Combining autofluorescence imaging and narrow-band imaging for the differentiation of adenomas from non-neoplastic colonic polyps among experienced and non-experienced endoscopists

Optical Polyp Diagnosis in the Era or Artificial Intelligence

The development of new image enhancement modalities and improved endoscopic imaging quality has not led to increased adoption of resect-and-discard in routine practice. Studies have shown that endoscopists have the capacity to achieve quality thresholds to perform optical diagnosis; however, this has not led to acceptance of optical diagnosis as a replacement for pathology for diminutive (1-5 mm) polyps. In recent years, artificial intelligence (AI)-based computer-assisted characterization of diminutive polyps has recently emerged as a strategy that could potentially represent a breakthrough technology to enable widespread adoption of resect-and-discard. Recent evidence suggests that pathology-based diagnosis is suboptimal, as polyp nonretrieval, fragmentation, sectioning errors, incorrect diagnosis as "normal mucosa," and interpathologist variability limit the efficacy of pathology for the diagnosis of 1-5 mm polyps. New paradigms in performing polyp diagnosis with or without AI have emerged to compete with pathology in terms of efficacy. Strategies, such as autonomous AI, AI-assisted human diagnosis, AI-unassisted human diagnosis, and combined strategies have been proposed as potential paradigms for resect-and-discard, although further research is still required to determine the optimal strategy. Implementation studies with high patient acceptance, where polyps are truly being discarded without histologic diagnosis, are paving the way toward normalizing resect-and-discard in routine clinical practice. Ultimately the largest challenges for computer-assisted characterization remain liability perceptions from endoscopists. The potential benefits of AI-based resect-and-discard are many, with very little potential harm. Real-world implementation studies are therefore required to pave the way for the acceptability of such strategies in routine practice.

Autonomous Artificial Intelligence vs Artificial Intelligence-Assisted Human Optical Diagnosis of Colorectal Polyps: A Randomized Controlled Trial

BACKGROUND & AIMS

Artificial intelligence (AI)-based optical diagnosis systems (CADx) have been developed to allow pathology prediction of colorectal polyps during colonoscopies. However, CADx systems have not yet been validated for autonomous performance. Therefore, we conducted a trial comparing autonomous AI to AI-assisted human (AI-H) optical diagnosis.

METHODS

We performed a randomized noninferiority trial of patients undergoing elective colonoscopies at 1 academic institution. Patients were randomized into (1) autonomous AI-based CADx optical diagnosis of diminutive polyps without human input or (2) diagnosis by endoscopists who performed optical diagnosis of diminutive polyps after seeing the real-time CADx diagnosis. The primary outcome was accuracy in optical diagnosis in both arms using pathology as the gold standard. Secondary outcomes included agreement with pathology for surveillance intervals.

RESULTS

A total of 467 patients were randomized (238 patients/158 polyps in the autonomous AI group and 229 patients/179 polyps in the AI-H group). Accuracy for optical diagnosis was 77.2% (95% confidence interval [CI], 69.7-84.7) in the autonomous AI group and 72.1% (95% CI, 65.5-78.6) in the AI-H group (P = .86). For high-confidence diagnoses, accuracy for optical diagnosis was 77.2% (95% CI, 69.7-84.7) in the autonomous AI group and 75.5% (95% CI, 67.9-82.0) in the AI-H group. Autonomous AI had statistically significantly higher agreement with pathology-based surveillance intervals compared to AI-H (91.5% [95% CI, 86.9-96.1] vs 82.1% [95% CI, 76.5-87.7]; P = .016).

CONCLUSIONS

Autonomous AI-based optical diagnosis exhibits noninferior accuracy to endoscopist-based diagnosis. Both autonomous AI and AI-H exhibited relatively low accuracy for optical diagnosis; however, autonomous AI achieved higher agreement with pathology-based surveillance intervals. (ClinicalTrials.gov, Number NCT05236790).

EARLY STAGES OF COLORECTAL CANCER CHARACTERIZATION BY AUTOFLUORESCENCE 3D MICROSCOPY: A PRELIMINARY STUDY

BACKGROUND

Colorectal cancer is one of the most prevalent pathologies worldwide whose prognosis is linked to early detection. Colonoscopy is the gold standard for screening, and diagnosis is usually made histologically from biopsies. Aiming to reduce the inspection and diagnostic time as well as the biopsies and resources involved, other techniques are being promoted to conduct accurate in vivo colonoscopy assessments. Optical biopsy aims to detect normal and neoplastic tissues analysing the autofluorescence spectrum based on the changes in the distribution and concentration of autofluorescent molecules caused by colorectal cancer. Therefore, the autofluorescence contribution analysed by image processing techniques could be an approach to a faster characterization of the target tissue.

OBJECTIVE

Quantify intensity parameters through digital processing of two data sets of three-dimensional widefield autofluorescence microscopy images, acquired by fresh colon tissue samples from a colorectal cancer murine model. Additionally, analyse the autofluorescence data to provide a characterization over a volume of approximately 50 µm of the colon mucosa for each image, at second (2nd), fourth (4th) and eighth (8th) weeks after colorectal cancer induction.

METHODS

Development of a colorectal cancer murine model using azoxymethane/dextran sodium sulphate induction, and data sets acquisition of Z-stack images by widefield autofluorescence microscopy, from control and colorectal cancer induced animals. Pre-processing steps of intensity value adjustments followed by quantification and characterization procedures using image processing workflow automation by Fiji's macros, and statistical data analysis.

RESULTS

The effectiveness of the colorectal cancer induction model was corroborated by a histological assessment to correlate and validate the link between histological and autofluorescence changes. The image digital processing methodology proposed was then performed on the three-dimensional images from control mice and from the 2nd, 4th, and 8th weeks after colorectal cancer chemical induction, for each data set. Statistical analyses found significant differences in the mean, standard deviation, and minimum parameters between control samples and those of the 2nd week after induction with respect to the 4th week of the first experimental study. This suggests that the characteristics of colorectal cancer can be detected after the 2nd week post-induction.

CONCLUSION

The use of autofluorescence still exhibits levels of variability that prevent greater systematization of the data obtained during the progression of colorectal cancer. However, these preliminary outcomes could be considered an approach to the three-dimensional characterization of the autofluorescence of colorectal tissue, describing the autofluorescence features of samples coming from dysplasia to colorectal cancer.

BACKGROUND

• A new digital image processing method was developed to measure intensity in 3D autofluorescence images of colorectal samples using a CRC mouse model.

BACKGROUND

• This method showed that autofluorescence intensity in colon mucosa is similar in healthy tissue but changes significantly in tumor development.

