Hamburg were randomized to either the study group using ECV or the control group using high-definition colonoscopies (standard of care). The main outcome parameter was ADR, whereas secondary outcomes were detection rates of all adenomas per colonoscopy (APCs), of adenoma subgroups, and of hyperplastic polyps.

RESULTS

Of 1416 patients (mean age, 61.1 years; 51.8% women), with a median of 41 examinations per examiner (n = 23; interquartile range, 12-81), 700 were examined with ECV and 716 without. Adjusting for the effects of the colonoscopies, ADR was 39.5% (95% confidence interval [CI], 32.6%-46.3%) in the ECV group versus 32.2% (95% CI, 25.9%-38.6%) in the control group, which resulted in an increase of 7.2% (95% CI, 2.3%-12.2%; P = .004). The increase in ADR was mainly because of small polyps, with adjusted ADRs for adenomas <10 mm of 33.3% (95% CI, 26.5%-40.2%) for study patients versus 24.0% (95% CI, 18.2%-29.8%) for control patients (P < .001). APC was also significantly increased (.57 ECV vs .51 control subjects, P = .045).

CONCLUSIONS

A distal attachment cap with side arms significantly increased the ADR in patients undergoing primary colonoscopic screening. Because of the correlation of ADR and interval cancer, its use should be encouraged, especially in this setting. (Clinical trial registration number: NCT03442738.).

Artificial intelligence-based measurement outperforms current methods for colorectal polyp size measurement

OBJECTIVES

An accurate polyp size estimation during colonoscopy is crucial to determine the surveillance interval and predict the risk of malignant progression. However, there is a high degree of subjectivity in estimating polyp size among endoscopists in clinical practice. We aimed to assess the efficacy of a novel method that uses artificial intelligence (AI) to measure the size of colon polyps and compare it with current approaches.

METHODS

Using the W-Net model for vessel segmentation and based on retinal image datasets (DRIVE, STARE, CHASE-DB, and HRF) and colonoscopy images, we developed the bifurcation-to-bifurcation (BtoB) distance measuring method and applied it to endoscopic images. Measurements were compared with those obtained by eight endoscopists (four expert and four trainees). Diagnostic ability and reliability were evaluated using Lin's concordance correlation coefficients (CCCs) and Bland-Altman analyses.

RESULTS

For both experts and trainees, visually estimated sizes of the same polyp were significantly inconsistent depending on the camera view used (P < 0.001). Bland-Altman analyses showed that there was a trend toward underestimation of the sizes of the polyps in both groups, especially for polyps larger than 10 mm. The new technique was highly accurate and reliable in measuring the size of colon polyp (CCC, 0.961; confidence interval 0.926-0.979), clearly outperforming the visual estimation and open biopsy forceps methods.

CONCLUSION

The new AI measurement method improved the accuracy and reliability of polyp size measurements in colonoscopy images. Incorporating AI might be particularly important to improve the efficiency of trainees at estimating polyp size during colonoscopy.

Non-optical polyp-based resect and discard strategy: A prospective clinical study

BACKGROUND

Post-polypectomy surveillance intervals are currently determined based on pathology results.

AIM

To evaluate a polyp-based resect and discard model that assigns surveillance intervals based solely on polyp number and size.

METHODS

Patients undergoing elective colonoscopies at the Montreal University Medical Center were enrolled prospectively. The polyp-based strategy was used to assign the next surveillance interval using polyp size and number. Surveillance intervals were also assigned using optical diagnosis for small polyps (< 10 mm). The primary outcome was surveillance interval agreement between the polyp-based model, optical diagnosis, and the pathology-based reference standard using the 2020 United States Multi-Society Task Force guidelines. Secondary outcomes included the proportion of reduction in required histopathology evaluations and proportion of immediate post-colonoscopy recommendations provided to patients.

RESULTS

Of 944 patients (mean age 62.6 years, 49.3% male, 933 polyps) were enrolled. The surveillance interval agreement for the polyp-based strategy was 98.0% [95% confidence interval (CI): 0.97-0.99] compared with pathology-based assignment. Optical diagnosis-based intervals achieved 95.8% (95%CI: 0.94-0.97) agreement with pathology. When using the polyp-based strategy and optical diagnosis, the need for pathology assessment was reduced by 87.8% and 70.6%, respectively. The polyp-based strategy provided 93.7% of patients with immediate surveillance interval recommendations vs 76.1% for optical diagnosis.

CONCLUSION

The polyp-based strategy achieved almost perfect surveillance interval agreement compared with pathology-based assignments, significantly reduced the number of required pathology evaluations, and provided most patients with immediate surveillance interval recommendations.

The location-based resect and discard strategy for diminutive colorectal polyps: a prospective clinical study

BACKGROUND

Clinical implementation of the resect-and-discard strategy has been difficult because optical diagnosis is highly operator dependent. This prospective study aimed to evaluate a resect-and-discard strategy that is not operator dependent.

METHODS

The study evaluated a resect-and-discard strategy that uses the anatomical polyp location to classify colonic polyps into non-neoplastic or low risk neoplastic. All rectosigmoid diminutive polyps were considered hyperplastic and all polyps located proximally to the sigmoid colon were considered neoplastic. Surveillance interval assignments based on these a priori assumptions were compared with those based on actual pathology results and on optical diagnosis. The primary outcome was ≥ 90 % agreement with pathology in surveillance interval assignment.

RESULTS

1117 patients undergoing complete colonoscopy were included and 482 (43.1 %) had at least one diminutive polyp. Surveillance interval agreement between the location-based strategy and pathological findings using the 2020 US Multi-Society Task Force guideline was 97.0 % (95 % confidence interval [CI] 0.96-0.98), surpassing the ≥ 90 % benchmark. Optical diagnoses using the NICE and Sano classifications reached 89.1 % and 90.01 % agreement, respectively (P < 0.001), and were inferior to the location-based strategy. The location-based resect-and-discard strategy allowed a 69.7 % (95 %CI 0.67-0.72) reduction in pathology examinations compared with 55.3 % (95 %CI 0.52-0.58; NICE and Sano) and 41.9 % (95 %CI 0.39-0.45; WASP) with optical diagnosis.

CONCLUSION

The location-based resect-and-discard strategy achieved very high surveillance interval agreement with pathology-based surveillance interval assignment, surpassing the ≥ 90 % benchmark and outperforming optical diagnosis in surveillance interval agreement and the number of pathology examinations avoided.

Activatable molecular probes for fluorescence-guided surgery, endoscopy and tissue biopsy

The real-time, dynamic optical visualization of lesions and margins ensures not only complete resection of the malignant tissues but also better preservation of the vital organs/tissues during surgical procedures. Most imaging probes with an "always-on" signal encounter high background noise due to their non-specific accumulation in normal tissues. By contrast, activatable molecular probes only "turn on" their signals upon reaction with the targeted biomolecules that are overexpressed in malignant cells, offering high target-to-background ratios with high specificity and sensitivity. This review summarizes the recent progress of activatable molecular probes in surgical imaging and diagnosis. The design principle and mechanism of activatable molecular probes are discussed, followed by specific emphasis on applications ranging from fluorescence-guided surgery to endoscopy and tissue biopsy. Finally, potential challenges and perspectives in the field of activatable molecular probe-enabled surgical imaging are discussed.

Mucosal Biofilms Are an Endoscopic Feature of Irritable Bowel Syndrome and Ulcerative Colitis

BACKGROUND & AIMS

Irritable bowel syndrome (IBS) and inflammatory bowel diseases result in a substantial reduction in quality of life and a considerable socioeconomic impact. In IBS, diagnosis and treatment options are limited, but evidence for involvement of the gut microbiome in disease pathophysiology is emerging. Here we analyzed the prevalence of endoscopically visible mucosal biofilms in gastrointestinal disease and associated changes in microbiome composition and metabolism.

METHODS

The presence of mucosal biofilms was assessed in 1426 patients at 2 European university-based endoscopy centers. One-hundred and seventeen patients were selected for in-depth molecular and microscopic analysis using 16S ribosomal RNA gene amplicon-sequencing of colonic biopsies and fecal samples, confocal microscopy with deep learning-based image analysis, scanning electron microscopy, metabolomics, and in vitro biofilm formation assays.

RESULTS

Biofilms were present in 57% of patients with IBS and 34% of patients with ulcerative colitis compared with 6% of controls (P < .001). These yellow-green adherent layers of the ileum and right-sided colon were microscopically confirmed to be dense bacterial biofilms. 16S-sequencing links the presence of biofilms to a dysbiotic gut microbiome, including overgrowth of Escherichia coli and Ruminococcus gnavus. R. gnavus isolates cultivated from patient biofilms also formed biofilms in vitro. Metabolomic analysis found an accumulation of bile acids within biofilms that correlated with fecal bile acid excretion, linking this phenotype with a mechanism of diarrhea.

CONCLUSIONS

The presence of mucosal biofilms is an endoscopic feature in a subgroup of IBS and ulcerative colitis with disrupted bile acid metabolism and bacterial dysbiosis. They provide novel insight into the pathophysiology of IBS and ulcerative colitis, illustrating that biofilm can be seen as a tipping point in the development of dysbiosis and disease.

