Acetic acid-guided biopsies after magnifying endoscopy compared with random biopsies in the detection of Barrett's esophagus: a prospective randomized trial with crossover design

Can Chromoendoscopy Improve the Early Diagnosis of Gastric Carcinoma in Dogs?

Simple Summary

Currently, canine gastric carcinoma is mainly diagnosed in its late, incurable phase, and strategies for early diagnosis are lacking. In human medicine, chromoendoscopic (CE) methods such as staining the gastric mucosal surface with indigo carmine (IC), and narrow band imaging (NBI), have improved the diagnosis of precancerous gastric mucosal changes and early gastric carcinoma. This study aimed at investigating whether IC-CE and NBI-CE can improve the diagnostic yield of endoscopy in dogs. Belgian Shepherd dogs are predisposed to gastric carcinoma; thus, 30 dogs of the breed served as the study population. As a result, the study revealed that especially the combination of standard white light endoscopy (WLE) with NBI-CE allows better recognition of gastric mucosal structural changes than WLE alone. However, CE assessment templates used to predict the type of mucosal change in humans were not applicable in dogs. The value of the study lies in providing evidence that CE can improve the diagnosis of precancerous changes and early gastric carcinoma in dogs. However, current image assessment templates from human medicine need major adjustments to comprehend canine gastric mucosal conditions.

Abstract

Chromoendoscopy has improved the early diagnosis of gastric cancer in humans but its usefulness in dogs is unknown. This study aimed at assessing whether adding narrow band imaging (NBI) or indigo carmine (IC) chromoendoscopy (CE) can improve the diagnostic yield of standard white light endoscopy (WLE). We compared the real-time findings of canine WLE, NBI-CE, and IC-CE and corresponding histology reports with endoscopic mucosal pattern assessment templates used in human medicine. Belgian Shepherd dogs are predisposed to gastric carcinoma. Therefore, 30 dogs of this breed served as the study population. According to histology, 17/30 dogs had mucosal changes (mucous metaplasia, glandular dysplasia, and gastric carcinoma). Diagnostic yield was best when targeted biopsies were taken with WLE and NBI-CE combined (15/17 cases). WLE alone positively identified only 8/17 cases and missed a gastric carcinoma in 3/6 cases. CE assessment templates based on macroscopic mucosal patterns, broadly used in human medicine, were not readily applicable in dogs. In conclusion, the study provides evidence that using CE in dogs has the potential to improve the diagnosis of precancerous gastric mucosal pathology and early gastric carcinoma. However, current image assessment templates from human medicine need major adjustments to the patterns of canine gastric mucosa.

Endoscopic Management of Esophageal Cancer

Advances in technology and improved understanding of the pathobiology of esophageal cancer have allowed endoscopy to serve a growing role in the management of this disease. Precursor lesions can be detected using enhanced diagnostic modalities and eradicated with ablation therapy. Furthermore, evolution in endoscopic resection has provided larger specimens for improved diagnostic accuracy and offer potential for cure of early esophageal cancer. In patients with advanced esophageal cancer, endoluminal therapy can improve symptom burden and provide therapeutic options for complications such as leaks, perforations, and fistulas. The purpose of this review article is to highlight the role of endoscopy in the diagnosis, treatment, and palliation of esophageal cancer.

Enhancing the Detection of Barrett Esophagus

In Western countries, the incidence of esophageal adenocarcinoma has increased rapidly in parallel with its premalignant condition, Barrett esophagus (BE). Unlike colonoscopy, endoscopic screening for BE is not currently recommended for all patients; however, surveillance endoscopy is advocated for patients with established BE. Novel imaging and sampling techniques have been developed and investigated for the purpose of improving the detection of Barrett esophagus, dysplasia, and neoplasia. This article discusses several screening and surveillance techniques, including Seattle protocol, chromoendoscopy, electronic chromoendoscopy, wide area transepithelial sampling with 3-dimensional analysis, nonendoscopic sampling devices, and transnasal endoscopy.

Impact of advanced endoscopic imaging on Barrett's esophagus in daily clinical practice

BACKGROUND AND AIMS

Several advanced imaging techniques have been proposed to improve the visualization of dysplastic regions within Barrett's epithelium, with some evidence for the use of narrow-band imaging (NBI) and acetic acid chromoendoscopy (AAC).