BACKGROUND

• Statistical analysis revealed CRC traits detectable from the second week post-induction, aiding in early CRC detection.

BACKGROUND

• The study provides a basis for 3D autofluorescence characterization in colorectal tissue from dysplasia to cancer, although variability in autofluorescence limits data systematization during cancer progression.

From Staining Techniques to Artificial Intelligence: A Review of Colorectal Polyps Characterization

This review article provides a comprehensive overview of the evolving techniques in image-enhanced endoscopy (IEE) for the characterization of colorectal polyps, and the potential of artificial intelligence (AI) in revolutionizing the diagnostic accuracy of endoscopy. We discuss the historical use of dye-spray and virtual chromoendoscopy for the characterization of colorectal polyps, which are now being replaced with more advanced technologies. Specifically, we focus on the application of AI to create a "virtual biopsy" for the detection and characterization of colorectal polyps, with potential for replacing histopathological diagnosis. The incorporation of AI has the potential to provide an evolutionary learning system that aids in the diagnosis and management of patients with the best possible outcomes. A detailed analysis of the literature supporting AI-assisted diagnostic techniques for the detection and characterization of colorectal polyps, with a particular emphasis on AI's characterization mechanism, is provided. The benefits of AI over traditional IEE techniques, including the reduction in human error in diagnosis, and its potential to provide an accurate diagnosis with similar accuracy to the gold standard are presented. However, the need for large-scale testing of AI in clinical practice and the importance of integrating patient data into the diagnostic process are acknowledged. In conclusion, the constant evolution of IEE technology and the potential for AI to revolutionize the field of endoscopy in the future are presented.

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.

Advanced endoscopy technologies to improve the detection and characterisation of colorrectal polyps

Colorectal cancer is a major health problem. An improvement to its survival has been demonstrated by performing colonoscopy screenings and removing its precursor lesions: polyps. However, colonoscopy is not infallible and multiple strategies have been proposed aimed at improving the quality thereof. This report describes the endoscopic systems available to improve the detection and characterization of polyps, the different classifications for histological prediction and the current indications of advanced endoscopic diagnostic techniques.

A Review of New and Emerging Techniques For Optical Diagnosis of Colonic Polyps

BACKGROUND AND AIMS

Endoscopic imaging is a rapidly progressing field and benefits from miniaturization of advanced imaging technologies, which may allow accurate real-time characterization of lesions. The concept of the "optical biopsy" to predict polyp histology has gained prominence in recent years and may become clinically applicable with the advent of new imaging technology. This review aims to discuss current evidence and examine the emerging technologies as applied to the optical diagnosis of colorectal polyps.

METHODS

A structured literature search and review has been carried out of the evidence for diagnostic accuracy of image-enhanced endoscopy and emerging endoscopic imaging technologies. The image-enhanced endoscopy techniques are reviewed, including their basic scientific principles and current evidence for effectiveness. These include the established image-enhancement technologies such as narrow-band imaging, i-scan, and Fuji intelligent chromoendoscopy. More recent technologies including optical enhancement, blue laser imaging, and linked color imaging are discussed. Adjunctive imaging techniques in current clinical use are discussed, such as autofluorescence imaging and endocytoscopy. The emerging advanced imaging techniques are reviewed, including confocal laser endomicroscopy, optical coherence tomography, and Raman spectroscopy.

CONCLUSIONS

Large studies of the established image-enhancement techniques show some role for the optical diagnosis of polyp histology, although results have been mixed, and at present only the technique of narrow-band imaging is appropriate for the diagnosis of low-risk polyps when used by an expert operator. Other image-enhancement techniques will require further study to validate their accuracy but show potential to support the use of a "resect-and-discard" approach to low-risk polyps. New technologies show exciting potential for real-time diagnosis, but further clinical studies in humans have yet to be performed.

Autofluorescence Imaging Reflects the Nuclear Enlargement of Tumor Cells as well as the Cell Proliferation Ability and Aberrant Status of the p53, Ki-67, and p16 Genes in Colon Neoplasms

BACKGROUND

Autofluorescence imaging (AFI) is useful for diagnosing colon neoplasms, but what affects the AFI intensity remains unclear. This study investigated the association between AFI and the histological characteristics, aberrant methylation status, and aberrant expression in colon neoplasms.

METHODS

Fifty-three patients with colorectal neoplasms who underwent AFI were enrolled. The AFI intensity (F index) was compared with the pathological findings and gene alterations. The F index was calculated using an image analysis software program. The pathological findings were assessed by the tumor crypt density, cell densities, and N/C ratio. The aberrant methylation of p16, E-cadherin, Apc, Runx3, and hMLH1 genes was determined by a methylation-specific polymerase chain reaction. The aberrant expression of p53 and Ki-67 was evaluated by immunohistochemical staining.

RESULTS

An increased N/C ratio, the aberrant expression of p53, Ki-67, and the altered methylation of p16 went together with a lower F index. The other pathological findings and the methylation status showed no association with the F index.

CONCLUSIONS

AFI reflects the nuclear enlargement of tumor cells, the cell proliferation ability, and the altered status of cell proliferation-related genes, indicating that AFI is a useful and practical method for predicting the dysplastic grade of tumor cells and cell proliferation.

Comparison of diagnostic efficacy between AFI, NBI, and AFI combined with NBI for colonic cancers: A meta-analysis

BACKGROUND/AIMS

Advanced endoscopic imaging technologies have been used for the early detection and differentiation of colonic cancers recently. We aim to evaluate the diagnostic efficacy of autofluorescence imaging (AFI), narrow-band imaging (NBI), and AFI combined with NBI for colonic cancers.

MATERIALS AND METHODS

We searched Medline/PubMed, Embase, Web of Science, and Cochrane Library databases for relevant articles. A random-effects model was used to assess diagnostic efficacy. Heterogeneity was tested by the I2 statistic and Chi-square test. Meta-regression was used to analyze the sources of heterogeneity.