Optical diagnosis of colorectal polyps: a randomized controlled trial comparing endoscopic image-enhancing modalities

BACKGROUND AND AIMS

Optical polyp diagnosis using image-enhanced endoscopy (IEE) allows for real-time histology prediction of colorectal polyps. The aim of this study was to evaluate a recently introduced IEE modality (Optivista [OV]; Pentax Medical, Tokyo, Japan) in a randomized controlled trial.

METHODS

In a prospective cohort of subjects (ages 45-80 years) undergoing elective screening, surveillance, or diagnostic colonoscopy, all colorectal polyps between 1 and 5 mm underwent IEE assessment. Study subjects were randomized before their colonoscopy procedure to undergo optical polyp diagnosis using either OV IEE or iScan (IS) IEE. A validated IEE scale (NBI International Colorectal Endoscopic classification) was used for optical polyp diagnosis. The primary outcome was the agreement of surveillance intervals determined when using OV IEE compared with IS IEE in reference with pathology-based surveillance intervals. Secondary outcomes were the percentage of surveillance intervals that could be given on the same day as the procedure, percentage of pathology tests avoided, diagnostic performance, and negative predictive value (NPV) of optical diagnosis for rectosigmoid adenomas.

RESULTS

Four hundred ten patients were enrolled in the trial. The polyp detection rate was 58.6%, and the adenoma detection rate was 38.8%. The proportion of correct surveillance interval assignment when using OV or IS IEE was 96.5% versus 96.0% (P = .75). A total of 65.1% of patients could be given same-day surveillance intervals when using OV IEE versus 73.1% for IS IEE (P = .07). The NPV for rectosigmoid adenomas (including sessile serrated adenomas) was 97.5% when using OV IEE and 88.2% when using IS IEE. Using high-confidence optical diagnosis instead of pathology would have resulted in a 44.3% elimination of required pathology examinations for OV IEE versus 52.8% for IS IEE (P = .34).

CONCLUSIONS

Optical diagnosis using OV and IS IEE both surpassed the 90% benchmark of surveillance interval assignment, and no significant difference with regard to correct surveillance interval assignment was found. OV IEE surpassed the ≥90% NPV for rectosigmoid adenomas, whereas IS IEE did not. (Clinical trial registration number: NCT03515343.).

Comparison of diagnostic performance between convolutional neural networks and human endoscopists for diagnosis of colorectal polyp: A systematic review and meta-analysis

Prospective randomized trials and observational studies have revealed that early detection, classification, and removal of neoplastic colorectal polyp (CP) significantly improve the prevention of colorectal cancer (CRC). The current effectiveness of the diagnostic performance of colonoscopy remains unsatisfactory with unstable accuracy. The convolutional neural networks (CNN) system based on artificial intelligence (AI) technology has demonstrated its potential to help endoscopists in increasing diagnostic accuracy. Nonetheless, several limitations of the CNN system and controversies exist on whether it provides a better diagnostic performance compared to human endoscopists. Therefore, this study sought to address this issue. Online databases (PubMed, Web of Science, Cochrane Library, and EMBASE) were used to search for studies conducted up to April 2020. Besides, the quality assessment of diagnostic accuracy scale-2 (QUADAS-2) was used to evaluate the quality of the enrolled studies. Moreover, publication bias was determined using the Deeks’ funnel plot. In total, 13 studies were enrolled for this meta-analysis (ranged between 2016 and 2020). Consequently, the CNN system had a satisfactory diagnostic performance in the field of CP detection (sensitivity: 0.848 [95% CI: 0.692–0.932]; specificity: 0.965 [95% CI: 0.946–0.977]; and AUC: 0.98 [95% CI: 0.96–0.99]) and CP classification (sensitivity: 0.943 [95% CI: 0.927–0.955]; specificity: 0.894 [95% CI: 0.631–0.977]; and AUC: 0.95 [95% CI: 0.93–0.97]). In comparison with human endoscopists, the CNN system was comparable to the expert but significantly better than the non-expert in the field of CP classification (CNN vs. expert: RDOR: 1.03, P = 0.9654; non-expert vs. expert: RDOR: 0.29, P = 0.0559; non-expert vs. CNN: 0.18, P = 0.0342). Therefore, the CNN system exhibited a satisfactory diagnostic performance for CP and could be used as a potential clinical diagnostic tool during colonoscopy.

Designs of colonoscopic adenoma detection trials: more positive results with tandem than with parallel studies - an analysis of studies on imaging techniques and mechanical devices

BACKGROUND AND AIMS

Adenoma detection rate (ADR) has been shown to correlate with interval cancers after screening colonoscopy and is commonly used as surrogate parameter for its outcome quality. ADR improvements by various techniques have been studied in randomised trials using either parallel or tandem methodololgy.

METHODS

A systematic literature search was done on randomised trials (full papers, English language) on tandem or parallel studies using either adenoma miss rates (AMR) or ADR as main outcome to test different novel technologies on imaging (new endoscope generation, narrow band imaging, iScan, Fujinon intelligent chromoendoscopy/blue laser imaging and wide angle scopes) and mechanical devices (transparent caps, endocuff, endorings and balloons). Available meta analyses were also screened for randomised studies.

RESULTS

Overall, 24 randomised tandem trials with AMR (variable definitions and methodology) and 42 parallel studies using ADR (homogeneous methodology) as primary outcome were included. Significant differences in favour of the new method were found in 66.7% of tandem studies (8222 patients) but in only 23.8% of parallel studies (28 059 patients), with higher rates of positive studies for mechanical devices than for imaging methods. In a random-effects model, small absolute risk differences were found, but these were double in magnitude for tandem as compared with parallel studies (imaging: tandem 0.04 (0.01, 0.07), parallel 0.02 (0.00, 0.04); mechanical devices: tandem 0.08 (0.00, 0.15), parallel 0.04 (0.01, 0.07)). Nevertheless, 94.2% of missed adenomas in the tandem studies were small (<1 cm) and/or non-advanced.

CONCLUSIONS

A tandem study is more likely to yield positive results than a simple parallel trial; this may be due to the use of different parameters, variable definitions and methodology, and perhaps also a higher likelihood of bias. Therefore, we suggest to accept positive results of tandem studies only if accompanied by positive results from parallel trials.

Artificial intelligence in endoscopy: Present and future perspectives

Artificial intelligence (AI) has been attracting considerable attention as an important scientific topic in the field of medicine. Deep-leaning (DL) technologies have been applied more dominantly than other traditional machine-learning methods. They have demonstrated excellent capability to retract visual features of objectives, even unnoticeable ones for humans, and analyze huge amounts of information within short periods. The amount of research applying DL-based models to real-time computer-aided diagnosis (CAD) systems has been increasing steadily in the GI endoscopy field. An array of published data has already demonstrated the advantages of DL-based CAD models in the detection and characterization of various neoplastic lesions, regardless of the level of the GI tract. Although the diagnostic performances and study designs vary widely, owing to a lack of academic standards to assess the capability of AI for GI endoscopic diagnosis fairly, the superiority of CAD models has been demonstrated for almost all applications studied so far. Most of the challenges associated with AI in the endoscopy field are general problems for AI models used in the real world outside of medical fields. Solutions have been explored seriously and some solutions have been tested in the endoscopy field. Given that AI has become the basic technology to make machines react to the environment, AI would be a major technological paradigm shift, for not only diagnosis but also treatment. In the near future, autonomous endoscopic diagnosis might no longer be just a dream, as we are witnessing with the advent of autonomously driven electric vehicles.

Optical diagnosis of diminutive polyps in the Dutch Bowel Cancer Screening Program: Are we ready to start?

Background and study aims  Implementation of optical diagnosis of diminutive polyps may potentially increase the efficacy and cost-effectiveness of colonoscopies. To adopt such strategy in clinical practice, the Preservation and Incorporation of Valuable endoscopic Innovations (PIVI) thresholds provide the basis to be met: ≥ 90 % negative predictive value (NPV) for diagnosis of adenomatous histology and ≥ 90 % agreement on surveillance intervals. We evaluated this within the Dutch Bowel Cancer Screening Program (BCSP). Patients and methods  Endoscopic and histological data were collected from participants of the national bowel cancer screening program with an unfavorable fecal immunochemical test referred for colonoscopy between February 2014 and August 2015 at four endoscopy centers. The "resect and discard" scenario was studied, resecting diminutive polyps without histological evaluation. Agreement between optical diagnosis and histological diagnosis was measured for surveillance intervals according to Dutch, European and American post-polypectomy surveillance guideline. Results  Fifteen certified endoscopists participated in this study and included 3028 diminutive polyps. In 2,330 patients both optical and histological diagnosis were available. Optical diagnosis of diminutive polyps showed NPV of 84 % (95 % CI 80-87) for adenomatous histology in the rectosigmoid. Applying the 'resect and discard' strategy resulted in 90.6 %, 91.2 %, 90.9 % agreement on surveillance intervals for the Dutch, European and American guideline respectively. Conclusion  Our data representing current clinical practice in the Dutch BCSP practice on optical diagnosis of diminutive polyps showed that accuracy of predicting histology remains challenging, and risk of incorrect optical diagnosis is still significant. Therefore, it is too early to safely implement these strategies.

Computer-assisted assessment of colonic polyp histopathology using probe-based confocal laser endomicroscopy

INTRODUCTION

Probe-based confocal laser endomicroscopy (pCLE) is a promising modality for classifying polyp histology in vivo, but decision making in real-time is hampered by high-magnification targeting and by the learning curve for image interpretation. The aim of this study is to test the feasibility of a system combining the use of a low-magnification, wider field-of-view pCLE probe and a computer-assisted diagnosis (CAD) algorithm that automatically classifies colonic polyps.