METHODS

We retrospectively analyzed consecutive cases of Barrett's esophagus, diagnosed using white-light endoscopy and confirmed histologically by the presence of intestinal metaplasia, between April 2007 and April 2010 in a large community hospital. A change in practice was then instituted, whereby a Barrett's team consisting of specialist endoscopists was formed in an attempt to standardize and improve the quality of surveillance. Barrett's epithelium was inspected with both white-light imaging and NBI in all patients. Where the length of Barrett's epithelium was 3 cm or more, AAC was also used. One and a half percent acetic acid was sprayed onto the Barrett's segment and loss of aceto-whitening observed after a 2-minute period. Any abnormal areas noted during advanced imaging underwent target biopsy sampling. We subsequently compared the dysplasia detection rate in Barrett's epithelium identified between April 2011 and April 2014 after these changes. Observed differences between the cohorts were analyzed with the Fisher exact test and the Student t test.

RESULTS

From 2007 to 2010 Barrett's esophagus was identified during 560 gastroscopies in 392 individual patients. The mean maximal Barrett's esophagus recorded length was 4.4 cm (range, 1-10), with an average of 4.7 esophageal biopsy specimens taken per endoscopy. In comparison, from 2011 to 2014 Barrett's esophagus was identified during 856 endoscopies in 630 patients. From 2011 to 2014 the Barrett's team performed 85% of all procedures using the aforementioned techniques. The mean maximal Barrett's esophagus length was 3.8 cm (range, 1-16), with an increased average of 5.8 biopsy specimens per endoscopy taken (P < .01). Both cohorts were comparable in age and gender distribution. Our data demonstrated no significant difference in the relative frequencies of occurrence of dysplasia detected between both cohorts of patients. From 2007 to 2010 dysplasia was detected in 11.0% (n = 43) of patients. This consisted of low-grade dysplasia in 7.7% of patients and high-grade dysplasia or cancer 3.3%. From 2011 to 2014 this compared with dysplasia in 11.3% (n = 71) of patients, with low-grade dysplasia in 9.4% and high-grade dysplasia or cancer in 1.9%.

CONCLUSIONS

Our data show that the use of NBI and AAC in the imaging of Barrett's esophagus did not result in an increased detection rate of dysplasia in routine clinical practice. These findings concur with the recommendations of existing Barrett's esophagus surveillance guidelines, which advocate the continued use of quadratic biopsy sampling within general surveillance programs.

A guide to multimodal endoscopy imaging for gastrointestinal malignancy - an early indicator

Multimodality imaging is an essential aspect of endoscopic surveillance for the detection of neoplastic lesions, such as dysplasia or intramucosal cancer, because it improves the efficacy of endoscopic surveillance and therapeutic procedures in the gastrointestinal tract. This approach reveals mucosal abnormalities that cannot be detected by standard endoscopy. Currently, these imaging techniques are divided into those for primary detection and those for targeted imaging and characterization, the latter being used to visualize areas of interest in detail and permit histological evaluation. This Review outlines the use of virtual chromoendoscopy, narrow-band imaging, autofluorescence imaging, optical coherence tomography, confocal endomicroscopy and volumetric laser endomicroscopy as new imaging techniques for diagnostic investigation of the gastrointestinal tract. Insights into use of multimodal endoscopic imaging for early disease detection, in particular for pre-malignant lesions, in the oesophagus, stomach and colon are described.

Review: Surveillance of patients with Barrett oesophagus

There has been a rapid increase in the incidence of oesophageal adenocarcinoma in most Western countries over the past thirty years. Barrett's oesophagus (BE) is a common premalignant lesion of oesophageal adenocarcinoma, although the risk of developing cancer in BE remains low. Therefore, screening is not recommended in the general population. Surveillance of BE is recommended to detect high grade dysplasia or carcinoma in an early stage, although there is no clear evidence that surveillance leads to a reduced mortality. This review discusses the several screening and surveillance techniques, including chromoendoscopy, narrow band imaging, autofluorescence imaging and confocal laser endomicroscopy, pointing out the areas that are well established as well as the new techniques that require more research.