RESULTS

The pooled sensitivities for AFI, NBI, and AFI plus NBI were 0.84 (95% confidence interval (CI) 0.82-0.87), 0.84 (95% CI 0.81-0.86), and 0.93 (95% CI 0.90-0.95), respectively. The pooled specificities were 0.44 (95% CI 0.40-0.48), 0.69 (95% CI 0.65-0.72), and 0.69 (95% CI 0.64-0.74), respectively. The sensitivity estimate was significantly higher for AFI plus NBI than AFI or NBI alone (P = 0.041), and the specificity estimates were significantly higher for NBI and AFI plus NBI than AFI (P = 0.031).The pooled diagnostic odds ratio for AFI, NBI, and AFI plus NBI were 8.71 (95% CI 2.90-26.16), 16.02 (95% CI 7.05-36.39), and 57.55 (95% CI 9.82-337.33), respectively. Furthermore, the summary receiver operating characteristic curve area under the curve for AFI, NBI, and AFI plus NBI were 0.8125 with Q* =0.7469, 0.8696 with Q* =0.8001, and 0.9447 with Q* =0.8835, respectively. The Q* index for AFI plus NBI was significantly higher than AFI or NBI alone (P = 0.048).

CONCLUSION

The combination of AFI and NBI was associated with increased diagnostic value for colonic cancers compared with AFI and NBI alone.

Hyperspectral imaging fluorescence excitation scanning for colon cancer detection

Optical spectroscopy and hyperspectral imaging have shown the potential to discriminate between cancerous and noncancerous tissue with high sensitivity and specificity. However, to date, these techniques have not been effectively translated to real-time endoscope platforms. Hyperspectral imaging of the fluorescence excitation spectrum represents new technology that may be well suited for endoscopic implementation. However, the feasibility of detecting differences between normal and cancerous mucosa using fluorescence excitation-scanning hyperspectral imaging has not been evaluated. The goal of this study was to evaluate the initial feasibility of using fluorescence excitation-scanning hyperspectral imaging for measuring changes in fluorescence excitation spectrum concurrent with colonic adenocarcinoma using a small pre-pilot-scale sample size. Ex vivo analysis was performed using resected pairs of colorectal adenocarcinoma and normal mucosa. Adenocarcinoma was confirmed by histologic evaluation of hematoxylin and eosin (H&E) permanent sections. Specimens were imaged using a custom hyperspectral imaging fluorescence excitation-scanning microscope system. Results demonstrated consistent spectral differences between normal and cancerous tissues over the fluorescence excitation range of 390 to 450 nm that could be the basis for wavelength-dependent detection of colorectal cancers. Hence, excitation-scanning hyperspectral imaging may offer an alternative approach for discriminating adenocarcinoma from surrounding normal colonic mucosa, but further studies will be required to evaluate the accuracy of this approach using a larger patient cohort.

New technologies and techniques to improve adenoma detection in colonoscopy

Adenoma detection rate (ADR) is a key component of colonoscopy quality assessment, with a direct link between itself and future mortality from colorectal cancer. There are a number of potential factors, both modifiable and non-modifiable that can impact upon ADR. As methods, understanding and technologies advance, so should our ability to improve ADRs, and thus, reduce colorectal cancer mortality. This article will review new technologies and techniques that improve ADR, both in terms of the endoscopes themselves and adjuncts to current systems. In particular it focuses on effective techniques and behaviours, developments in image enhancement, advancement in endoscope design and developments in accessories that may improve ADR. It also highlights the key role that continued medical education plays in improving the quality of colonoscopy and thus ADR. The review aims to present a balanced summary of the evidence currently available and does not propose to serve as a guideline.

Detection and miss rates of autofluorescence imaging of adenomatous and polypoid lesions during colonoscopy: a systematic review and meta-analysis

BACKGROUND AND STUDY AIMS

Autofluorescence imaging (AFI) is an endoscopic imaging technique used to increase the detection of premalignant gastrointestinal lesions, and it has gradually become popular in recent years. This meta-analysis was performed to examine whether AFI provides greater efficacy in the detection of adenomatous and polypoid lesions and can even prevent the failure to detect a single adenoma or polyp. The aim of the study was to systematically review the efficacy of AFI in increasing detection rates and decreasing miss rates.

METHODS

Pertinent articles were identified through a search of databases up to December 2013 that included patients who had undergone two same-day colonoscopies (AFI and white light endoscopy [WLE]), followed by polypectomy. Fixed and random effects models were used to detect significant differences between AFI and WLE in regard to adenoma detection rate (ADR), polyp detection rate (PDR), adenoma miss rate (AMR), polyp miss rate (PMR), and procedural time.

RESULTS

A total of 1199 patients from six eligible studies met the inclusion criteria. No significant differences were found in ADR (odds ratio [OR] 1.01; 95 % confidence interval [95 %CI] 0.74 - 1.37), PDR (OR 0.86; 95 %CI 0.57 - 1.30), or advanced ADR (OR 1.22; 95 %CI 0.69 - 2.17). The AMR (OR 0.62; 95 %CI 0.44 - 0.86) and PMR (OR 0.64; 95 %CI 0.48 - 0.85) by AFI were significantly lower than those by WLE. The procedural time of AFI was significantly longer than that of WLE (mean 8.00 minutes; 95 %CI 1.59 - 14.41). Subgroup meta-analysis for the other characteristics was not performed because of insufficiency of the primary data.

CONCLUSIONS

AFI decreases AMR and PMR significantly compared with WLE but does not improve ADR or PDR. AMR and PMR may be decreased by using AFI in flat and small lesions or when less experienced endoscopists perform the procedure.

Screening colonoscopy: what is the most reliable modality for the detection and characterization of colorectal lesions?

Colonoscopy is considered the best modality for the detection and treatment of colorectal polyps. However, some polyps still may not be detected. Although conventional white-light endoscopy is the gold standard for the detection of colorectal polyps, up to a fifth of lesions may be missed on screening colonoscopy, especially non-polypoid colorectal neoplasms. Recently, many studies have reported on various endoscopic modalities that improve the detection and characterization of colorectal lesions. Newly developed modalities might be helpful to recognize colorectal lesions; however, careful observation is required to identify flat/depressed lesions as well as hidden polyps during screening and surveillance colonoscopy.

Novel imaging modalities for immune cell monitoring in the intestine

PURPOSE OF REVIEW

The introduction of novel molecular imaging modalities that can not only define disease states on the basis of structural changes and morphology, but also allow in-vivo visualization and characterization of molecular and biochemical alterations on a cellular level add a new dimension to our current diagnostic possibilities. The advents of innovative endoscopic devices coupled with the introduction of novel targeting ligands contribute to the recent advances made in the field of molecular imaging. The purpose of this review is to present and discuss the concepts and the potential of novel endoscopic imaging modalities for immune cell monitoring in the intestine.

RECENT FINDINGS

Recent progress concerning molecular imaging studies in animals and human patients implicates that this approach can be used to improve detection of mucosal lesions in wide-field imaging and for in-vivo characterization of the mucosa with the ultimate goal of assessing the likelihood of response to targeted therapy with biological agents. In particular, molecular endomicroscopy for assessment of mucosal immune responses ('immunoendoscopy') emerges as a novel approach for optimized endoscopic diagnosis and individualized therapy.

