High-definition endoscopy with i-Scan for evaluation of small colon polyps: the HiSCOPE study

Mucosal imaging in colon polyps: New advances and what the future may hold

An expanding range of advanced mucosal imaging technologies have been developed with the goal of improving the detection and characterization of lesions in the gastrointestinal tract. Many technologies have targeted colorectal neoplasia given the potential for intervention prior to the development of invasive cancer in the setting of widespread surveillance programs. Improvement in adenoma detection reduces miss rates and prevents interval cancer development. Advanced imaging technologies aim to enhance detection without significantly increasing procedural time. Accurate polyp characterisation guides resection techniques for larger polyps, as well as providing the platform for the “resect and discard” and “do not resect” strategies for small and diminutive polyps. This review aims to collate and summarise the evidence regarding these technologies to guide colonoscopic practice in both interventional and non-interventional endoscopists.

Electronic chromo-endoscopy: technical details and a clinical perspective

Precise endoscopic assessment is necessary to detect neoplastic changes in an early stage. Electronic or virtual chromo-endoscopy (ECE) is an alternative to conventional dye-based chromo-endoscopy which markedly improves capillary pattern and hence can detect micro-vessel morphological changes of early neoplasia to target biopsies and aid in diagnosis. The clinical significance increased after the advent of endoscopic treatment modalities like ESD/EMR which requires precise delineation of extent and depth of lesion. Most of the studies have used narrow-band imaging (NBI) (Olympus Medical Systems Tokyo, Japan), although data from i-SCAN (PENTAX Endoscopy, Tokyo, Japan) and flexible spectral imaging color enhancement (FICE) (Fujinon, Fujifilm Medical Co, Saitama, Japan) are emerging. Electronic chromo-endoscopy is convenient compared to dye-based chromo-endoscopy in the sense that it is available at the push of a button in endoscope and reduces procedure time substantially with comparable efficacy. Scope of this review is to discuss available electronic chromo-endoscopy modalities and their role in the diagnosis, surveillance, and management of early GI neoplasia.

Clinical validation of the SIMPLE classification for optical diagnosis of colorectal polyps

Background and study aims  A novel endoscopic optical diagnosis classification system (SIMPLE) has recently been developed. This study aimed to evaluate the SIMPLE classification in a clinical cohort. Patients and methods  All diminutive and small colorectal polyps found in a cohort of individuals undergoing screening, diagnostic, or surveillance colonoscopies underwent optical diagnosis using image-enhanced endoscopy (IEE) and the SIMPLE classification. The primary outcome was the agreement of surveillance intervals determined by optical diagnosis compared with pathology-based results for diminutive polyps. Secondary outcomes included the negative predictive value (NPV) for rectosigmoid adenomas, the percentage of pathology exams avoided, and the percentage of immediate surveillance interval recommendations. Analysis of optical diagnosis for polyps ≤ 10 mm was also performed. Results  399 patients (median age 62.6 years; 55.6 % female) were enrolled. For patients with at least one polyp ≤ 5 mm undergoing optical diagnosis, agreement with pathology-based surveillance intervals was 93.5 % (95 % confidence interval [CI] 91.4-95.6). The NPV for rectosigmoid adenomas was 86.7 % (95 %CI 77.5-93.2). When using optical diagnosis, pathology analysis could be avoided in 61.5 % (95 %CI 56.9-66.2) of diminutive polyps, and post-colonoscopy surveillance intervals could be given immediately to 70.9 % (95 %CI 66.5-75.4) of patients. For patients with at least one ≤ 10 mm polyp, agreement with pathology-based surveillance intervals was 92.7 % (95 %CI 89.7-95.1). NPV for rectosigmoid adenomas ≤ 10 mm was 85.1 % (95 %CI CI 76.3-91.6). Conclusions  IEE with the SIMPLE classification achieved the quality benchmark for the resect and discard strategy; however, the NPV for rectosigmoid polyps requires improvement.

Medical needs related to the endoscopic technology and colonoscopy for colorectal cancer diagnosis

Background

The high incidence and mortality rate of colorectal cancer require new technologies to improve its early diagnosis. This study aims at extracting the medical needs related to the endoscopic technology and the colonoscopy procedure currently used for colorectal cancer diagnosis, essential for designing these demanded technologies.

Methods

Semi-structured interviews and an online survey were used.

Results

Six endoscopists were interviewed and 103 were surveyed, obtaining the demanded needs that can be divided into: a) clinical needs, for better polyp detection and classification (especially flat polyps), location, size, margins and penetration depth; b) computer-aided diagnosis (CAD) system needs, for additional visual information supporting polyp characterization and diagnosis; and c) operational/physical needs, related to limitations of image quality, colon lighting, flexibility of the endoscope tip, and even poor bowel preparation.

Conclusions

This study shows some undertaken initiatives to meet the detected medical needs and challenges to be solved. The great potential of advanced optical technologies suggests their use for a better polyp detection and classification since they provide additional functional and structural information than the currently used image enhancement technologies. The inspection of remaining tissue of diminutive polyps (< 5 mm) should be addressed to reduce recurrence rates. Few progresses have been made in estimating the infiltration depth. Detection and classification methods should be combined into one CAD system, providing visual aids over polyps for detection and displaying a Kudo-based diagnosis suggestion to assist the endoscopist on real-time decision making. Estimated size and location of polyps should also be provided. Endoscopes with 360° vision are still a challenge not met by the mechanical and optical systems developed to improve the colon inspection. Patients and healthcare providers should be trained to improve the patient’s bowel preparation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08190-z.