METHODS

This feasibility study utilized images of polyps from 26 patients who underwent colonoscopy with pCLE. The pCLE images were reviewed offline by two expert and five junior endoscopists blinded to index histopathology. A subset of images was used to train classification software based on the consensus of two GI histopathologists. Images were processed to extract image features as inputs to a linear support vector machine classifier. We compared the CAD algorithm's prediction accuracy against the classification accuracy of the endoscopists.

RESULTS

We utilized 96 neoplastic and 93 non-neoplastic confocal images from 27 neoplastic and 20 non-neoplastic polyps. The CAD algorithm had sensitivity of 95%, specificity of 94%, and accuracy of 94%. The expert endoscopists had sensitivities of 98% and 95%, specificities of 98% and 96%, and accuracies of 98% and 96%, while the junior endoscopists had, on average, a sensitivity of 60%, specificity of 85%, and accuracy of 73%.

CONCLUSION

The CAD algorithm showed comparable performance to offline review by expert endoscopists and improved performance when compared to junior endoscopists and may be useful for assisting clinical decision making in real time.

Optical Technologies for Endoscopic Real-Time Histologic Assessment of Colorectal Polyps: A Meta-Analysis

OBJECTIVES

Accurate, real-time, endoscopic risk stratification of colorectal polyps would improve decision-making and optimize clinical efficiency. Technologies to manipulate endoscopic optical outputs can be used to predict polyp histology in vivo; however, it remains unclear how accuracy has progressed and whether it is sufficient for routine clinical implementation.

METHODS

A meta-analysis was conducted by searching MEDLINE, Embase, and the Cochrane Library. Studies were included if they prospectively deployed an endoscopic optical technology for real-time in vivo prediction of adenomatous colorectal polyps. Polyposis and inflammatory bowel diseases were excluded. Bayesian bivariate meta-analysis was performed, presenting 95% confidence intervals (CI).

RESULTS

One hundred two studies using optical technologies on 33,123 colorectal polyps were included. Digital chromoendoscopy differentiated neoplasia (adenoma and adenocarcinoma) from benign polyps with sensitivity of 92.2% (90.6%-93.9% CI) and specificity of 84.0% (81.5%-86.3% CI), with no difference between constituent technologies (narrow-band imaging, Fuji intelligent Chromo Endoscopy, iSCAN) or with only diminutive polyps. Dye chromoendoscopy had sensitivity of 92.7% (90.1%-94.9% CI) and specificity of 86.6% (82.9%-89.9% CI), similarly unchanged for diminutive polyps. Spectral analysis of autofluorescence had sensitivity of 94.4% (84.0%-99.1% CI) and specificity of 50.9% (13.2%-88.8% CI). Endomicroscopy had sensitivity of 93.6% (85.3%-98.3% CI) and specificity of 92.5% (81.8%-98.1% CI). Computer-aided diagnosis had sensitivity of 88.9% (74.2%-96.7% CI) and specificity of 80.4% (52.6%-95.7% CI). Prediction confidence and endoscopist experience alone did not significantly improve any technology. The only subgroup to demonstrate a negative predictive value for adenoma above 90% was digital chromoendoscopy, making high confidence predictions of diminutive recto-sigmoid polyps. Chronologic meta-analyses show a falling negative predictive value over time. A significant publication bias exists.

DISCUSSION

This novel approach to meta-analysis demonstrates that existing optical technologies are increasingly unlikely to allow safe "resect and discard" strategies and that step-change innovation may be required. A "diagnose and leave" strategy may be supported for diminutive recto-sigmoid polyps diagnosed with high confidence; however, limitations exist in the evidence base for this cohort.

Breath analysis of cancer in the present and the future

Most of the currently used diagnostics for cancerous diseases have yet to meet the standards of screening, as they are insufficiently accurate and/or invasive and risky. In this review, we describe the rationale, the progress made to date, and the potential of analysing the exhaled volatile organic compounds as a pathway for enabling early diagnosis of cancer and, therefore, for achieving better clinical prognosis and survival rates. The review highlights the major advancements made in this field, from fundamentals, up to translational phases and clinical trials, with a special emphasis on sensing platforms based on nanomaterials. The prospects for breath analysis in early cancerous disease are presented and discussed.

Endoscopic characterization of small colonic polyps: baseline performance of experienced endoscopists is no different to that of medical students

Background  Studies examining the impact of training modules on characterization of diminutive colonic polyps (DCP) show varying results. Aim  We aimed to assess the impact of a novel web-based training module on the accuracy of in vivo characterization of DCPs using different imaging modalities. Differences between groups with varying degrees of endoscopic experience were also assessed. Methods  In total, 90 images of 30 DCPs viewed with high definition white light (HDWL), i-Scan, and indigo carmine chromoendoscopy were included in an online test module. Testing was undertaken before and after completing a novel web-based in vivo characterization training module. In total, 21 subjects (medical students (MS), gastroenterology trainees (GT), and gastroenterology consultants (GC)) undertook the tests and training module. Results  No statistically significant difference in overall accuracy was found between the three groups either pre- (MS 59.1 %, GR 65.7 %, GC 62.4 %, P  = ns for all three comparisons) or post-training (MS 69.2 %, GR 71.1 %, GC 71.3 %, P  = ns for all three comparisons). Accuracy improved significantly for all three groups post-training ( P  < 0.001) as did interobserver agreement. No significant differences in accuracy between modalities were found pre-training (HDWL 64.8 %, i-Scan 60.0 %, chromoendoscopy 62.2 %, P  = ns). Post-training accuracy with HDWL and chromoendoscopy was better than with i-Scan (HDWL 72.9 % vs i-Scan 65.1 %, P  = 0.002; i-Scan 65.1 % vs chromoendoscopy 73.7 %, P  < 0.001). The proportion of high confidence predictions increased from 25.7 % to 41.5 %, with a high confidence prediction accuracy of 81.7 %. Conclusions  Skills for in vivo characterization of DCPs are not acquired through endoscopic experience alone. A novel web-based training intervention results in modest improvements in accuracy with further improvements likely to require more prolonged training.

Near focus NBI endoscopy plus acetic acid for optical polyp characterization in the colorectum - A proof of principle study

Background and study aim: Optical polyp characterization (OPC) in the colorectum is an upcoming challenge for endoscopists. Narrow band imanging (NBI) has been proposed to be helpful for OPC. However, data from clinical studies have shown that quality of OPC differs markedly between endoscopists. The aim of this study was to test the value of a combined NBI plus acetic acid (NBI + AA) approach for OPC in the colorectum. Patients and methods: This was a prospective, single-arm study at a tertiary referral center in Germany. The study was designed as a proof of principle study. Initially polyps were characterized using High-definition white light (HDWL) only. Additionally, the same polyps were investigated using NBI + AA (1.5% solution) in order to predict polyp pathology in a real time setting. The near focus function was used for both HDWL and NBI + AA assessment. The primary endpoint was accuracy of colorectal polyp prediction when using NBI + AA. Results: A total of 63 polyps were detected in 55 patients. NBI + AA based accuracy of real-time predictions was 85.5% compared to 80.6% using HDWL (p = .450). Accuracy was 90.2% in the high confidence setting for both NBI + AA and HDWL predictions. A higher share of polyps were assessed with high confidence when using NBI + AA compared to HDWL (p = .006). The use of NBI + AA led to a better identification of polyp margins (p < .001) compared to HDWL. Conclusions: The use of acetic acid led to a high level of accuracy and confidence in the prediction of polyp histology. These data justify further investigation in a randomized controlled study.

Should We Resect and Discard Low Risk Diminutive Colon Polyps

Diminutive colorectal polyps <5 mm are very common and almost universally benign. The current strategy of resection with histological confirmation of all colorectal polyps is costly and may increase the risk of colonoscopy. Accurate, optical diagnosis without histology can be achieved with currently available endoscopic technologies. The American Society of Gastrointestinal Endoscopy Preservation and Incorporation of Valuable endoscopic Innovations supports strategies for optical diagnosis of small non neoplastic polyps as long as two criteria are met. For hyperplastic appearing polyps <5 mm in recto-sigmoid colon, the negative predictive value should be at least 90%. For diminutive low grade adenomatous appearing polyps, a resect and discard strategy should be sufficiently accurate such that post-polypectomy surveillance recommendations based on the optical diagnosis, agree with a histologically diagnosis at least 90% of the time. Although the resect and discard as well as diagnose and leave behind approach has major benefits with regard to both safety and cost, it has yet to be used widely in practice. To fully implement such as strategy, there is a need for better-quality training, quality assurance, and patient acceptance. In the article, we will review the current state of the science on optical diagnose of colorectal polyps and its implications for colonoscopy practice.

Diagnostic accuracy of i-scan image enhancement for real-time endoscopic diagnosis of small colorectal polyps: a meta-analysis

OBJECTIVE

i-Scan is a digital image enhancement technology, reported to improve diagnostic performance during endoscopy. Previous studies have investigated the accuracy of i-scan for distinguishing between neoplastic and non-neoplastic colonic polyps and suggested diagnostic accuracy close to that required for use in routine clinical practice. The aim of this study was to perform a meta-analysis of the available literature investigating diagnostic accuracy for i-scan optical diagnosis when made in real time for colorectal polyps <10 mm in size.