SUMMARY

Molecular imaging modalities in the intestine have the immediate potential to have an impact on current clinical practice and could therefore open new frontiers for clinical endoscopy and give hope for improved diagnosis and targeted therapies.

Evaluation of the effectiveness of color intensity analysis using a second-generation autofluorescence imaging system for diminutive colorectal polyp differentiation

BACKGROUND AND AIM

We previously reported the effectiveness of color tone intensity analysis using autofluorescence imaging (AFI) for distinguishing between colorectal neoplastic and non-neoplastic lesions. Moreover, a second-generation AFI system has become commercially available in Japan. In the present study, we assessed the effectiveness of color tone intensity analysis using a second-generation AFI system for evaluating diminutive colorectal lesions.

METHODS

We retrospectively reviewed the cases of 35 consecutive patients with 101 diminutive colorectal lesions that were examined using a second-generation AFI system and resected at the Jikei University Hospital. We estimated the mean green-to-red (G/R) ratio - obtained by dividing the green color tone intensity by the red color tone intensity - of the lesions and compared the values of the neoplastic and non-neoplastic lesions. We also assessed the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the AFI system for neoplastic lesion identification.

RESULTS

The mean G/R ratios of the non-neoplastic and neoplastic lesions were 1.06 and 0.87, respectively; the mean G/R ratio significantly differed between the neoplastic and non-neoplastic lesions. Using the second-generation AFI system, neoplastic lesions were identified with a sensitivity, specificity, PPV, and NPV of 94.2%, 91.8%, 92.5%, and 93.8%, respectively.

CONCLUSION

Color intensity analysis of diminutive colorectal polyps using the second generation AFI system could effectively distinguish between neoplastic and non-neoplastic lesions.

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.

Quality in colonoscopy: European perspectives and practice

Colonoscopy is the 'gold standard' investigation of the colon. High quality colonoscopy is essential to diagnose early cancer and reduce its incidence through the detection and removal of pre-malignant adenomas. In this review, we discuss the key components of a high quality colonoscopy, review methods for improving quality, emerging technologies that have the potential to improve quality and highlight areas for future work.

Diagnostic performance of narrowed spectrum endoscopy, autofluorescence imaging, and confocal laser endomicroscopy for optical diagnosis of colonic polyps: a meta-analysis

BACKGROUND

Novel endoscopic technologies could allow optical diagnosis and resection of colonic polyps without histopathological testing. Our aim was to establish the sensitivity, specificity, and real-time negative predictive value of three types of narrowed spectrum endoscopy (narrow-band imaging [NBI], image-enhanced endoscopy [i-scan], and Fujinon intelligent chromoendoscopy [FICE]), confocal laser endomicroscopy (CLE), and autofluorescence imaging for differentiation between neoplastic and non-neoplastic colonic lesions.

METHODS

We identified relevant studies through a search of Medline, Embase, PubMed, and the Cochrane Library. Clinical trials and observational studies were eligible for inclusion when the diagnostic performance of NBI, i-scan, FICE, autofluorescence imaging, or CLE had been assessed for differentiation, with histopathology as the reference standard, and for which a 2 × 2 contingency table of lesion diagnosis could be constructed. We did a random-effects bivariate meta-analysis using a non-linear mixed model approach to calculate summary estimates of sensitivity and specificity, and plotted estimates in a summary receiver-operating characteristic curve.

FINDINGS

We included 91 studies in our analysis: 56 were of NBI, ten of i-scan, 14 of FICE, 11 of CLE, and 11 of autofluorescence imaging (more than one of the investigated modalities assessed in eight studies). For NBI, overall sensitivity was 91·0% (95% CI 88·6-93·0), specificity 85·6% (81·3-89·0), and real-time negative predictive value 82·5% (75·4-87·9). For i-scan, overall sensitivity was 89·3% (83·3-93·3), specificity 88·2% (80·3-93·2), and real-time negative predictive value 86·5% (78·0-92·1). For FICE, overall sensitivity was 91·8% (87·1-94·9), specificity 83·5% (77·2-88·3), and real-time negative predictive value 83·7% (77·5-88·4). For autofluorescence imaging, overall sensitivity was 86·7% (79·5-91·6), specificity 65·9% (50·9-78·2), and real-time negative predictive value 81·5% (54·0-94·3). For CLE, overall sensitivity was 93·3% (88·4-96·2), specificity 89·9% (81·8-94·6), and real-time negative predictive value 94·8% (86·6-98·1).

INTERPRETATION

All endoscopic imaging techniques other than autofluorescence imaging could be used by appropriately trained endoscopists to make a reliable optical diagnosis for colonic lesions in daily practice. Further research should be focused on whether training could help to improve negative predictive values.

FUNDING

None.

Real-time histology in colonoscopy

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

Colonic polyps: are we ready to resect and discard?

Colorectal cancer represents a major cause of mortality in Western countries, and population-based colonoscopy screening is supported by official guidelines. A significant determinant of the cost of colonoscopy screening/surveillance is driven by polypectomy of diminutive (≤5 mm) lesions. When considering the low prevalence of advanced neoplasia within diminutive polyps, the additional cost of pathologic examination is mainly justified by the need to differentiate between precancerous adenomatous versus hyperplastic polyps. The aim of this review is to summarize the data supporting the clinical application of a resect and discard strategy, also addressing the potential pitfalls associated with this approach.

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

BACKGROUND AND AIM

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Endoscopic features of sessile serrated adenomas: validation by international experts using high-resolution white-light endoscopy and narrow-band imaging

BACKGROUND

Sessile serrated adenomas/polyps (SSAs/Ps) are premalignant lesions susceptible to being easily overlooked by endoscopists. A detailed description of the endoscopic appearance of SSAs/Ps might help endoscopists to recognize these lesions to improve the effectiveness of colonoscopy.

OBJECTIVE

To identify various endoscopic features of SSAs/Ps using high-resolution white-light endoscopy (HR-WLE) and narrow-band imaging (NBI).

DESIGN

Retrospective image evaluation study.

SETTING

Single tertiary referral center.

PATIENTS

Forty-5 patients with serrated polyposis syndrome undergoing surveillance colonoscopies.

INTERVENTION

HR-WLE and NBI images of 150 polyps (50 SSAs/Ps, 50 hyperplastic polyps [HPs], and 50 adenomas) were systematically assessed by 5 experts using various endoscopic descriptors.