Will purposely seeking detect more colorectal polyps than routine performing during colonoscopy?

BACKGROUND & GOALS

We observed that the number of colorectal polyps found intraoperatively was often higher than that encountered preoperatively during elective colonoscopic polypectomy. To evaluate whether more polyps can be detected when they are purposely sought than when they are routinely examined during colonoscopy.

MATERIALS AND METHODS

Patients undergoing colonoscopy were randomized into groups A and B. Before colonoscopy was performed, endoscopists were instructed to seek polyps for group A purposely but not for group B. Polypectomy was electively completed. In groups A and B, the cases of elective polypectomy were named groups AR and BR, including groups AR-1 and BR-1, during the first colonoscopy and groups AR-2 and BR-2 during the second colonoscopy for polypectomy, respectively. The following data were calculated: the number of polyps detected (NPD) and the polyp detection rate (PDR) in all cases and the number of polyps missed (NPM) and partial polyp miss rate (PPMR) in the cases of colorectal polyps.

RESULTS

A total of 419 cases were included in group A, 421 in group B, 43 in group AR, and 35 in group BR. No significant differences in PDR were found between groups A and B and in PPMR between groups AR-1 and BR-1 (P > .05), although PPMR in group AR-1 was higher than in group AR-2 (P < .05), similar results were found in PPMR between groups BR-1 and BR-2 (P < .05).

CONCLUSION

Purposely seeking for colorectal polyps did not result in more polyps detected compared with routine colonoscopy.

The quality of colorectal polypectomy. Is it enough to have just a visual assessment of the site?

INTRODUCTION

Performing a colonoscopy allows the examination of the entire colon and the assessment of polyps.

PATIENTS, MATERIALS AND METHODS

We performed a retrospective analysis of prospectively collected data from January 2018 until February 2020 (two years), in which we enrolled a number of 210 patients performing colonoscopy in the Research Center of Gastroenterology and Hepatology, University of Medicine and Pharmacy of Craiova, Romania. We performed 326 polypectomies.

RESULTS

We classified the polyps into diminutive (n=169), small (n=103) and large polyps (n=54). Regarding the polypectomy technique, our results indicated that 40 out of 48 (83.3%) polypectomies with the biopsy forceps were complete, as well as 27 out of 31 (87.1%) cold snare polypectomies and 12 out of 14 (85.7%) hot snare polypectomies. The differences were not statistically significant (p=0.116). Regarding the number of incomplete polypectomies, our data suggests that the high expertise endoscopist had two incomplete resections (5.1% of total), the medium expertise endoscopist 1 had also two incomplete resections (11.1% of total), the medium expertise endoscopist 2 had three incomplete resections (15% of total), the limited expertise endoscopist 1 had three incomplete resections (27.27% of total) and the limited expertise endoscopist 2 had four incomplete resections (30.76% of total). Analyzing the data, the differences were statistically significant (p=0.006).

CONCLUSIONS

Our study is able to suggest that high-definition white-light endoscopy (HD-WLE) macroscopic visualization of the polyp resection site is not enough to assess complete polyp resection and follow-up colonoscopy should be performed for cases with incomplete margins of resection.

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.

Advanced Endoscopic Imaging in Colonic Neoplasia

Background

Endoscopic imaging is a rapidly evolving field with a constant influx of new concepts and technologies. Since the introduction of video endoscopy and subsequently high-definition imaging as the first revolutions in gastrointestinal endoscopy, several technologies of virtual chromoendoscopy have been developed and brought to the market in the past decade, which have shaped and revolutionized for a second time our approach to endoscopic imaging. In parallel to these developments, microscopic imaging technologies, such as endomicroscopy and endocytoscopy, allow us to examine single cells within the mucosa in real time, thereby enabling histological diagnoses during ongoing endoscopy.

Summary

In this review, we provide an overview on the technical background of different technologies of advanced endoscopic imaging, and then review and discuss their role and applications for the diagnosis and management of colorectal neoplasms as well as limitations and challenges that exist despite all technological improvements.

Key Messages

Technologies of advanced endoscopic imaging have profound impact not only on our imaging capabilities, they are also about to fundamentally change our approach to managing lesions in the gastrointestinal tract: not every lesion found during colonoscopy has to be excised or sent for histopathologic evaluation. However, before this becomes widespread reality, major obstacles such as patient acceptance, adoption by less trained endoscopists, and also legal aspects need to carefully addressed. The development of computer-aided diagnosis and artificial intelligence algorithms hold the potential to overcome the obstacles associated with the concept of optical biopsy and will most likely fundamentally facilitate, shape, and change decision making in the management of colorectal lesions.

Effect of video monitor size on polyp detection: a prospective, randomized, controlled trial

BACKGROUND AND AIMS

The adenoma detection rate (ADR) is the most important quality metric for colonoscopy. Numerous factors are known to influence ADR. However, no data on the effect of monitor size on ADR exist. The aim of this study was to compare the ADR and polyp detection rate (PDR) achieved using 2 different-size video monitors (19-inch diagonal and 32-inch diagonal).

METHODS

In a single-center, prospective, randomized clinical trial, endoscopists were randomized on a daily basis to perform routine ambulatory colonoscopies with either a 32-inch diagonal or a 19-inch diagonal video monitor.