DATA SOURCES

The databases of Medline, Embase and the Cochrane Library were searched for relevant studies.

METHODS

A bivariate random effects model was used to produce pooled sensitivity and specificity values, and univariable meta-regression was applied for subgroup analysis.

RESULTS

The meta-analysis included 15 studies, and diagnosis of 2817 polyps. The area under the hierarchical summary receiver-operating characteristic curve was 0.96. The pooled sensitivity of i-scan optical diagnosis was 0.92 (95% confidence interval 0.85-0.95). The specificity was 0.90 (95% confidence interval 0.83-0.94).

CONCLUSIONS

This meta-analysis updates and summarizes the available evidence concerning the diagnostic performance of i-scan for small colorectal polyps. An acceptable degree of accuracy was found, showing potential to support a 'resect and discard' strategy for colonic polyps. There was not found to be a significant difference in diagnostic performance between different clinical settings (i.e. teaching hospitals or general hospitals).

Quantitative analysis of in vivo high-resolution microendoscopic images for the detection of neoplastic colorectal polyps

Colonoscopy is routinely performed for colorectal cancer screening but lacks the capability to accurately characterize precursor lesions and early cancers. High-resolution microendoscopy (HRME) is a low-cost imaging tool to visualize colorectal polyps with subcellular resolution. We present a computer-aided algorithm to evaluate HRME images of colorectal polyps and classify neoplastic from benign lesions. Using histopathology as the gold standard, clinically relevant features based on luminal morphology and texture are quantified to build the classification algorithm. We demonstrate that adenomatous polyps can be identified with a sensitivity and specificity of 100% and 80% using a two-feature linear discriminant model in a pilot test set. The classification algorithm presented here offers an objective framework to detect adenomatous lesions in the colon with high accuracy and can potentially improve real-time assessment of colorectal polyps.

Optical classification of neoplastic colorectal polyps - a computer-assisted approach (the COACH study)

BACKGROUND AND AIMS

Clinical data suggest that the quality of optical diagnoses of colorectal polyps differs markedly among endoscopists. The aim of this study was to develop a computer program that was able to differentiate neoplastic from non-neoplastic polyps using unmagnified endoscopic pictures.

METHODS

During colonoscopy procedures polyp photographies were performed using the unmagnified high-definition white light and narrow band image mode. All detected polyps (n = 275) were resected and sent to pathology. Histopathological diagnoses served as the ground truth. Machine learning was used in order to generate a computer-assisted optical biopsy (CAOB) approach. In the test phase pictures were presented to CAOB in order to obtain optical diagnoses. Altogether 788 pictures were available (602 for training the machine learning algorithm and 186 for CAOB testing). All test pictures were also presented to two experts in optical polyp characterization. The primary endpoint of the study was the accuracy of CAOB diagnoses in the test phase.

RESULTS

A total of 100 polyps (of these 52% neoplastic) were used in the CAOB test phase. The mean size of test polyps was 4 mm. Accuracy of the CAOB approach was 78.0%. Sensitivity and negative predictive value were 92.3% and 88.2%, respectively. Accuracy obtained by two expert endoscopists was 84.0% and 77.0%. Regarding accuracy of optical diagnoses CAOB predictions did not differ significantly compared to experts (p = .307 and p = 1.000, respectively).

CONCLUSIONS

CAOB showed good accuracy on the basis of unmagnified endoscopic pictures. Performance of CAOB predictions did not differ significantly from experts' decisions. The concept of computer assistance for colorectal polyp characterization needs to evolve towards a real-time application prior of being used in a broader set-up.

Mis-sizing of Adenomatous Polyps is Common among Endoscopists and Impacts Colorectal Cancer Screening Recommendations

Background/Aims

To determine the accuracy of identifying ≥6-mm adenomatous polyps during colonoscopy and define its impact on subsequent interval screening.

Methods

We conducted a retrospective study of patients who underwent colonoscopies at Banner University Medical Center, Tucson from 2011 to 2015. All patients with ≥6-mm adenomatous polyps based on their colonoscopy report were included. Adenomatous polyps were excluded if they did not meet the criteria. Discrepancies in the polyp size were determined by calculating the percentage of size variation (SV). Clinical mis-sizing was defined as SV >33%.

Results

The polyps analyzed were predominantly <10 mm in size. Approximately 13% of the examined polyps met the inclusion criteria, and 40.7% of the adenomas were ≥10 mm. A total of 189 ≥6-mm adenomatous polyps were collected from 10 different gastroenterologists and a colorectal surgeon. Adenomatous polyps were clinically mis-sized in 56.6% of cases and overestimated in 71.4%. Among the adenomas reviewed, 22% of mis-sized polyps and 11% of non-mis-sized polyps resulted in an inappropriate surveillance interval.

Conclusions

We found that more than half of ≥6-mm adenomatous polyps are mis-sized and that there is a tendency to overestimate adenoma size among endoscopists. This frequently leads to inappropriate intervals of surveillance colonoscopy.

I-scan optical enhancement for the in vivo prediction of diminutive colorectal polyp histology: Results from a prospective three-phased multicentre trial

Background and aims

Dye-less chromoendoscopy is an emerging technology for colorectal polyp characterization. Herein, we investigated whether the newly introduced I-scan optical enhancement (OE) can accurately predict polyp histology in vivo in real-time.

Methods

In this prospective three-phased study, 84 patients with 230 diminutive colorectal polyps were included. During the first two study phases, five endoscopists assessed whether analysis of polyp colour, surface and vascular pattern under i-scan OE can differentiate in vivo between adenomatous and hyperplastic polyps. Finally, junior and experienced endoscopists (JE, EE, each n = 4) not involved in the prior study phases made a post hoc diagnosis of polyp histology using a static i-scan OE image database. Histopathology was used as a gold-standard in all study phases.

Results

The overall accuracy of i-scan OE for histology prediction was 90% with a sensitivity, specificity, positive (PPV) and negative prediction value (NPV) of 91%, 90%, 86% and 94%, respectively. In high confidence predictions, the diagnostic accuracy increased to 93% with sensitivity, specificity, PPV and NPV of 94%, 91%, 89% and 96%. Colonoscopy surveillance intervals were predicted correctly in ≥ 90% of patients. In the post hoc analysis EE predicted polyp histology under i-scan OE with an overall accuracy of 91%. After a single training session, JE achieved a comparable diagnostic performance for predicting polyp histology with i-scan OE.

Conclusion

The histology of diminutive colorectal polyps can be accurately predicted with i-scan OE in vivo in real-time. Furthermore, polyp differentiation with i-scan OE appears to require only a short learning curve.

Randomized Controlled Trial of Self-directed Versus In-Classroom Education of Narrow Band Imaging in Diagnosing Colorectal Polyps Using the NICE Criteria

BACKGROUND

The optimal method for teaching NBI International Colorectal Endoscopic (NICE) criteria to medical trainees is unknown.

METHODS

Trainees (medical students, residents, and gastroenterology fellows) were randomized to 2 groups (in-classroom vs. self-directed training). Teaching phase: A standardized presentation was developed about narrow band imaging (NBI) and NICE criteria. The in-class teaching group attended a single live-teaching session (with NBI expert). The self-directed training group was provided with the same educational tool with recorded audio. Testing phase: All participants provided their predicted histology and their level of confidence. After completing initial 10 clips, the in-class teaching group received live feedback (NBI expert), whereas the self-teaching group received automated audio feedback. All participants then reviewed the next 30 NBI videos. The diagnostic performance of NBI in predicting histology was compared between the 2 groups.

RESULTS

Twenty medical trainees (8 students, 8 residents, and 4 gastroenterology fellows) participated in the study. The overall accuracy, sensitivity, specificity, and negative predictive value in using NBI to predict histology were: 79.0% [95% confidence interval (CI), 76.2-81.8], 69.5% (95% CI, 65.0-74.0), 88.5% (95% CI, 85.3-91.6), and 74.4% (95% CI, 70.4-78.3). There were no significant differences in the performance characteristics between the in-classroom and self-directed groups for all responses including those answered with high confidence.

CONCLUSIONS

Using a standardized educational tool, the accuracy of distinguishing adenomatous versus hyperplastic colon polyps using NBI between the in-class teaching and self-directed learning were similar. This suggests that both training methods can be utilized for the education of medical trainees in the use of NICE criteria.

Effects of Training and Feedback on Accuracy of Predicting Rectosigmoid Neoplastic Lesions and Selection of Surveillance Intervals by Endoscopists Performing Optical Diagnosis of Diminutive Polyps

BACKGROUND & AIMS

Real-time differentiation of diminutive polyps (1-5 mm) during endoscopy could replace histopathology analysis. According to guidelines, implementation of optical diagnosis into routine practice would require it to identify rectosigmoid neoplastic lesions with a negative predictive value (NPV) of more than 90%, using histologic findings as a reference, and agreement with histology-based surveillance intervals for more than 90% of cases.