MAIN OUTCOME MEASUREMENTS

The prevalence of specific endoscopic features observed in SSAs/Ps versus HPs.

RESULTS

Multivariate analysis demonstrated that indistinct borders (OR, 3.11; 95% CI, 1.57-6.15) and a cloud-like surface (OR, 2.65; 95% CI, 1.21-5.78) were associated with SSA/P histology on HR-WLE. On NBI, a cloud-like surface (OR, 4.91; 95% CI, 2.42-9.97), indistinct borders (OR, 2.38; 95% CI, 1.14-4.96), irregular shape (OR, 3.17; 95% CI, 1.59-6.29), and dark spots inside the crypts (OR, 2.05; 95% CI, 1.02-4.11) were found to be endoscopic predictors of SSA/P histology. The sensitivity, specificity, and accuracy of NBI for differentiating serrated polyps containing either none or all 4 endoscopic SSA/P features were, respectively, 89%, 96%, and 93%.

LIMITATIONS

Retrospective, image evaluation analysis.

CONCLUSIONS

The current study demonstrates that SSAs/Ps possess several specific endoscopic features compared with HPs. Recognition of these characteristics might assist endoscopists in the differentiation of these lesions and could possibly facilitate endoscopic detection of these rather subtle lesions.

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

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

New paradigms for colonoscopic management of diminutive colorectal polyps: predict, resect, and discard or do not resect?

The possibility to predict in vivo the histology of colorectal polyps by advanced endoscopic imaging has resulted in the implementation of a more conservative management for diminutive lesions detected at colonoscopy. In detail, a predict-and-do-not-resect strategy has been proposed for diminutive lesions located in the rectosigmoid tract, whilst a predict-resect-and-discard policy has been advocated for nonrectosigmoid diminutive polyps. Recently, the American Society for Gastrointestinal Endoscopy set required thresholds to be met, before allowing the adoption of these policies in the clinical field. The ability of current endoscopic imaging in reaching these thresholds would depend on a complex interaction among the accuracy of advanced endoscopic imaging in differentiating between adenomatous and hyperplastic lesions, the prevalence of (advanced) neoplasia within diminutive lesions, and the type of surveillance intervals recommended. Aim of this review is to summarize the data supporting the application of both a predict-and-do-not-resect and a predict-resect-and-discard policies, also addressing the potential pitfalls associated with these strategies.

Diagnostic accuracy of narrow-band imaging for the differentiation of neoplastic from non-neoplastic colorectal polyps: a meta-analysis

AIM

Narrow-band imaging (NBI) is a novel imaging technology that makes the superficial vasculature of gastrointestinal mucosa visible. However, the real accuracy for the differentiation of neoplastic from non-neoplastic polyps by NBI for the colorectum is still unknown.

METHOD

A meta-analysis was carried out of studies which assessed the precision of NBI in the diagnosis of colorectal neoplastic polyps. Searches included PubMed and Embase and two reviewers independently assessed their quality with a modified version of the quadas and stard tools. The study pooled estimates of sensitivity, specificity, diagnostic odds ratio (DOR) and area under the curve (AUC).

RESULTS

There were 11 relevant original papers which fulfilled the inclusion criteria. The pooled sensitivity and specificity were 0.92 (95% CI 0.90-0.93) and 0.83 (95% CI 0.81-0.86) respectively. The AUC for NBI was 0.95 [SE 0.01; DOR 53.72 (95% CI 35.66-80.92)]. The sensitivity and specificity were 0.92 (95% CI 0.90-0.94) and 0.81 (95% CI 0.78-0.84) with magnification, and 0.91 (95% CI 0.88-0.93) and 0.86 (95% CI 0.82-0.89) without magnification. For the mucosal pattern sensitivity and specificity were 0.90 (95% CI 0.85-0.940) and 0.88 (95% CI 0.82-0.93), and for vascular pattern intensity they were 0.92 (95% CI 0.90-0.94) and 0.88 (95% CI 0.83-0.91).

CONCLUSION

Narrow-band imaging, with or without magnification, has a high diagnostic precision for colorectal neoplastic polyps using either vascular pattern intensity or mucosal pattern assessment as the measure.

Real-time optical biopsy of colon polyps with narrow band imaging in community practice does not yet meet key thresholds for clinical decisions

BACKGROUND & AIMS

Accurate optical analysis of colorectal polyps (optical biopsy) could prevent unnecessary polypectomies or allow a "resect and discard" strategy with surveillance intervals determined based on the results of the optical biopsy; this could be less expensive than histopathologic analysis of polyps. We prospectively evaluated real-time optical biopsy analysis of polyps with narrow band imaging (NBI) by community-based gastroenterologists.

METHODS

We first analyzed a computerized module to train gastroenterologists (N = 13) in optical biopsy skills using photographs of polyps. Then we evaluated a practice-based learning program for these gastroenterologists (n = 12) that included real-time optical analysis of polyps in vivo, comparison of optical biopsy predictions to histopathologic analysis, and ongoing feedback on performance.

RESULTS

Twelve of 13 subjects identified adenomas with >90% accuracy at the end of the computer study, and 3 of 12 subjects did so with accuracy ≥90% in the in vivo study. Learning curves showed considerable variation among batches of polyps. For diminutive rectosigmoid polyps assessed with high confidence at the end of the study, adenomas were identified with mean (95% confidence interval [CI]) accuracy, sensitivity, specificity, and negative predictive values of 81% (73%-89%), 85% (74%-96%), 78% (66%-92%), and 91% (86%-97%), respectively. The adjusted odds ratio for high confidence as a predictor of accuracy was 1.8 (95% CI, 1.3-2.5). The agreement between surveillance recommendations informed by high-confidence NBI analysis of diminutive polyps and results from histopathologic analysis of all polyps was 80% (95% CI, 77%-82%).

CONCLUSIONS

In an evaluation of real-time optical biopsy analysis of polyps with NBI, only 25% of gastroenterologists assessed polyps with ≥90% accuracy. The negative predictive value for identification of adenomas, but not the surveillance interval agreement, met the American Society for Gastrointestinal Endoscopy-recommended thresholds for optical biopsy. Better results in community practice must be achieved before NBI-based optical biopsy methods can be used routinely to evaluate polyps; ClinicalTrials.gov number, NCT01638091.

Advances in gastrointestinal endoscopy

Gastrointestinal endoscopy has undergone a remarkable expansion in its capabilities as a result of sophisticated technological advances in recent years. New imaging technologies, novel ablation and resection techniques, cutting-edge endoscope development and creative extraluminal applications have taken gastrointestinal endoscopy to an exciting new level. An update on some of these advances is presented for the physician audience.