RESULTS

The study was conducted between October 2013 and April 2014 in an outpatient center of a tertiary referral hospital. Fifteen endoscopists performed 1795 outpatient colonoscopies (mean age, 55 years; 56% women; screening, 56%). There was no substantial difference in baseline patient characteristics between the 2 arms. The overall ADR (27.4% vs 27.9%; P = .80) and PDR (32.8% vs 34.4%; P = .50) were not significantly different between the 32-inch and 19-inch monitor group, respectively. The findings were not significantly altered when stratified by indication, cecal intubation, bowel preparation, operator experience, and time of endoscopy as well as in a multivariable model that included these variables as potential confounders (all P > .05). Overall, the ADR and PDR for each individual endoscopist did not appear to be influenced by monitor size.

CONCLUSIONS

The results of this trial do not support the notion that larger video monitors improve ADR. Future efforts to increase ADR should focus on other aspects of colonoscopy. (Clinical trial registration number: NCT01952418.).

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.

Standards of diagnostic colonoscopy for early-stage neoplasia: Recommendations by an Asian private group

BACKGROUND AND AIM

In recent years, the incidence of colorectal cancer has been increasing, and it is now becoming the major cause of cancer death in Asian countries. The aim of the present study was to develop Asian expert-based consensus to standardize the preparation, detection and characterization for the diagnosis of early-stage colorectal neoplasia.

METHODS

A professional group was formed by 36 experts of the Asian Novel Bio-Imaging and Intervention Group (ANBI² G) members. Representatives from 12 Asia-Pacific countries participated in the meeting. The group organized three consensus meetings focusing on diagnostic endoscopy for gastrointestinal neoplasia. The Delphi method was used to develop the consensus statements.

RESULTS

Through the three consensus meetings with debating, reviewing the literature and regional data, a consensus was reached at third meeting in 2016. The consensus was reached on a total of 10 statements. Summary of statements is as follows: (i) Adequate bowel preparation for high-quality colonoscopy; (ii) Antispasmodic agents for lesion detection; (iii) Image-enhanced endoscopy (IEE) for polyp detection; (iv) Adenoma detection rate for quality indicators; (v) Good documentation of colonoscopy findings; (vi) Complication rates; (vii) Cecal intubation rate; (viii) Cap-assisted colonoscopy (CAC) for polyp detection; (ix) Macroscopic classification using indigocarmine spray for characterization of colorectal lesions; and (x) IEE and/or magnifying endoscopy for prediction of histology.

CONCLUSION

This consensus provides guidance for carrying out endoscopic diagnosis and characterization for early-stage colorectal neoplasia based on the evidence. This will enhance the quality of endoscopic diagnosis and improve detection of early-stage colorectal neoplasia.

A roadmap for the clinical implementation of optical-imaging biomarkers

Clinical workflows for the non-invasive detection and characterization of disease states could benefit from optical-imaging biomarkers. In this Perspective, we discuss opportunities and challenges towards the clinical implementation of optical-imaging biomarkers for the early detection of cancer by analysing two case studies: the assessment of skin lesions in primary care, and the surveillance of patients with Barrett's oesophagus in specialist care. We stress the importance of technical and biological validations and clinical-utility assessments, and the need to address implementation bottlenecks. In addition, we define a translational roadmap for the widespread clinical implementation of optical-imaging technologies.

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.

Virtual Chromoendoscopy With FICE for the Classification of Polypoid and Nonpolypoid Raised Lesions in Ulcerative Colitis

GOALS

The aim of this study was to analyze the performance of Fuji Intelligent Color Enhancement (FICE) using the classification of Kudo in the differentiation of neoplastic and non-neoplastic raised lesions in ulcerative colitis (UC).

BACKGROUND

The Kudo classification of mucosal pit patterns is an aid for the differential diagnosis of colorectal polyps in the general population, but no systematic studies are available for all forms of raised lesions in UC.

STUDY

All raised, polypoid and nonpolypoid, lesions found during consecutive surveillance colonoscopies with FICE for long-standing UC were included. In the primary prospective analysis, the Kudo classification was used to predict the histology by FICE. In a post hoc analysis, further endoscopic markers were also explored.

RESULTS

Two hundred and five lesions (mean size, 8 mm; range, 2 to 30 mm) from 59 patients (mean age, 56 y; range, 21 to 79 y) were analyzed. Twenty-three neoplastic (11%), 18 hyperplastic (9%), and 164 inflammatory (80%) lesions were found. Thirty-one lesions (15%), none of which were neoplastic, were unclassifiable according to Kudo. After logistic regression, a strong negative association resulted between endoscopic activity and neoplasia, whereas the presence of a fibrin cap was significantly associated with endoscopic activity. Using FICE, the sensitivity, specificity, and positive and negative likelihood ratios of the Kudo classification were 91%, 76%, 3.8, and 0.12, respectively. The corresponding values by adding the fibrin cap as a marker of inflammation were 91%, 93%, 13, and 0.10, respectively.

CONCLUSIONS

FICE can help to predict the histology of raised lesions in UC. A new classification of pit patterns, based on inflammatory markers, should be developed in the setting of UC to improve the diagnostic performance.

Blue-light imaging compared with high-definition white light for real-time histology prediction of colorectal polyps less than 1 centimeter: a prospective randomized study

BACKGROUND AND AIMS

Blue-light imaging (BLI) is a new chromoendoscopy technique, potentially useful for differentiating neoplastic from nonneoplastic lesions. The present study was aimed at comparing BLI with high-definition white light (HDWL) in the real-time histology prediction of colon polyps <10 mm.

METHODS

Consecutive outpatients undergoing colonoscopy with the ELUXEO 7000 endoscopy platform and 760 series video colonoscopes (Fujifilm Co, Tokyo, Japan) who had at least 1 polyp <10 mm were randomized to BLI or HDWL for polyp characterization. The accuracy of high-confidence real-time histology prediction (adenoma vs not adenoma) by either BLI or HDWL for polyps <10 mm (primary end-point) and diminutive (≤5 mm) polyps was calculated, along with sensitivity, specificity, and positive and negative predictive values, with histopathology as the reference standard.