METHODS

We performed a prospective study with 39 endoscopists accredited to perform colonoscopies on participants with positive results from fecal immunochemical tests in the Bowel Cancer Screening Program at 13 centers in the Netherlands. Endoscopists were trained in optical diagnosis using a validated module (Workgroup serrAted polypS and Polyposis). After meeting predefined performance thresholds in the training program, the endoscopists started a 1-year program (continuation phase) in which they performed narrow band imaging analyses during colonoscopies of participants in the screening program and predicted histological findings with confidence levels. The endoscopists were randomly assigned to groups that received feedback or no feedback on the accuracy of their predictions. Primary outcome measures were endoscopists' abilities to identify rectosigmoid neoplastic lesions (using histology as a reference) with NPVs of 90% or more, and selecting surveillance intervals that agreed with those determined by histology for at least 90% of cases.

RESULTS

Of 39 endoscopists initially trained, 27 (69%) completed the training program. During the continuation phase, these 27 endoscopists performed 3144 colonoscopies in which 4504 diminutive polyps were removed. The endoscopists identified neoplastic lesions with a pooled NPV of 90.8% (95% confidence interval 88.6-92.6); their proposed surveillance intervals agreed with those determined by histologic analysis for 95.4% of cases (95% confidence interval 94.0-96.6). Findings did not differ between the group that did vs did not receive feedback. Sixteen endoscopists (59%) identified rectosigmoid neoplastic lesions with NPVs greater than 90% and selected surveillance intervals in agreement with those determined from histology for more than 90% of patients.

CONCLUSIONS

In a prospective study following a validated training module, we found that a selected group of endoscopists identified rectosigmoid neoplastic lesions with pooled NPVs greater than 90% and accurately selected surveillance intervals for more than 90% of patients over the course of 1 year. Providing regular interim feedback on the accuracy of neoplastic lesion prediction and surveillance interval selection did not lead to differences in those endpoints. Monitoring is suggested, as individual performance varied. ClinicalTrials.gov no: NCT02516748; Netherland Trial Register: NTR4635.

Simplifying Resect and Discard Strategies for Real-Time Assessment of Diminutive Colorectal Polyps

BACKGROUND & AIMS

During endoscopy, the resect and discard strategy, if performed with high confidence, can be used to determine histologic features of diminutive colorectal polyps (5 mm or less). These polyps can then be removed and discarded without pathology assessment. However, the complexities of real-time optical assessment and follow-up management have provided challenges to widespread use of this approach. We aimed to determine the outcomes of simple alternative strategies, in which all diminutive polyps can be resected and discarded.

METHODS

We collected data from 2 previous studies that used narrow-band imaging to assess polyps, performed at 5 medical centers (1658 patients with 2285 diminutive polyps; 15 endoscopists). We compared 3 resect and discard strategies: the currently used optical strategy, which relies on high confidence optical assessment of all diminutive polyps; a location-based strategy that classifies all recto-sigmoid diminutive polyps a priori as hyperplastic and all polyps proximal to the recto-sigmoid colon a priori as neoplastic; and a simplified optical strategy, in which all recto-sigmoid diminutive polyps are classified as hyperplastic unless confidently assessed as neoplastic, and all polyps proximal to the recto-sigmoid colon are classified as neoplastic unless confidently assessed as hyperplastic polyps. The primary outcome was the agreement of the surveillance interval calculated for each strategy with the surveillance interval determined by pathology analysis.

RESULTS

The proportion of surveillance intervals that agreed with pathology-based surveillance recommendations was slightly higher when the optical strategy was used compared to the location-based strategy or simplified optical strategy (94% vs 89% and 90%, respectively; P < .001). When the 5-10 year recommendations for patients with low-risk polyps were applied as a 10-year surveillance interval, all 3 strategies resulted in surveillance interval agreement compared to pathology above 90% (the quality benchmark). Use of the simplified or location-based strategy could have avoided pathology analysis for 77% of all polyps, compared to 59% if the optical strategy was used (P < .001). In addition, a higher proportion of patients could receive recommendations immediately after colonoscopy with use of the simplified or location based strategy (65%) compared to the optical strategy (40%) (P < .001).

CONCLUSION

A location-based and a simplified optical resect and discard strategy produced surveillance recommendations that were in agreement with those from pathology analysis for at least 90% of patients, assuming a 10-year surveillance interval for patients with low-risk polyps. These strategies could further reduce the number of pathology examinations and provide more patients with immediate surveillance recommendations. Optical assessment might be reduced or might not be required for resect and discard. Clintrials.gov no: NCT01935180 and NCT01288833.

Advances in CRC Prevention: Screening and Surveillance

Colorectal cancer (CRC) is among the most commonly diagnosed cancers and causes of death from cancer across the world. CRC can, however, be detected in asymptomatic patients at a curable stage, and several studies have shown lower mortality among patients who undergo screening compared with those who do not. Using colonoscopy in CRC screening also results in the detection of precancerous polyps that can be directly removed during the procedure, thereby reducing the incidence of cancer. In the past decade, convincing evidence has appeared that the effectiveness of colonoscopy as CRC prevention tool is associated with the quality of the procedure. This review aims to provide an up-to-date overview of recent efforts to improve colonoscopy effectiveness by enhancing detection and improving the completeness and safety of resection of colorectal lesions.

Detection and characterization of colorectal polyps using high-definition white light and i-Scan: Evidence-based consensus recommendations using a modified Delphi process

Background

i-Scan is an image enhancement modality, which provides enhanced views of mucosal structures and vascular patterns.

Methods

A modified Delphi process was used to develop a series of evidence-based statements on the role of high-definition white light (HDWL) and i-Scan for the detection and diagnosis of colorectal neoplasms. Each statement was voted to achieve consensus (i.e. >80% agreement).

Results

Seven proposed statements achieved consensus: (1) HDWL is recommended rather than standard definition (SD) for detection and diagnosis of colorectal neoplasms; (2) HDWL colonoscopy with i-Scan improves polyp and adenoma detection rates when compared with SD colonoscopy; (3) HDWL + i-Scan is superior to HDWL alone for the optical diagnosis of colorectal neoplasms; (4) HDWL + i-Scan in expert hands meets American Society for Gastrointestinal Endoscopy (ASGE) in the Preservation and Incorporation of Valuable Endoscopic Innovations (PIVI) standards for optical diagnosis of diminutive neoplasms; (5) HDWL + i-Scan in non-expert hands does not meet ASGE PIVI standards for optical diagnosis of diminutive neoplasms; (6) optical diagnosis of polyps with i-Scan has a learning curve and needs systematic training; and (7) the performance of i-Scan for the in vivo diagnosis of colorectal neoplasms is similar to Narrow Band Imaging (NBI) and Fuji Intelligent Chromo Endoscopy (FICE).

Conclusions

Seven proposed statements on the use of HDWL and i-Scan for the detection and diagnosis of colorectal neoplasms achieved consensus.

Acetic acid-guided biopsies in Barrett's surveillance for neoplasia detection versus non-targeted biopsies (Seattle protocol): A feasibility study for a randomized tandem endoscopy trial. The ABBA study

BACKGROUND AND STUDY AIMS

Barrett's esophagus is a potentially pre-cancerous condition, affecting 375,000 people in the UK. Patients receive a 2-yearly endoscopy to detect cancerous changes, as early detection and treatment results in better outcomes. Current treatment requires random mapping biopsies along the length of Barrett's, in addition to biopsy of visible abnormalities. As only 13 % of pre-cancerous changes appear as visible nodules or abnormalities, areas of dysplasia are often missed. Acetic acid chromoendoscopy (AAC) has been shown to improve detection of pre-cancerous and cancerous tissue in observational studies, but no randomized controlled trials (RCTs) have been performed to date.

PATIENTS AND METHODS

A "tandem" endoscopy cross-over design. Participants will be randomized to endoscopy using mapping biopsies or AAC, in which dilute acetic acid is sprayed onto the surface of the esophagus, highlighting tissue through an whitening reaction and enhancing visibility of areas with cellular changes for biopsy. After 4 to 10 weeks, participants will undergo a repeat endoscopy, using the second method. Rates of recruitment and retention will be assessed, in addition to the estimated dysplasia detection rate, effectiveness of the endoscopist training program, and rates of adverse events (AEs). Qualitative interviews will explore participant and endoscopist acceptability of study design and delivery, and the acceptability of switching endoscopic techniques for Barrett's surveillance.

RESULTS

Endoscopists' ability to diagnose dysplasia in Barrett's esophagus can be improved. AAC may offer a simple, universally applicable, easily-acquired technique to improve detection, affording patients earlier diagnosis and treatment, reducing endoscopy time and pathology costs. The ABBA study will determine whether a crossover "tandem" endoscopy design is feasible and acceptable to patients and clinicians and gather outcome data to power a definitive trial.

Targeting Mucosal Endothelin-A-Receptor Expression by Fluorescence Endoscopy is Feasible to Detect and Characterize Colitis-Associated Cancer in Mice

BACKGROUND

To facilitate onsite decision-making during endoscopy, both accurate detection and in vivo characterization of preneoplasia are prerequisites. However, no endoscopy technique is available that meets both demands satisfactorily. We evaluated endothelin-receptor A (ETAR)-guided fluorescence endoscopy (FE) in vivo and fluorescence reflectance imaging (FRI) ex vivo for detection and characterization of early dysplastic colitis-associated colonic lesions.