Accuracy for optical diagnosis of small colorectal polyps in nonacademic settings

BACKGROUND & AIMS

When small colorectal lesions are accurately characterized, adenomas can be removed and discarded without formal histopathology analysis. Previous studies in an academic setting showed that many lesions can be managed accurately on the basis of their endoscopic image (optical diagnosis). We performed a prospective study to assess the accuracy of optical diagnosis of small colorectal polyps in a nonacademic setting (the DISCOUNT trial) by using high-resolution endoscopy (HRE) and narrow-band imaging (NBI).

METHODS

During colonoscopy, 1 of 3 nonacademic endoscopists characterized small lesions and declared whether this was done with low or high confidence. In cases of high confidence, the endoscopists decided whether lesions should be removed and discarded or whether they could be left in situ. A surveillance interval was then recommended on-site.

RESULTS

Of 215 patients in the study, 108 were found to have 281 small lesions. Of these lesions, 231 were characterized with high confidence by using HRE or NBI; the level of corresponding sensitivity was 77.0% (95% confidence interval, 68.4-83.8), and specificity was 78.8% (95% confidence interval, 70.6-85.2). Of these lesions, 164 were assigned for removal, and 67 were assigned to remain in situ, including 9 adenomas. In 54 patients, a surveillance interval could be recommended on-site that was in line with Dutch guidelines for 44 patients.

CONCLUSIONS

Even though many lesions were characterized by HRE or NBI with high confidence, optical diagnosis in a nonacademic setting proved to be disappointing, with a sensitivity of 77.0% and a specificity of 78.8%. Many lesions were accurately assigned to be removed or remain in situ, although few adenomas were assigned to remain in situ. Also, 19% of on-site recommendations for a surveillance interval proved to be inaccurate.

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

Background

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

Methods

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

Results

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

Conclusions

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

Prevalence of advanced histological features in diminutive and small colon polyps

BACKGROUND

Investigators have proposed "predict, resect, and discard" strategies for diminutive (≤ 5 mm) or small (6-9 mm) polyps to reduce screening colonoscopy costs. Advanced histological features such as villous histology, high-grade dysplasia, and/or cancer in these polyps could deter adoption of these strategies.

OBJECTIVE

Determine the prevalence of advanced histological features in diminutive and small colon polyps.

DESIGN

Retrospective analysis of data from 3 prospective clinical trials.

SETTING

Two tertiary-care referral centers.

PATIENTS

This study involved patients undergoing screening or surveillance colonoscopy.

INTERVENTION

The location, size, and morphology of each polyp detected was documented. Each polyp was then resected, placed in a unique specimen jar, and sent for histopathological evaluation.

MAIN OUTCOME MEASUREMENTS

Rates of advanced histological features (villous histology, high-grade dysplasia, and cancer).

RESULTS

A total of 2361 polyps were detected, removed, and retrieved. Both diminutive and small polyps had a lower frequency of any advanced histological features compared with large polyps (0.5% and 1.5%, respectively vs 15.0%; P < .001 for both comparisons). Polyps <10 mm in size had a lower frequency of advanced histology compared with polyps ≥ 10 mm (0.8% vs 15.0%; P < .001). During sensitivity analysis, the frequency of advanced histological features varied from 0.2% to 0.7% within diminutive polyps, 1.5% to 3.6% within small polyps, and 0.8% to 1.2% within polyps <10 mm.

LIMITATIONS

Retrospective analysis from tertiary-care referral centers; predominantly white, male, veteran patient population resulting in limited generalizability of results.

CONCLUSION

The prevalence of advanced histological features in colon polyps ≤ 5 mm is very low (0.5%). This has important implications for the potential practice of "predicting, resecting, and discarding" diminutive colon polyps.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

BACKGROUND

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

OBJECTIVES

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

SEARCH METHODS

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

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

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

AUTHORS' CONCLUSIONS

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

Colonoscopy: basic principles and novel techniques

Colonoscopy is considered the 'gold standard' for detection and removal of premalignant lesions in the colon. However, studies suggest that colonoscopy is less protective for right-sided than for left-sided colorectal cancer. Optimizing the effectiveness of colonoscopy is a continuous process, and during the past decade several important quality indicators have been defined that can be used to measure the performance of colonoscopy and to identify areas for quality improvement. The quality of bowel preparation can be enhanced by split-dose regimens, which are superior to single-dose regimens. Cecal intubation rates should approximate 95% and can be optimized by good technique. In selected patients, specific devices can be used to facilitate cecal intubation. Adenoma detection rates should be monitored and exceed a minimum of 25% in men and 15% in women. To this aim, optimal withdrawal technique and adequate time for inspection are of utmost importance. Of all advanced imaging techniques, chromoendoscopy is the only technique with proven benefit for adenoma detection. Finally, the technique of polypectomy affects the number of complications as well as the success of completely removing a lesion. In this Review, we provide an overview of both standard and novel colonoscopy techniques and their impact on quality indicators.

Evolving techniques in colonoscopy

PURPOSE OF REVIEW

This review summarizes recent clinical studies of colonoscopy technique and new technologies.

RECENT FINDINGS

Water immersion reduces pain and sedation doses in unsedated and lightly sedated colonoscopy. Cap-fitted colonoscopy makes insertion faster and improves detection of lesions behind folds, but the latter effect is operator-dependent. A single controlled trial showed improved detection with the Third Eye Retroscope, but the two arms of the study were not controlled for withdrawal time. Chromoendoscopy increases detection of diminutive adenomas, but adds time to the colonoscopy procedure. Electronic chromoendoscopy methods (narrow band imaging, Fujinon Intelligent ChromoEndoscopy, i-scan, and autofluorescence) have been either unsuccessful in improving detection or require more study. However, these methods and several other methods (chromoendoscopy with magnification, confocal laser microscopy, and endocytoscopy) allow accurate real time determination of polyp histology.

SUMMARY

Water immersion is a clear advance in unsedated colonoscopy. Cap-fitted colonoscopy is a promising method for both practical and effective visualization of the proximal sides of haustral folds. Electronic chromoendoscopy has been largely ineffective at improving polyp detection, but is effective (as are confocal laser microscopy and endocytoscopy) for diagnosis of polyp histology.