RESULTS

A total of 483 polyps were detected in 245 randomized patients (125 and 120 in the BLI and HDWL arms, respectively). A total of 358 were diminutive, and 283 were adenomas. Overall, 222 (85.7%) and 193 (86.1%) polyps were characterized with high confidence by BLI and HDWL, respectively (P = .887), with an overall accuracy of 92% and 84%, respectively (P = .011). The accuracy was significantly higher by BLI than HDWL, also for diminutive polyps (92% vs 83%; P = .008). When BLI was used, the negative predictive value for diminutive rectosigmoid polyps was 88%, and the post-polypectomy surveillance interval was correctly attributed in 85.7% and 93.7% of patients, respectively, according to U.S. and European guidelines.

CONCLUSION

BLI was superior to HDWL for the real-time prediction of histology in polyps <10 mm. A BLI-dedicated classification might further improve the endoscopist performance. (Clinical trial registration number: NCT03274115.).

Optical Diagnosis of Colorectal Polyps: Recent Developments

PURPOSE OF REVIEW

Optical diagnosis of diminutive colorectal polyps has been recently proposed as an alternative to histopathologic diagnosis. Recent developments in imaging techniques, new classification systems, and the use of artificial intelligence have allowed for increased viability of optical diagnosis. This review provides an up-to-date overview of optical diagnosis recommendations, classifications, outcomes, and recent developments.

RECENT FINDINGS

There are currently seven major classification systems and three major society recommendations for quality benchmarks for optical diagnosis of diminutive polyps. The NICE classification has been extensively studied and meets quality benchmarks for most imaging techniques but does not allow for the diagnosis of sessile serrated polyps (SSPs). The SIMPLE classification has met quality benchmarks for NBI and i-Scan and allows for the diagnosis of SSPs. Other classification systems need to be further studied to validate effectiveness. Computer-assisted diagnosis of colorectal polyps is a very promising recent development with first studies showing that society-recommended quality benchmarks for real-time colonoscopies on patients are being met. Limitations include a non-negligible percentage of failure to diagnose, low specificity, and low number of real-time diagnostic studies. More research needs to be performed to further understand the value of artificial intelligence for optical polyp diagnosis. Optical diagnosis of diminutive colorectal polyps is currently a viable strategy for experienced endoscopists using validated classifications and imaging-enhanced endoscopy. Artificial intelligence-based diagnosis could make optical diagnosis widely applicable but is currently in its early developmental stage.

Virtual chromoendoscopy for the real-time assessment of colorectal polyps in vivo: a systematic review and economic evaluation

BACKGROUND

Current clinical practice is to remove a colorectal polyp detected during colonoscopy and determine whether it is an adenoma or hyperplastic by histopathology. Identifying adenomas is important because they may eventually become cancerous if untreated, whereas hyperplastic polyps do not usually develop into cancer, and a surveillance interval is set based on the number and size of adenomas found. Virtual chromoendoscopy (VCE) (an electronic endoscopic imaging technique) could be used by the endoscopist under strictly controlled conditions for real-time optical diagnosis of diminutive (≤ 5 mm) colorectal polyps to replace histopathological diagnosis.

OBJECTIVE

To assess the clinical effectiveness and cost-effectiveness of the VCE technologies narrow-band imaging (NBI), flexible spectral imaging colour enhancement (FICE) and i-scan for the characterisation and management of diminutive (≤ 5 mm) colorectal polyps using high-definition (HD) systems without magnification.

DESIGN

Systematic review and economic analysis.

PARTICIPANTS

People undergoing colonoscopy for screening or surveillance or to investigate symptoms suggestive of colorectal cancer.

INTERVENTIONS

NBI, FICE and i-scan.

MAIN OUTCOME MEASURES

Diagnostic accuracy, recommended surveillance intervals, health-related quality of life (HRQoL), adverse effects, incidence of colorectal cancer, mortality and cost-effectiveness of VCE compared with histopathology.

DATA SOURCES

Electronic bibliographic databases including MEDLINE, EMBASE, The Cochrane Library and Database of Abstracts of Reviews of Effects were searched for published English-language studies from inception to June 2016. Bibliographies of related papers, systematic reviews and company information were screened and experts were contacted to identify additional evidence.

REVIEW METHODS

Systematic reviews of test accuracy and economic evaluations were undertaken in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. Meta-analyses were conducted, where possible, to inform the independent economic model. A cost-utility decision-analytic model was developed to estimate the cost-effectiveness of VCE compared with histopathology. The model used a decision tree for patients undergoing endoscopy, combined with estimates of long-term outcomes (e.g. incidence of colorectal cancer and subsequent morbidity and mortality) derived from University of Sheffield School of Health and Related Research's bowel cancer screening model. The model took a NHS perspective, with costs and benefits discounted at 3.5% over a lifetime horizon. There were limitations in the data on the distribution of adenomas across risk categories and recurrence rates post polypectomy.

RESULTS

Thirty test accuracy studies were included: 24 for NBI, five for i-scan and three for FICE (two studies assessed two interventions). Polyp assessments made with high confidence were associated with higher sensitivity and endoscopists experienced in VCE achieved better results than those without experience. Two economic evaluations were included. NBI, i-scan and FICE are cost-saving strategies compared with histopathology and the number of quality-adjusted life-years gained was similar for histopathology and VCE. The correct surveillance interval would be given to 95% of patients with NBI, 94% of patients with FICE and 97% of patients with i-scan.