METHODS

Colorectal cancerogenesis was investigated in the inflammatory driven AOM-DSS model and spontaneous adenoma development in ApcMin mice. A Cy5.5-labeled nonpeptidic ETAR-specific imaging probe was injected intravenously to assess tumor development in vivo by white light endoscopy (WLE) and FE. Ex vivo tumors were evaluated by FRI, histological examination, and western blot analysis. In addition, tissue samples from patients with colitis-associated malignant and nonmalignant mucosal alterations were analyzed. Specificity experiments were performed using an unspecific Cy3.5-glycine tracer.

RESULTS

Overall, 62 adenomas were observed. FE was able to detect and quantify ETAR expression targeting the ETAR-specific photoprobe. A significantly higher fluorescent contrast was detected in colonic adenomas compared to adjacent nonmalignant mucosa by FE (64.3 ± 7.9 vs. 56.6. ± 7.0; P < 0.001). These results were confirmed by FRI examination, immunochemistry, and western blot analysis. Additionally, ETAR expression in samples from human patients with colitis-associated cancer was highly elevated compared to nonmalignant alterations. Specificity experiments indicated a high binding-specificity of the applied ETAR photoprobe (1.4 ± 0.3 vs. 2.5 ± 0.7; P < 0.001).

CONCLUSIONS

We introduced ETAR guided FE in mice for successful in vivo detection and characterization of colorectal neoplasia on a molecular level.

Implementation of real-time probe-based confocal laser endomicroscopy (pCLE) for differentiation of colorectal polyps during routine colonoscopy

BACKGROUND AND AIMS

 Probe-based confocal laser endomicroscopy (pCLE) is used to differentiate between neoplastic and non-neoplastic colorectal polyps during colonoscopy. We aimed to assess the accuracy of two endoscopists starting to use real-time pCLE for differentiation of colorectal polyps and to determine the negative predictive value (NPV) for neoplasia in polyps ≤ 5 mm.

METHODS

 Patients undergoing colonoscopy in a tertiary hospital were included in this prospective trial. After a training session, two colonoscopists assessed 50 polyps between August 2012 and April 2014. They sequentially used narrow-band imaging (NBI) and real-time pCLE to differentiate non-adenomatous, adenomatous, and carcinomatous polyps during colonoscopy. Histologic diagnosis by a gastrointestinal pathologist was the gold standard. Results were compared to post-hoc pCLE by a panel of gastroenterologists and pathologists.

RESULTS

 The accuracy of real-time pCLE was 76 %, compared to 73 % for NBI, and was not significantly different between the first 50 cases (74 %) and the last 50 cases (78 %, P  = 0.64). The accuracy in polyps > 5 mm was 87 % versus 59 % in polyps ≤ 5 mm ( P  = 0.04) and increased from 45 % (13/29) in poor quality images to 86 % (44/51) in fair quality images and 95 % (19/20) in good quality images ( P  < 0.01). The post-hoc pCLE accuracy was 62 %. The NPV for polyps ≤ 5 mm was 58 % for real-time pCLE and 54 % for post-hoc pCLE.

CONCLUSION

 Although a fair accuracy of real-time pCLE for differentiation of colorectal polyps can be achieved within 50 cases, low NPV and difficulty in obtaining high-quality pCLE images hamper implementation in routine clinical practice.

Current standards and new developments of colorectal polyp management and resection techniques

Colonoscopy and endoscopic removal of precancerous polyps play an important role in colorectal cancer (CRC) prevention. Improved endoscopes and quality standards have led to an increasing polyp and adenoma detection rate. Optimal polyp resection techniques and management strategies are key for an effective colonoscopy practice. Areas covered: Strategies for how to improve diminutive polyp (polyps up to 5 mm in size) management are discussed because of their high prevalence. Systematic removal of diminutive polyps leads to increasing costs of colonoscopy practice, while the effect on colorectal cancer prevention might be negligible. Furthermore, polypectomy recommendations for mid-size and large polyps are provided. For all larger polyps larger, complete and safe resection is mandatory to avoid post colonoscopy cancers. The focus for managing such larger polyps is to use new techniques (i.e. cold snares) and to attempt complete removal and to reduce post-polypectomy complications. Expert commentary: The resect-and-discard strategy is a promising management strategy for diminutive polyps. However, modification of this approach might be required in order to make widespread adoption feasible. Cold snare polypectomy is a promising new approach for small polyp resection. For resection of large polyps adequate treatment recommendations with regard to endoscopic mucosal resection and complication prevention are provided.

Raman fiber-optical method for colon cancer detection: Cross-validation and outlier identification approach

Endoscopy plays a major role in early recognition of cancer which is not externally accessible and therewith in increasing the survival rate. Raman spectroscopic fiber-optical approaches can help to decrease the impact on the patient, increase objectivity in tissue characterization, reduce expenses and provide a significant time advantage in endoscopy. In gastroenterology an early recognition of malign and precursor lesions is relevant. Instantaneous and precise differentiation between adenomas as precursor lesions for cancer and hyperplastic polyps on the one hand and between high and low-risk alterations on the other hand is important. Raman fiber-optical measurements of colon biopsy samples taken during colonoscopy were carried out during a clinical study, and samples of adenocarcinoma (22), tubular adenomas (141), hyperplastic polyps (79) and normal tissue (101) from 151 patients were analyzed. This allows us to focus on the bioinformatic analysis and to set stage for Raman endoscopic measurements. Since spectral differences between normal and cancerous biopsy samples are small, special care has to be taken in data analysis. Using a leave-one-patient-out cross-validation scheme, three different outlier identification methods were investigated to decrease the influence of systematic errors, like a residual risk in misplacement of the sample and spectral dilution of marker bands (esp. cancerous tissue) and therewith optimize the experimental design. Furthermore other validations methods like leave-one-sample-out and leave-one-spectrum-out cross-validation schemes were compared with leave-one-patient-out cross-validation. High-risk lesions were differentiated from low-risk lesions with a sensitivity of 79%, specificity of 74% and an accuracy of 77%, cancer and normal tissue with a sensitivity of 79%, specificity of 83% and an accuracy of 81%. Additionally applied outlier identification enabled us to improve the recognition of neoplastic biopsy samples.

Polyp Resection - Controversial Practices and Unanswered Questions

Detection and complete removal of precancerous neoplastic polyps are central to effective colorectal cancer screening. The prevalence of neoplastic polyps in the screening population in the United States is likely >50%. However, most persons with neoplastic polyps are never destined to develop cancer, and do not benefit for finding and removing polyps, and may only be harmed by the procedure. Further 70-80% of polyps are diminutive (≤5 mm) and such polyps almost never contain cancer. Given the questionable benefit, the high-cost and the potential risk changing our approach to the management of diminutive polyps is currently debated. Deemphasizing diminutive polyps and shifting our efforts to detection and complete removal of larger and higher-risk polyps deserves discussion and study. This article explores three controversies, and emerging concepts related to endoscopic polyp resection. First, we discuss challenges of optical resect-and-discard strategy and possible alternatives. Second, we review recent studies that support the use of cold snare resection for ≥5 mm polyps. Thirdly, we examine current evidence for prophylactic clipping after resection of large polyps.

Endoscopic Improvement of the Adenoma Detection Rate during Colonoscopy - Where Do We Stand in 2015?

BACKGROUND

The presence of colorectal adenomas is considered a major risk factor for colorectal cancer development. The implementation of screening colonoscopy programs in the Western world has led to a substantial reduction of colorectal cancer death. Many efforts have been made to reduce the adenoma miss rates by the application of new endoscopic devices and techniques for better adenoma visualization.

SUMMARY

This special review gives the readership an overview of current endoscopic innovations that can aid in the increase of the adenoma detection rate (ADR) during colonoscopy. These innovations include the use of devices like EndoCuff® and EndoRings® as well as new technical equipment like third-eye endoscope® and full-spectrum endoscopy (FUSE®).

KEY MESSAGE

Technical improvements and newly developed accessories are able to improve the ADR. However, additional costs and a willingness to invest into potentially expensive equipment might be necessary. Investigator-dependent skills remain the backbone in the ADR detection.

Colonic lesion characterisation skills among UK endoscopists and the impact of a brief training intervention

OBJECTIVE

To assess UK gastroenterology registrars' and consultants' competence in in vivo characterisation of polyps, plus the impact of a dedicated colonic lesion characterisation training intervention.

DESIGN

Prospective evaluation of a computer-based colonic lesion training module.

SETTING

Three UK general hospitals.

PATIENTS

High-quality endoscopic images obtained during colonoscopy in a previous study.

INTERVENTIONS

30 min computer-based training module covering in vivo characterisation of colonic lesions viewed under white light, chromoendoscopy and magnification chromoendoscopy.

MAIN OUTCOME MEASURES

Accuracy of characterisation of colonic lesions (hyperplastic vs adenoma vs cancer) before and after training and differences between groups (bowel cancer screening (BCS) nurses vs gastroenterology trainees vs consultant gastroenterologists).

RESULTS

Mean accuracy pretraining was 61.1%, 67.6% and 60.0% for the trainee, consultant and nurse groups respectively with no significant difference between the groups. Mean accuracy post-training improved significantly to 71.2%, 72.6% and 67.2% for the trainee, consultant and nurse groups (p<0.001 vs pretraining) with no significant difference between the three groups. Mean sensitivity and specificity improved significantly for the 15 participants overall.