An unmet medical need: advances in endoscopic imaging of colorectal neoplasia

Gastrointestinal cancer is a major public health problem worldwide. Detection of early neoplastic lesions in gastrointestinal tract is essential for cure, because prognosis and survival are related to the size and stage of malignant lesions. Endoscopic screening and treatment of polyps could prevent approximately 80% of colorectal cancer (CRC). However, white-light endoscopy is an imperfect technology since miss rates of up to 25% have been reported and polyps without malignant potential were treated without benefit but with additional costs and risks to the patient. There are several known "human" predictors of an inadequate colonoscopy. These include patient characteristics such as poor bowel preparation, female gender, or inpatient status. Skills of the endoscopists are also an important issue. Therefore, a variety of advanced technologies has been attempted to overcome these issues. These new endoscopic imaging techniques allow a more precise classification of mucosal alterations with selection of patients for invasive therapy or surveillance. Further, molecular and functional imaging techniques could identify novel targets for therapies and new prospects to access response to therapies. However, at the "end of the day" a better endoscopic approach for CRC screening and surveillance depends on a good bowel preparation, a trained endoscopist spending sufficient time on a detailed examination together with an advanced endoscope.

Proceedings of a preliminary workshop at Gastro 2009--narrow banding imaging in digestive endoscopy: clinical outcome of classification (Omed-Jges Educational Meeting held on 22 November, 2009)

This publication reports the proceedings of the preliminary meeting of the working party that met at Gastro 2009 during the World Congress in London. The purpose of the preliminary meeting was to consider the areas that require attention, to discuss some of the findings that have already been published and to agree on the way forward. Our reason for publishing these proceedings is to stimulate interest in this venture and to provide the opportunity for input from the endoscopy community worldwide. The next meeting of the working party will be at the JGES Society meeting in Aomori in April 2011 when we hope to prepare a preliminary classification. This will be presented for general discussion and debate at the International Congress of Endoscopy (ICE) in Los Angeles in September 2011.

Endoscopic trimodal imaging detects colonic neoplasia as well as standard video endoscopy

BACKGROUND & AIMS

Endoscopic trimodal imaging (ETMI) is a novel endoscopic technique that combines high-resolution endoscopy (HRE), autofluorescence imaging (AFI), and narrow-band imaging (NBI) that has only been studied in academic settings. We performed a randomized, controlled trial in a nonacademic setting to compare ETMI with standard video endoscopy (SVE) in the detection and differentiation of colorectal lesions.

METHODS

The study included 234 patients scheduled to receive colonoscopy who were randomly assigned to undergo a colonoscopy in tandem with either ETMI or SVE. In the ETMI group (n=118), first examination was performed using HRE, followed by AFI. In the other group, both examinations were performed using SVE (n=116). In the ETMI group, detected lesions were differentiated using AFI and NBI.

RESULTS

In the ETMI group, 87 adenomas were detected in the first examination (with HRE), and then 34 adenomas were detected during second inspection (with AFI). In the SVE group, 79 adenomas were detected during the first inspection, and then 33 adenomas were detected during the second inspection. Adenoma detection rates did not differ significantly between the 2 groups (ETMI: 1.03 vs SVE: 0.97, P=.360). The adenoma miss-rate was 29% for HRE and 28% for SVE. The sensitivity, specificity, and accuracy of NBI in differentiating adenomas from nonadenomatous lesions were 87%, 63%, and 75%, respectively; corresponding values for AFI were 90%, 37%, and 62%, respectively.

CONCLUSIONS

In a nonacademic setting, ETMI did not improve the detection rate for adenomas compared with SVE. NBI and AFI each differentiated colonic lesions with high levels of sensitivity but low levels of specificity.

The benefit of using narrow-band imaging systems for observation of capillary networks before determining of treatments for early colon cancer

INTRODUCTION

This study examined whether magnifying endoscopy with narrow-band Imaging observation could be useful selecting the appropriate treatment for early colon cancer.

PATIENTS AND METHODS

We analyzed 551 cases of colon tumors excised endoscopically or surgically, comprising 68 with large hyperplastic polyps, 25 traditional serrated adenomas, 141 tubular adenomas, 177 intramucosal cancers and 140 submucosal invasive (SM) cancers. We classified capillary network pattern into four types according to the degree of dilatation, irregularity and distribution of microcapillary features. These results were then compared with the histological findings.

RESULTS

The comparison of capillary pattern and histological features showed microcapillary networks by magnifying endoscopy with narrow-band imaging observation in intramucosal lesion or SM cancer with remnant neoplastic glands at the superficial layer.

CONCLUSIONS

The remaining microcapillary network was designed to maintain the architecture of neoplastic glands, even in the presence of subumucosal invasion. Consequently, loss of this network could correlate with depth of tumor invasion and histological reaction. Therefore, even if the tumor, remained of network was diagnosed to invade into SM layer, it should be checked up further examination by using magnifying endoscopy with crystal violet staining.

Advances in endoscopic visualization of colorectal polyps

AIM

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

METHOD

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

RESULTS

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

CONCLUSION

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

Imaging by Magnifying Endoscopy with NBI Implicates the Remnant Capillary Network As an Indication for Endoscopic Resection in Early Colon Cancer

Introduction. This study examined whether magnifying endoscopy with NBI observation (ME-NBI) could be useful selecting the appropriate treatment for submucosal invasive cancer (SM cancer). Patients and Methods. We analyzed 515 cases of colon tumors excised endoscopically or surgically. We classified capillary network pattern into four types according to the degree of dilatation, irregularity, and distribution of microcapillary features. Results. The comparison of capillary pattern and histological features revealed microcapillary networks by using confocal laser-scanning microscopy and ME-NBI in intramucosal lesion or SM cancer with remnant neoplastic glands at the superficial layer. In contrast, the network was absent in SM cancer with desmoplastic reactions, which invaded deeper into the submucosal layer. Conclusions. The remaining microcapillary network is designed to maintain the architecture of neoplastic glands. Consequently, loss of this network could correlate with depth of tumor invasion and desmoplastic reaction. Therefore, we can decide the appropriate treatment by using ME-NBI method.

Molecular imaging: interaction between basic and clinical science

One of the major proceedings in the field of gastrointestinal endoscopy has been the advent of molecular imaging, which possesses the potential to have a significant effect on the existing diagnostic and therapeutic paradigms. Molecular imaging encompasses different methods that enable the visualization of disease-specific morphologic or functional alterations of the mucosa based on the molecular signature of individual cells. This development has been made possible by advancements in basic science coupled with technological innovations in endoscopy, both facilitating the identification and characterization of mucosal lesions in vivo based on the lesions' molecular composition rather than their morphologic structure alone. Novel studies based on fluorescent antibody imaging pave the road toward clinical translation and give hope for improved diagnosis and targeted therapies in gastrointestinal diseases.