LIMITATIONS

Limited evidence was available for i-scan and FICE and there was heterogeneity among the NBI studies. There is a lack of data on longer-term health outcomes of patients undergoing VCE for assessment of diminutive colorectal polyps.

CONCLUSIONS

VCE technologies, using HD systems without magnification, could potentially be used for the real-time assessment of diminutive colorectal polyps, if endoscopists have adequate experience and training.

FUTURE WORK

Future research priorities include head-to-head randomised controlled trials of all three VCE technologies; more research on the diagnostic accuracy of FICE and i-scan (when used without magnification); further studies evaluating the impact of endoscopist experience and training on outcomes; studies measuring adverse effects, HRQoL and anxiety; and longitudinal data on colorectal cancer incidence, HRQoL and mortality.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42016037767.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

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).

Leaving colorectal polyps in place can be achieved with high accuracy using blue light imaging (BLI)

Objectives

A negative predictive value of more than 90% is proposed by the American Society of Gastrointestinal Endoscopy Preservation and Incorporation of Valuable Endoscopic Innovations (PIVI) statement for a new technology in order to leave distal diminutive colorectal polyps in place without resection. To our knowledge, no prior prospective study has yet evaluated the feasibility of the most recently introduced blue light imaging (BLI) system for real-time endoscopic prediction of polyp histology for the specific endpoint of leaving hyperplastic polyps in place.

Aims

Prospective assessment of real-time prediction of colorectal polyps by using BLI.

Material and methods

In total, 177 consecutive patients undergoing screening or surveillance colonoscopy were included. Colorectal polyps were evaluated in real-time by using high-definition endoscopy and the BLI technology without optical magnification. Before resection, the endoscopist described each polyp according to size, shape and surface characteristics (pit and vascular pattern, colour and depression), and histology was predicted with a level of confidence (high or low).

Results

Histology was predicted with high confidence in 92.5% of polyps. Sensitivity of BLI for prediction of adenomatous histology was 92.68%, with a specificity and accuracy of 94.87 and 93.75%, respectively. Following the recommendation of the PIVI statement, positive and negative predictive values were calculated with values of 95 and 92.5%, respectively. Prediction of surveillance based on both US and European guidelines was correctly predicted in 91% of patients.

Conclusion

The most recently introduced BLI technology is accurate enough to leave distal colorectal polyps in place without resection. BLI also allowed for assignment of postpolypectomy surveillance intervals. This approach therefore has the potential to reduce costs and risks associated with the redundant removal of diminutive colorectal polyps.

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.

Early detection of ulcerative colitis-associated colorectal cancer

Colitis-associated colorectal cancer (CACC) is one of the most serious complications of inflammatory bowel disease (IBD), particularly in ulcerative colitis (UC); it accounts for approximately 15% of all-causes mortality among IBD patients. Because CACC shows a worse prognosis and higher mortality than sporadic colorectal cancer, early detection is critical. Colonoscopy is primarily recommended for surveillance and several advanced endoscopic imaging techniques are emerging. In addition, recent studies have reported on attempts to develop clinically relevant biomarkers for surveillance using various biosamples, which may become high-performance screening tools in the future, so the best approach and technique for cancer surveillance in long-standing UC patients remain under debate. This review gives a comprehensive description and summary about what progress has been made in terms of early CACC detection.

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.

Can technology increase adenoma detection rate?

Colorectal cancer is the third most common cancer worldwide and the second most common cause of cancer-related death in Europe and North America. Colonoscopy is the gold standard investigation for the colon but is not perfect, and small or flat adenomas can be missed which increases the risk of patients subsequently developing colorectal cancer. Adenoma detection rate is the most widely used marker of quality, and low rates are associated with increased rates of post-colonoscopy colorectal cancer. Standards of colonoscopy and adenoma detection vary widely between different endoscopists. Interventions to improve adenoma detection rate are therefore required. Many devices have been purported to increase adenoma detection rate. This review looks at current available evidence for device technology to improve adenoma detection rate during colonoscopy.

High-definition i-Scan colonoscopy is superior in the detection of diminutive polyps compared with high-definition white light colonoscopy: a prospective randomized-controlled trial

INTRODUCTION

Recognition of flat and small neoplastic lesions by colonoscopy is still challenging. High-definition (HD) i-Scan colonoscopy is a promising technique to maximize the sensitivity of colonoscopy; however, whether i-Scan can increase the detection rate of polyps is still unclear. The aim of this study was to prospectively compare HD i-Scan colonoscopy with HD colonoscopy for the detection rate of polyps in routine practice.

MATERIALS AND METHODS

A total of 449 patients who underwent total colonoscopy for the first time were randomized in a 1 : 1 ratio to undergo HD+i-Scan colonoscopy or HD colonoscopy. Detected colorectal polyps were judged according to type, location, and size. The primary endpoint was the detection rate and the total number of polyps.

RESULTS

The number of polyps identified in the HD+i-Scan group was significantly higher than that in the HD group (P=0.041), and this difference was more obvious for diminutive polyps (P=0.035). The number of patients with at least one polyp was not significantly different between the two groups irrespective of the size or the location. Overall, 268 polyps were removed, 130 in the HD+i-Scan group and 138 in the HD group. Among these, three high-grade intraepithelial neoplasia were found in diminutive polyps.

CONCLUSION

HD+i-Scan colonoscopy is superior to HD colonoscopy in detecting diminutive polyps on the basis of this prospective randomized-controlled trial.

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.