CONCLUSIONS

The baseline level of colonic lesion characterisation skills is limited for gastroenterology consultants and trainees and does not differ from that of non-endoscopist BCS nurses. Accuracy of lesion characterisation can be modestly improved with a brief computer-based training intervention. Lesion characterisation should become a standard part of training in colonoscopy, and should be learnt alongside technical skills for endoscope handing and therapeutic procedures.

Expert opinions and scientific evidence for colonoscopy key performance indicators

Colonoscopy is a widely performed procedure with procedural volumes increasing annually throughout the world. Many procedures are now performed as part of colorectal cancer screening programmes. Colonoscopy should be of high quality and measures of this quality should be evidence based. New UK key performance indicators and quality assurance standards have been developed by a working group with consensus agreement on each standard reached. This paper reviews the scientific basis for each of the quality measures published in the UK standards.

People with low serum folate levels have higher risk of colorectal adenoma/advanced colorectal adenoma occurrence and recurrence in China

Objective

To investigate the potential association between serum folate levels and colorectal adenoma (CRA) occurrence and recurrence.

Methods

This prospective study measured baseline serum folate levels in outpatients who were screened for CRA using colonoscopy. Participants were then randomly selected to produce one group with CRA and one without CRA. These two subgroups underwent further follow-up observations of colonoscopy to determine the occurrence of new and recurrent CRA.

Results

A total of 1310 participants were screened at baseline: 888 were healthy subjects without CRA; and 422 had CRA. Two subgroups were randomly selected (n = 200 per group) for follow-up. In the overall population, baseline serum folate levels were significantly lower in patients with CRA or advanced CRA (A-CRA) compared with healthy participants without CRA. Similar findings were shown for the follow-up study in terms of the association between CRA and A-CRA occurrence and recurrence and baseline serum folate levels. After controlling for confounders, increased serum folate was associated with a reduced risk of occurrence of CRA (odds ratio [OR] 0.993, 95% confidence interval [CI] 0.924, 1.066) and recurrence of CRA (OR 0.749, 95% CI 0.322, 1.742).

Conclusions

Higher serum folate levels may be protective against CRA and/or A-CRA.

Optical diagnosis of colorectal neoplasia: A Western perspective

Optical diagnosis is an emerging paradigm in Western endoscopic practice for the colonoscopic management of diminutive polyps, and includes two complementary clinical strategies: 'resect and discard', in which diminutive high-confidence adenomas are identified, and then removed and discarded without pathological assessment; and 'diagnose and leave', where diminutive high-confidence hyperplastic polyps are identified in the rectosigmoid and then left without resection or biopsy. Like other aspects of colonoscopy performance, adoption of optical diagnosis in Western practice is limited by operator dependency and variation in clinical effectiveness. There is substantial potential for optical diagnosis of colorectal neoplasia during colonoscopy to alleviate the rising costs of health care in the West. However, operator dependence in diagnostic performance together with critical system factors such as informed consent, credentialing, medical legal support and reimbursement incentives must be overcome before optical diagnosis of diminutive lesions is considered for widespread adoption in Western clinical practice.

Role of magnifying colonoscopy for diagnosis of colorectal neoplasms: From the perspective of Japanese colonoscopists

Colorectal cancer is the third leading cause of cancer-related death. As the therapeutic strategy for colorectal cancer depends on the clinical stage of the tumor, precise and accurate staging is necessary prior to treatment decision-making. Colonoscopy is an essential tool for detection and prevention of colorectal cancer, as it also allows for removal of adenomatous lesions. Using conventional endoscopy, however, it is sometimes difficult to differentiate neoplastic lesions from non-neoplastic lesions. Several new endoscopic technologies have been developed to provide a more precise diagnosis. Magnifying chromoendoscopy and narrow-band imaging endoscopy with or without magnification are invaluable not only for distinction of colorectal neoplastic lesions from non-neoplastic lesions, but also for the accurate diagnosis of invasion depth in colorectal cancers. Based on an accumulation of a large number of clinical data, the use of magnifying colonoscopy has become inevitable for the prediction of histology and the diagnosis of invasion depth of colorectal neoplasms in Japan.

Impact of reassessment of colonic hyperplastic polyps by expert GI pathologists

BACKGROUND

Recommended follow-up intervals after endoscopic removal of hyperplastic polyps (HP) and sessile serrated adenomas (SSA) differ because of assumed differences in biological behaviour. However, histopathologic differentiation is difficult, with higher SSA rates reported from specialist GI histopathologists.

OBJECTIVE

The objective of this study was to clarify the relevance of histologic reassessment of HP.

DESIGN AND SETTING

From a prospective screening colonoscopy study relevant serrated lesions (excluding distal small HP ≤5 mm) diagnosed by private practice pathologists were reassessed by four specialized GI pathologists

PATIENTS

One thousand sixty-nine screening colonoscopies were performed in patients.

MAIN OUTCOME MEASUREMENTS

In terms of main outcome measurements, there is a likelihood of changes of the HP diagnosis on reassessment, as well as interrater variability.

RESULTS

SSA were initially diagnosed in 7 cases (0.7%) and relevant HP in 83 (7.8%; 101 lesions). Of the latter, the chance of a change in diagnosis from HP to SSA by any of the four specialist histopathologists was higher for larger (>5 mm) and right-sided lesions (19.1 vs 1.3%, OR 18.4, p = 0.04) including a higher likelihood to change recommended follow-up intervals (32.1 vs 3.3%, p < 0.01). However, follow-up intervals were determined by concomitant adenomas in 41%. Interrater variability was also higher for these lesions (p = 0.04), with an overall kappa value of 0.48. However, this issue related to only 1.2% of the 1069 study cases.

LIMITATION

The limitations this study are the limited case number as well as limited retrospective assessment.

CONCLUSIONS

Right-sided HP >5 mm had a higher chance of change in diagnosis to SSA; therefore, they should probably be treated like adenomas and be removed. However, reliable data for recommendations on follow-up intervals of HP or SSA will require follow-up studies.

The "golden retriever" study: improving polyp retrieval rates by providing education and competitive feedback

BACKGROUND AND AIMS

Although optical diagnosis of small colorectal polyps can be achieved at expert centers, accurate prediction of histopathological outcomes has not been achieved in all practice settings. It is therefore important that resected polyps are retrieved for histology. The aims of this study were to evaluate the effect of education and competitive feedback on the overall polyp retrieval rate and to determine which polyp-related and procedure-related factors are associated with retrieval.

METHODS

We prospectively included consecutive colonoscopies performed at a single center between April 1, 2013 and April 1, 2014. Patients with inflammatory bowel disease or familial polyposis syndromes were excluded from analysis. Six months after the start of the study, all endoscopists were educated on the importance of polyp retrieval, and a competition was started by publicly providing feedback on the retrieval rate of all endoscopists and the monthly best 3 performers (or "golden retrievers") in particular. We compared overall retrieval rates in the 6 months before and after the start of the competition.

RESULTS

The overall polyp retrieval rate improved from 88% (525/594) to 93% (978/1047), comparing consecutive colonoscopies performed in the 6 months before and during the polyp retrieval competition (P < .01). The histopathological outcomes of retrieved polyps were not different before and during the competition. The retrieval rate of right-sided polyps increased from 85% to 95% during the competition (odds ratio [OR], 3.3; 95% confidence interval [CI], 2.0-5.4), whereas the left-sided retrieval rate remained 92%. On multivariable analysis, polyp size greater than 5 mm (OR, 4.1; 95% CI, 1.8-9.6) and in competition resection (OR, 1.8; 95% CI, 1.3-2.6) were significantly associated with polyp retrieval, respectively.

CONCLUSION

Providing education and competitive feedback to endoscopists will improve polyp retrieval rates, especially for clinically relevant, right-sided polyps.

Detection of Early Murine Colorectal Cancer by MMP-2/-9-Guided Fluorescence Endoscopy

BACKGROUND

Patients with ulcerative colitis are at increased risk for colorectal cancer and endoscopic surveillance is mandatory. Matrix metalloproteinases (MMPs)-2 and -9 activities are increased in malignant colonic mucosa. The aim of the study was to evaluate molecular imaging of MMP-2/-9 by fluorescence endoscopy (FE) for early tumor detection.

METHODS

Colorectal cancer in mice (n = 28) was induced by azoxymethane and dextran sodium sulfate. Twenty-four hours after intravenous injection of a nonpeptidic, Cy5.5-labeled MMP-selective tracer, tumor development was assessed in vivo by white light endoscopy and FE. Topical administration of the tracer was also investigated (after 5 minutes and 24 hours). Colonic tumors were evaluated ex vivo by fluorescence reflectance imaging, immunohistochemistry, Western blot analysis, and zymography.

RESULTS

Imaging of MMP-2/-9 expression by FE achieved a significantly higher contrast of the fluorescence signal in colonic adenomas compared with the adjacent nonmalignant mucosa (P < 0.001). Fluorescence reflectance imaging detected a significantly higher tracer uptake in adenoma compared with healthy mucosa (P < 0.001) and revealed a tumor size-dependent increase of tracer uptake (P < 0.01). Topical tracer administration did not facilitate tumor detection. Immunohistochemistry, Western blot analysis, and zymography indicated higher levels of MMP-2 and -9 in high-grade dysplasia and pT1 tumors ex vivo.

CONCLUSIONS

MMP-2/-9 expression was significantly increased in colorectal neoplasia. FE allows direct visualization of a prognostic parameter (here MMP-2/-9) on a molecular level and may improve the characterization of colorectal lesions and the adenoma detection rate in the future.