Enhanced mucosal imaging

PURPOSE OF REVIEW

The continued application of innovative imaging systems to endoscopic procedures has vastly improved the detection of indiscriminant tissue anomalies. This article describes the fundamental principles of these technologies and reviews the advances of each over the past 18 months, considering their utility in the diagnosis and surveillance of various gastrointestinal diseases.

RECENT FINDINGS

Through a combination of novel optics, processors and filters, real-time high-resolution contrast endoscopy provides increased visual data without greater procedure duration or difficulty. Optical contrast techniques incorporated into endoscopes, such as narrow band imaging (Olympus), i-Scan (Pentax), and Fujinon Intelligent Chromo Endoscopy, have become standard of care for many endoscopists. These technologies, as well as autofluorescence imaging, potentially improve detection of mucosal abnormalities, serving as 'red flag' tools for the evaluation of wide areas of mucosa. In addition, a number of promising devices allow virtual histology and in-vivo diagnosis, thereby directing biopsies and potentially guiding concurrent interventions. One such technology, confocal laser endomicroscopy, continues to establish its role in clinical practice. Because of inherent shortcomings affecting each modality's sensitivity and specificity, the coupling of various devices, as with endoscopic trimodal imaging, has shown great promise; however, most are not widely available and not definitively proven to be superior to more established techniques. Emerging technologies, including in-vivo molecular tagging, provide a powerful means of detecting disease without reliance on morphologic diagnostic criteria.

SUMMARY

Endoscopy continues to evolve from a field that previously allowed only macroscopic imaging dependent on subsequent pathology to one that allows real-time in-vivo diagnosis. Although the promise of enhanced endoscopic technologies seems limitless, practical and technological considerations slow their adoption into the standard of care.

Diagnostic accuracy of narrow-band imaging and pit pattern analysis significantly improved for less-experienced endoscopists after an expanded training program

BACKGROUND

Previous reports assessing diagnostic skill using narrow-band imaging (NBI) and pit pattern analysis for colorectal polyps involved only highly experienced endoscopists.

OBJECTIVE

To evaluate diagnostic skills of less-experienced endoscopists (LEE group) for differentiation of diminutive colorectal polyps by using NBI and pit pattern analysis with and without magnification after an expanded training program.

DESIGN

Prospective study.

PATIENTS

This study involved 32 patients with 44 colorectal polyps (27 adenomas and 17 hyperplastic polyps) of < or =5 mm that were identified and analyzed by using conventional colonoscopy as well as non-magnification and magnification NBI and chromoendoscopy followed by endoscopic removal for histopathological analysis.

INTERVENTION

Before a training course, 220 endoscopic images were distributed in randomized order to residents with no prior endoscopy experience (NEE group) and to the LEE group, who had performed colonoscopies for more than 5 years but had never used NBI. The 220 images were also distributed to highly experienced endoscopists (HEE group) who had routinely used NBI for more than 5 years. The images were distributed to the NEE and LEE groups again after a training class. Magnification NBI and chromoendoscopy images were assessed by using the Sano and Kudo classification systems, respectively.

MAIN OUTCOME MEASUREMENTS

Diagnostic accuracy and interobserver agreement for each endoscopic modality in each group.

RESULTS

Diagnostic accuracy was significantly higher, and kappa (kappa) values improved in the LEE group for NBI with high magnification after expanded training. Diagnostic accuracy and kappa values when using high-magnification NBI were highest among endoscopic techniques for the LEE group after such training and the HEE group (accuracy 90% vs 93%; kappa = 0.79 vs 0.85, respectively).

LIMITATIONS

Study involved only polyps of < or =5 mm.

CONCLUSION

Using high-magnification NBI increased the differential diagnostic skill of the LEE group after expanded training so that it was equivalent to that of the HEE group.

Advances in endoscopic imaging of colorectal neoplasia

Colon cancer screening is arguably the most important activity performed by gastroenterologists. Recent decreases in rates of death from colorectal cancer indicate that screening methods such as colonoscopy have a positive impact. There is still room for improvement, however, particularly in prevention of right-sided colon cancer. Practice issues, such as making colonoscopy more comfortable, safer, and less costly, are keys to continued success in cancer prevention. Colonoscopy techniques, technologies, and quality control measures have advanced to improve detection, classification, and removal of early neoplasias. In particular, slow, careful inspection of the colon by gastroenterologists who have been trained in lesion recognition has improved rates of detection of polypoid and flat neoplasias. Image enhancement methods such as chromoendoscopy have greatly improved neoplasia detection in patients with chronic colitis, but are not widely used because they are perceived as inconvenient. More convenient methods, such as "digital" chromoendoscopy, show promise but have had mixed results. Ultra-high magnification systems, including optical magnification and confocal endomicroscopy, can be used during the colonoscopy examination to evaluate small polyps, allowing physicians to make immediate diagnoses and decisions about whether to remove polyps. In patients with inflammatory bowel disease, improved imaging techniques could eliminate the needs for analysis of randomly selected biopsy samples and resection of all (neoplastic and non-neoplastic) polyps. It is important to maintain high standards of quality for colonoscopy examination, detection, and removal of high-risk lesions, as well as to make colon cancer screening more widely accepted and affordable for the entire at-risk population.

Narrow Band Imaging and Autofluorescence Imaging for the Detection and Optical Diagnosis of Colorectal Polyps

Colorectal cancer is the most common cancer in Singapore and polyps which are detected during screening colonoscopy are routinely removed. Conventional white light colonoscopy has a substantial miss-rate for polyps and limited accuracy in differentiating neoplastic from non-neoplastic polyps. Dye-based chromoendoscopy and more recent equipment-based image enhanced endoscopic techniques such as narrow-band imaging (NBI) and autofluorescence imaging (AFI) are promising tools to improve polyp detection and optical diagnosis. Current evidence suggests that NBI may not be superior compared to high definition white-light for polyp detection, but it achieves excellent accuracy in polyp characterisation, approaching that of histopathology. AFI is a wide area scanning modality which functions as a red-flag technique to improve polyp detection, although the evidence is still evolving. The ability to accurately characterise polyps with NBI and AFI will guide the management of polyps and in some cases, avoid unnecessary polypectomy and routine histopathology. This has potential to reduce associated costs and risks of polypectomy, and improves on overall efficiency of screening colonoscopy. The review will discuss the technology, current evidence and the issues relevant to the role of NBI and AFI for the detection and optical diagnosis of polyps in colorectal cancer screening.