Digital chromoendoscopy utilization in clinical practice: A survey of gastroenterologists in Connecticut

AIM: To use a survey to characterize and identify potential barriers to the use of digital chromoendoscopy (DC) by practicing gastroenterologists.

METHODS: An anonymous, internet-based survey was sent to gastroenterologists in Connecticut who were members of one of three national gastrointestinal organizations. The survey collected demographic information, frequency of DC use, types of procedures that the respondent performs, setting of practice (academic vs community), years out of training, amount of training in DC, desire to have DC training and perceived barriers to DC use. Responses were collected anonymously. The primary endpoint was the proportion of endoscopists utilizing DC. Associations between the various data collected were analyzed using χ² test.

RESULTS: One hundred and twenty-four gastroenterologists (48%) of 261 who received the online survey responded. Seventy-eight percent of surveyed gastroenterologists have used DC during the performance of upper endoscopy and 81% with lower endoscopy. DC was used in more than half of procedures by only 14% of gastroenterologists during upper endoscopy and 12% during lower endoscopy. Twenty-three percent (upper) and 21% (lower) used DC more than one quarter of the time. DC was used for 10% or less of endoscopies by 60% (upper) and 53% (lower) of respondents. Endoscopists reported lack of training as the leading deterrent to DC use with 36% reporting it as their primary deterrent. Eighty-nine percent of endoscopists never received formal training in DC. Lack of time (30% of respondents), lack of evidence (24%) and lack of reimbursement (10%) were additional deterrents. There were no differences in DC use relative to academic vs community practice setting or years out of training.

CONCLUSION: DC is used infrequently by most endoscopists, primarily due to a lack of training. Training opportunities should be expanded to meet the interest expressed by the majority of endoscopists.

The diminutive colon polyp: biopsy, snare, leave alone?

PURPOSE OF REVIEW

Diminutive polyps, measuring between 1 and 5 mm, represent the vast majority of colorectal polyps encountered during screening colonoscopy. Although the chance of harboring advanced adenoma or neoplastic cells is low, ensuring a complete polyp resection with clear margins is crucial to reduce the risk of interval colorectal cancer. The purpose of this review was to evaluate the different methods applied for polypectomy of diminutive polyps and clarify whether a diminutive polyp should be retrieved or left in place.

RECENT FINDINGS

Cold biopsy polypectomy is indicated for resection of polyps measuring 1-3 mm and removal of 4-5 mm polyps should be ensured by cold snare polypectomy. Over the last decade, hot biopsy polypectomy has been gradually abandoned because of an increased risk of diathermic injury. The resect and discard strategy and the diagnose and disregard strategy should be performed only by expert endoscopists, who should use validated scales and document the polyp features by storing several endoscopic images.

SUMMARY

Nowadays, complete resection of diminutive polyps, following the most appropriate technique, is recommended in clinical practice. The resect and discard strategy and the diagnose and disregard strategy should be reserved to expert endoscopists.

High-definition endoscopy with digital chromoendoscopy for histologic prediction of distal colorectal polyps

Background

Distal diminutive colorectal polyps are common and accurate endoscopic prediction of hyperplastic or adenomatous polyp histology could reduce procedural time, costs and potential risks associated with the resection. Within this study we assessed whether digital chromoendoscopy can accurately predict the histology of distal diminutive colorectal polyps according to the ASGE PIVI statement.

Methods

In this prospective cohort study, 224 consecutive patients undergoing screening or surveillance colonoscopy were included. Real time histology of 121 diminutive distal colorectal polyps was evaluated using high-definition endoscopy with digital chromoendoscopy and the accuracy of predicting histology with digital chromoendoscopy was assessed.

Results

The overall accuracy of digital chromoendoscopy for prediction of adenomatous polyp histology was 90.1 %. Sensitivity, specificity, positive and negative predictive values were 93.3, 88.7, 88.7, and 93.2 %, respectively. In high-confidence predictions, the accuracy increased to 96.3 % while sensitivity, specificity, positive and negative predictive values were calculated as 98.1, 94.4, 94.5, and 98.1 %, respectively. Surveillance intervals with digital chromoendoscopy were correctly predicted with >90 % accuracy.

Conclusions

High-definition endoscopy in combination with digital chromoendoscopy allowed real-time in vivo prediction of distal colorectal polyp histology and is accurate enough to leave distal colorectal polyps in place without resection or to resect and discard them without pathologic assessment. This approach has the potential to reduce costs and risks associated with the redundant removal of diminutive colorectal polyps.

Trial registration

ClinicalTrials NCT02217449.

Image-enhanced endoscopy technology in the gastrointestinal tract: what is available?

Gastrointestinal malignancy accounts for approximately a fifth of all cancer deaths in the United Kingdom. By the time patients are symptomatic, lesions are often advanced, with limited treatment options available. The development of effective endoscopic therapies means that neoplastic lesions can now be treated with improved patient outcomes. This has led to a paradigm shift, whereby the aim of digestive endoscopy is to identify premalignant conditions or early neoplastic change, in order to make an impact on their natural history. This has necessitated an improvement in imaging techniques in order to identify subtle mucosal changes that may harbour precancerous cells. At present there is an array of available imaging modalities, each with implications on cost, training and lesion detection. Here we describe the scientific rationale behind the major commercially available techniques as well as offering a glimpse at possible future directions.

Optical diagnosis of small colorectal polyps during colonoscopy: when to resect and discard?