Management of Diminutive Colon Polyps Based on Endoluminal Imaging

Diminutive colon polyps, defined as 5 mm or less, are encountered increasingly at colonoscopy. The risk of serious pathology in such polyps is low. There is a risk and cost of resecting all such polyps and sending tissue for pathologic evaluation. Enhancement of endoluminal imaging may enable discrimination of neoplastic vs non-neoplastic polyps. If this discrimination can be performed accurately with high confidence, it may be possible to either resect and discard diminutive adenomas, or inspect and do-not-resect diminutive hyperplastic polyps. In 2011, an expert group recommended thresholds of 90% negative predictive value for adenomas, and 90% accuracy in predicting appropriate surveillance intervals. Since 2011, criteria for polyp discrimination have been published and validated by experts and nonexperts. In vivo studies have been performed to compare endoscopic impression and pathologic diagnosis. An expert panel was convened in late 2014 to review the literature to determine if the proposed thresholds for discrimination can be attained and to recommend the next steps for introducing changes in clinical practice. We conclude that threshold levels can be achieved with several endoscopic image enhancements. The next steps to implementation of practice change include acquiring data on training and competence, determining best practices for auditing performance, understanding patient education needs, and the potential cost benefit of such changes.

Real-time optical diagnosis for diminutive colorectal polyps using narrow-band imaging: the VALID randomised clinical trial

BACKGROUND

Diminutive (≤ 5 mm) colorectal polyps are common, and overwhelmingly benign. Routinely, after polypectomy, they are examined pathologically to determine the surveillance intervals. Advances in equipment and techniques, such as narrow-band imaging (NBI) colonoscopy, now permit reliable real-time optical diagnosis.

METHODS

We conducted a randomised single-masked study involving three institutions to determine whether optical diagnosis of diminutive colorectal polyps meets clinical practice standards and reduces the need for histopathology. We randomly assigned eligible patients undergoing routine high-definition colonoscopy to optical diagnosis using near focus versus standard view, using computer-generated block sequence. By validated criteria, we rendered an optical diagnosis and a confidence level (high vs low) for all polyps, using NBI. Our primary endpoint was the number of accurate high-confidence optical diagnoses compared with central blinded pathology in the two groups. We analysed data using intention to treat.

FINDINGS

We enrolled 558 subjects, and randomly assigned 281 to near focus and 277 to standard view optical diagnosis. We detected 1309 predominantly diminutive (74.5%) and neoplastic (60.0%) polyps. Endoscopists were significantly more likely, OR 2.2 (95% CI 1.6 to 3.0, p<0.0001), to make a high-confidence optical diagnosis with near focus (85.1%) than standard (72.6%) view. High-confidence diagnoses had 96.4% and 92.0% negative predictive value, respectively. Of all polyps, 75.3% (95% CI71.3% to 78.9%) had a high-confidence accurate prediction using near focus, compared with 63.1% (95% CI 58.5% to 67.6%) using standard view. Optical versus histopathological diagnosis showed excellent agreement between the surveillance intervals, 93.5% in near focus and 92.2% in standard view. The median diagnosis time was 14 s.

CONCLUSIONS

Real-time optical diagnosis using NBI colonoscopy may replace the pathology diagnosis for the majority of diminutive colorectal polyps. Using colonoscopy with near focus view increases the confidence level of the optical diagnosis. Optical diagnosis would be a paradigm shift in clinical practice of colonoscopy for colorectal cancer screening.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov Identifier: NCT01288833.

Epidemiology of Colorectal Adenomas and Histopathological Assessment of Endoscopic Specimens in the Colorectum

BACKGROUND

Colorectal cancer is one of the most frequently observed neoplasms in the world. It develops from intraepithelial neoplasia of the colorectal mucosa, and these precursor lesions are also known as adenoma. As the precursor lesion is known and can be detected easily, efficient screening strategies are available for a reliable prevention of colorectal adenocarcinoma, e.g. by colonoscopy.

METHODS

Literature databases (PubMed) were searched selectively for the keywords 'colorectal adenoma', 'epidemiology', and 'resection techniques'. The results are presented in the following text, also taking into account our own experience and the current S3 guidelines.

RESULTS

Endoscopic resection samples are one of the specimens most frequently assessed by pathologists. Therefore, gastroenterologists expect standardized and well-structured pathology reports, stating relevant information concerning the removed lesions and recommendations for clinical management. These aspects are summarized in the evidence-based S3 guideline.

CONCLUSION

As a consequence of colorectal adenoma resection during screening procedures, the carcinoma incidence is decreasing. For further advancements in successful prevention, knowledge of different precursor lesions (conventional adenoma, serrated adenoma) is important, but also structured communication between the different disciplines engaged in colorectal cancer screening.

ASGE Technology Committee systematic review and meta-analysis assessing the ASGE PIVI thresholds for adopting real-time endoscopic assessment of the histology of diminutive colorectal polyps

In vivo real-time assessment of the histology of diminutive (≤5 mm) colorectal polyps detected at colonoscopy can be achieved by means of an "optical biopsy" by using currently available endoscopic technologies. This systematic review and meta-analysis was performed by the American Society for Gastrointestinal Endoscopy (ASGE) Technology Committee to specifically assess whether acceptable performance thresholds outlined by an ASGE Preservation and Incorporation of Valuable endoscopic Innovations (PIVI) document for clinical adoption of these technologies have been met. We conducted direct meta-analyses calculating the pooled negative predictive value (NPV) for narrow-band imaging (NBI), i-SCAN, and Fujinon Intelligent Color Enhancement (FICE)-assisted optical biopsy for predicting adenomatous polyp histology of small/diminutive colorectal polyps. We also calculated the pooled percentage agreement with histopathology when assigning postpolypectomy surveillance intervals based on combining real-time optical biopsy of colorectal polyps 5 mm or smaller with histopathologic assessment of polyps larger than 5 mm. Random-effects meta-analysis models were used. Statistical heterogeneity was evaluated by means of I(2) statistics. Our meta-analyses indicate that optical biopsy with NBI, exceeds the NPV threshold for adenomatous polyp histology, supporting a "diagnose-and-leave" strategy for diminutive predicted nonneoplastic polyps in the rectosigmoid colon. The pooled NPV of NBI for adenomatous polyp histology by using the random-effects model was 91% (95% confidence interval [CI], 88-94). This finding was associated with a high degree of heterogeneity (I(2) = 89%). Subgroup analysis indicated that the pooled NPV was greater than 90% for academic medical centers (91.8%; 95% CI, 89-94), for experts (93%; 95% CI, 91-96), and when the optical biopsy assessment was made with high confidence (93%; 95% CI, 90-96). Our meta-analyses also indicate that the agreement in assignment of postpolypectomy surveillance intervals based on optical biopsy with NBI of diminutive colorectal polyps is 90% or greater in academic settings (91%; 95% CI, 86-95), with experienced endoscopists (92%; 95% CI, 88-96) and when optical biopsy assessments are made with high confidence (91%; 95% CI, 88-95). Our systematic review and meta-analysis confirms that the thresholds established by the ASGE PIVI for real-time endoscopic assessment of the histology of diminutive polyps have been met, at least with NBI optical biopsy, with endoscopists who are expert in using this advanced imaging technology and when assessments are made with high confidence.

Endoscopic histological assessment of colonic polyps by using elastic scattering spectroscopy

BACKGROUND

Elastic-scattering spectroscopy (ESS) can assess in vivo and in real-time the scattering and absorption properties of tissue related to underlying pathologies.

OBJECTIVES

To evaluate the potential of ESS for differentiating neoplastic from non-neoplastic polyps during colonoscopy.

DESIGN

Pilot study, retrospective data analysis.

SETTING

Academic practice.

PATIENTS

A total of 83 patients undergoing screening/surveillance colonoscopy.

INTERVENTIONS

ESS spectra of 218 polyps (133 non-neoplastic, 85 neoplastic) were acquired during colonoscopy. Spectral data were correlated with the classification of biopsy samples by 3 GI pathologists. High-dimensional methods were used to design diagnostic algorithms.

MAIN OUTCOME MEASUREMENTS

Diagnostic performance of ESS.

RESULTS

Analysis of spectra from polyps of all sizes (N = 218) resulted in a sensitivity of 91.5%, specificity of 92.2%, and accuracy of 91.9% with a high-confidence rate of 90.4%. Restricting analysis to polyps smaller than 1 cm (n = 179) resulted in a sensitivity of 87.0%, specificity of 92.1%, and accuracy of 90.6% with a high-confidence rate of 89.3%. Analysis of polyps 5 mm or smaller (n = 157) resulted in a sensitivity of 86.8%, specificity of 91.2%, and accuracy of 90.1% with a high-confidence rate of 89.8%.

LIMITATIONS

Sample size, retrospective validation used to obtain performance estimates.

CONCLUSION

Results indicate that ESS permits accurate, real-time classification of polyps as neoplastic or non-neoplastic. ESS is a simple, low cost, clinically robust method with minimal impact on procedure flow, especially when integrated into standard endoscopic biopsy tools. Performance on polyps 5 mm or smaller indicates that ESS may, in theory, achieve Preservation and Incorporation of Valuable Endoscopic Innovations performance thresholds. ESS may one day prove to be a useful tool used in endoscopic screening and surveillance of colorectal cancer.