Colonoscopy with polypectomy has been shown to be effective in reducing incidence and mortality from colorectal cancer (CRC). The increase in use of colonoscopy in national bowel cancer screening programmes combined with improved technology has resulted in a large increase in detection of polyps. Most polyps detected at screening colonoscopy are small (<10 mm) or diminutive (<6 mm) and, in particular the latter, have a very small chance of containing advanced features or cancer. The main reason for resecting small adenomas and sending them to histopathology serves to inform on the future surveillance intervals. Being able to diagnose adenomas in vivo would allow for them to be resected and discarded, saving the costs associated with histopathology. Diagnosing distal hyperplastic polyps in vivo would allow for these to be left in situ reducing the risks associated with polypectomy. There are now a number of new technologies that could potentially make optical diagnosis a reality. Resect and discard policy is an attractive concept for patients, gastroenterologists and health service providers and would present an enticing change to current clinical practice.

A prospective dual-center proof-of-principle study evaluating the incremental benefit of narrow-band imaging with a fixed zoom function in real-time prediction of polyp histology. Can we resect and discard?

BACKGROUND

Advancements in endoscopic technology have increased the ability to distinguish neoplastic polyps during colonoscopy. If a minimum accuracy can be achieved, then a resect-and-discard model can be implemented, although studies to date have demonstrated limited success, especially in the assessment of serrated polyps.

OBJECTIVE

To perform a proof-of-principle study assessing the accuracy of narrow-band imaging with near focus in predicting polyp histology including serrated polyps and to determine whether the minimum requirements can be achieved for a resect-and-discard policy.

DESIGN

Dual-center, prospective case series.

SETTING

Two tertiary-care referral endoscopic centers in Australia.

PATIENTS

Two hundred consecutive patients undergoing colonoscopy for routine indications were recruited.

INTERVENTIONS

Any polyps identified were assessed by using standard white light followed by narrow-band imaging with near focus for Kudo pit patterns and modified Sano capillary patterns. Based on this assessment and the macroscopic appearance, the polyp histology was predicted and subsequently compared with histopathology results.

MAIN OUTCOME MEASUREMENTS

Correlation in postpolypectomy surveillance intervals between endoscopic and pathologic assessments as well as negative predictive value for rectosigmoid hyperplastic polyps.

RESULTS

There was a 96% agreement for surveillance intervals between endoscopic assessment and histology by using the American Society for Gastrointestinal Endoscopy guidelines. There was a 96% negative predictive value in assessing rectosigmoid hyperplastic polyps.

LIMITATIONS

Because this was a proof-of-principle study, there was no control arm, and there were small numbers, especially in assessing subgroups. The results have limited generalizability with the training requirements for polyp recognition, with confidence to be determined.

CONCLUSION

Narrow-band imaging with near focus can predict polyp histology (including serrated polyps) accurately in the hands of trained endoscopists. Further studies with larger numbers are required to further validate this practice.

High Definition Colonoscopy Combined with i-SCAN Imaging Technology Is Superior in the Detection of Adenomas and Advanced Lesions Compared to High Definition Colonoscopy Alone

Background. Improved detection of adenomatous polyps using i-SCAN has mixed results in small studies. Utility of i-SCAN as a primary surveillance modality for colorectal cancer screening during colonoscopy is uncertain. Aim. Comparing high definition white light endoscopy (HDWLE) to i-SCAN in their ability to detect adenomas during colonoscopy. Methods. Prospective cohort study of 1936 average risk patients who had a screening colonoscopy at an ambulatory procedure center. Patients underwent colonoscopy with high definition white light endoscopy withdrawal versus i-SCAN withdrawal during endoscopic screening exam. Primary outcome measurement was adenoma detection rate for i-SCAN versus high definition white light endoscopy. Secondary measurements included polyp size, pathology, and morphology. Results. 1007 patients underwent colonoscopy with i-SCAN and 929 with HDWLE. 618 adenomas were detected in the i-SCAN group compared to 402 in the HDWLE group (p < 0.01). More advanced adenomas (≥10 mm) were found by i-SCAN, 79 versus 47 (p = 0.021) and based upon histology alone 37 versus 18 (p = 0.028). Conclusions. i-SCAN detected significantly more adenomas and advanced adenomas compared to high definition white light endoscopy.

Accuracy of i-Scan for Optical Diagnosis of Colonic Polyps: A Meta-Analysis

Background

i-Scan is a novel virtual chromoendoscopy system designed to enhance surface and vascular patterns to improve optical diagnostic performance. Numerous prospective studies have been done to evaluate the accuracy of i-Scan in differentiating colonic neoplasms from non-neoplasms. i-Scan could be an effective endoscopic technique for optical diagnosis of colonic polyps.

Objective

Our aim of this study was to perform a meta-analysis of published data to establish the diagnostic accuracy of i-Scan for optical diagnosis of colonic polyps.

Methods

We searched PubMed, Medline, Elsevier ScienceDirect and Cochrane Library databases. We used a bivariate meta-analysis following a random effects model to summarize the data and plotted hierarchical summary receiver-operating characteristic (HSROC) curves. The area under the HSROC curve (AUC) serves as an indicator of the diagnostic accuracy.

Results

The meta-analysis included a total of 925 patients and 2312 polyps. For the overall studies, the area under the HSROC curve was 0.96. The summary sensitivity was 90.4% (95%CI 85%-94.1%) and specificity was 90.9% (95%CI 84.3%-94.9%). In 11 studies predicting polyps histology in real-time, the summary sensitivity and specificity was 91.5% (95%CI 85.7%-95.1%) and 92.1% (95%CI 84.5%-96.1%), respectively, with the AUC of 0.97. For three different diagnostic criteria (Kudo, NICE, others), the sensitivity was 86.3%, 93.0%, 85.0%, respectively and specificity was 84.8%, 94.4%, 91.8%, respectively.

Conclusions

Endoscopic diagnosis with i-Scan has accurate optical diagnostic performance to differentiate neoplastic from non-neoplastic polyps with an area under the HSROC curve exceeding 0.90. Both the sensitivity and specificity for diagnosing colonic polyps are over 90%.

Chromocolonoscopy

Chromoendoscopy techniques improve the visualization of mucosal structures. This article reviews and summarizes key studies addressing the impact of chromoendoscopy on colonic neoplasia detection and differentiation of neoplastic from non-neoplastic polyps in average and high-risk populations, including patients with colonic inflammatory bowel disease (IBD). In this context, there are convincing data that chromoendoscopy differentiates neoplastic from non-neoplastic polyps in average-risk populations with high accuracy. Moreover, dye-based chromoendoscopy improves neoplasia detection in colonic IBD surveillance.

New paradigms in polypectomy: resect and discard, diagnose and disregard

Polypectomy at colonoscopy has been shown to reduce the subsequent risk of colorectal cancer. With the advent of national screening programs, the number of colonoscopies performed has increased worldwide. In addition, the recent drive for quality improvement combined with advances in colonoscopic technology has resulted in increased numbers of polyps detected, resected, and sent for histopathology leading to spiraling costs associated with the procedure. Being able to diagnose small polyps in vivo (optical diagnosis) would allow for adenomas to be resected and discarded without the need to retrieve them or send them for formal histopathology.

Tools for polyp histology prediction

Although removal of adenomatous polyps has been shown to decrease the risk of colon cancer, distal hyperplastic polyps are thought to not have malignant potential. Most polyps detected during colonoscopy are diminutive (≤ 5 mm) and rarely harbor advanced histology, such as high-grade dysplasia or cancer. Therefore, predicting histology in real-time during colonoscopy can potentially decrease the enormous expenditure that ensues from universal histopathologic evaluation of polyps, and several novel imaging technologies have been developed and tested over the past decade for this purpose. Of these different technologies, electronic chromoendoscopy seems to strike a fair balance between accuracy, feasibility, and cost.

Electronic chromoendoscopy

Electronic chromoendoscopy technologies provide image enhancement and may improve the diagnosis of mucosal lesions. Although strides have been made in standardization of image characterization, especially with NBI, further image-to-pathology correlation and validation are required. There is promise for the development of a resect and discard policy for diminutive adenomas by using electronic chromoendoscopy; however, before this can be adopted, further community-based studies are needed. Further validated training tools for NBI, FICE, and i-SCAN will also be required for the use of these techniques to become widespread.

Advances, problems, and complications of polypectomy

The major role of colonoscopy with polypectomy in reducing the incidence of and mortality from colorectal cancer has been firmly established. Yet there is cause to be uneasy. One of the most striking recent findings is that there is an alarmingly high incomplete polyp removal rate. This phenomenon, together with missed polyps during screening colonoscopy, is thought to be responsible for the majority of interval cancers. Knowledge of serrated polyps needs to broaden as well, since they are quite often missed or incompletely removed. Removal of small and diminutive polyps is almost devoid of complications. Cold snare polypectomy seems to be the best approach for these lesions, with biopsy forcep removal reserved only for the tiniest of polyps. Hot snare or hot biopsy forcep removal of these lesions is no longer recommended. Endoscopic mucosal resection and endoscopic submucosal dissection have proven to be effective in the removal of large colorectal lesions, avoiding surgery in the majority of patients, with acceptably low complication rates. Variants of these approaches, as well as new hybrid techniques, are being currently tested. In this paper, we review the current status of the different approaches in removing polypoid and nonpolypoid lesions of the colon, their complications, and future directions in the prevention of colorectal cancer.

Equipment-based image-enhanced endoscopy for differentiating colorectal polyps

The use of colonoscopy for the screening and surveillance of colorectal cancer has increased. However, the miss rate of advanced colorectal neoplasm is known to be 2% to 6%, which could be affected by the image intensity of colorectal lesions. Image-enhanced endoscopy (IEE) is capable of highlighting lesions, which can improve the colorectal adenoma detection rate and diagnostic accuracy. Equipment-based IEE methods, such as narrow band imaging (NBI), Fujinon intelligent color enhancement (FICE), and i-Scan, are used to observe the mucosal epithelium of the microstructure and capillaries of the lesion, and are helpful in the detection and differential diagnosis of colorectal tumors. Although NBI is similar to chromoendoscopy in terms of adenoma detection rates, NBI can be used to differentiate colorectal polyps and to predict the submucosal invasion of malignant tumors. It is also known that FICE and i-Scan are similar to NBI in their detection rates of colorectal lesions. Through more effective and advanced endoscopic equipment, diagnostic accuracy could be improved and new treatment paradigms developed.

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.

Advances in colonoscopy

Colonoscopy with polypectomy has been established as the major prevention and detection strategy for colorectal cancer for over a decade. Over this period advances in colonoscopic imaging, polyp detection, prediction of histopathology and polypectomy techniques have all been seen; however, the true magnitude of the limitations of colonoscopy has only recently been widely recognized. The rate and location of missed or interval cancers after complete colonoscopy appears to be influenced by the operator-dependency of colonoscopy and failure of conventional practices to detect and treat adenomatous, and possibly more importantly, non-adenomatous colorectal cancer precursors. Consequently, studies that expand our understanding of these factors and advances that aim to improve colonoscopy, polypectomy, and cancer protection are of critical importance.

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.

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.