Barrett’s esophagus in 2016: From pathophysiology to treatment

Esophageal complications caused by gastroesophageal reflux disease (GERD) include reflux esophagitis and Barrett’s esophagus (BE). BE is a premalignant condition with an increased risk of developing esophageal adenocarcinoma (EAC). The carcinogenic sequence may progress through several steps, from normal esophageal mucosa through BE to EAC. A recent advent of functional esophageal testing (particularly multichannel intraluminal impedance and pH monitoring) has helped to improve our knowledge about GERD pathophysiology, including its complications. Those findings (when properly confirmed) might help to predict BE neoplastic progression. Over the last few decades, the incidence of EAC has continued to rise in Western populations. However, only a minority of BE patients develop EAC, opening the debate regarding the cost-effectiveness of current screening/surveillance strategies. Thus, major efforts in clinical and research practice are focused on new methods for optimal risk assessment that can stratify BE patients at low or high risk of developing EAC, which should improve the cost effectiveness of screening/surveillance programs and consequently significantly affect health-care costs. Furthermore, the area of BE therapeutic management is rapidly evolving. Endoscopic eradication therapies have been shown to be effective, and new therapeutic options for BE and EAC have emerged. The aim of the present review article is to highlight the status of screening/surveillance programs and the current progress of BE therapy. Moreover, we discuss the recent introduction of novel esophageal pathophysiological exams that have improved the knowledge of the mechanisms linking GERD to BE.

ASGE Technology Committee systematic review and meta-analysis assessing the ASGE Preservation and Incorporation of Valuable Endoscopic Innovations thresholds for adopting real-time imaging-assisted endoscopic targeted biopsy during endoscopic surveillance of Barrett's esophagus

BACKGROUND AND AIMS

Endoscopic real-time imaging of Barrett's esophagus (BE) with advanced imaging technologies enables targeted biopsies and may eliminate the need for random biopsies to detect dysplasia during endoscopic surveillance of BE. This systematic review and meta-analysis was performed by the American Society for Gastrointestinal Endoscopy (ASGE) Technology Committee to specifically assess whether acceptable performance thresholds outlined by the ASGE Preservation and Incorporation of Valuable Endoscopic Innovations (PIVI) document for clinical adoption of these technologies have been met.

METHODS

We conducted meta-analyses calculating the pooled sensitivity, negative predictive value (NPV), and specificity for chromoendoscopy by using acetic acid and methylene blue, electronic chromoendoscopy by using narrow-band imaging, and confocal laser endomicroscopy (CLE) for the detection of dysplasia. Random effects meta-analysis models were used. Statistical heterogeneity was evaluated by means of I(2) statistics.

RESULTS

The pooled sensitivity, NPV, and specificity for acetic acid chromoendoscopy were 96.6% (95% confidence interval [CI], 95-98), 98.3% (95% CI, 94.8-99.4), and 84.6% (95% CI, 68.5-93.2), respectively. The pooled sensitivity, NPV, and specificity for electronic chromoendoscopy by using narrow-band imaging were 94.2% (95% CI, 82.6-98.2), 97.5% (95% CI, 95.1-98.7), and 94.4% (95% CI, 80.5-98.6), respectively. The pooled sensitivity, NPV, and specificity for endoscope-based CLE were 90.4% (95% CI, 71.9-97.2), 98.3% (95% CI, 94.2-99.5), and 92.7% (95% CI, 87-96), respectively.

CONCLUSIONS

Our meta-analysis indicates that targeted biopsies with acetic acid chromoendoscopy, electronic chromoendoscopy by using narrow-band imaging, and endoscope-based CLE meet the thresholds set by the ASGE PIVI, at least when performed by endoscopists with expertise in advanced imaging techniques. The ASGE Technology Committee therefore endorses using these advanced imaging modalities to guide targeted biopsies for the detection of dysplasia during surveillance of patients with previously nondysplastic BE, thereby replacing the currently used random biopsy protocols.

Endoscopic imaging of Barrett’s esophagus

The incidence of esophageal adenocarcinoma (EAC) has dramatically increased in the United States as well as Western European countries. The majority of esophageal adenocarcinomas arise from a backdrop of Barrett’s esophagus (BE), a premalignant lesion that can lead to dysplasia and cancer. Because of the increased risk of EAC, GI society guidelines recommend endoscopic surveillance of patients with BE. The emphasis on early detection of dysplasia in BE through surveillance endoscopy has led to the development of advanced endoscopic imaging technologies. These techniques have the potential to both improve mucosal visualization and characterization and to detect small mucosal abnormalities which are difficult to identify with standard endoscopy. This review summarizes the advanced imaging technologies used in evaluation of BE.

Acetic acid chromoendoscopy for the diagnosis of early neoplasia and specialized intestinal metaplasia in Barrett's esophagus: a meta-analysis

BACKGROUND AND AIMS

Barrett's esophagus (BE) surveillance with random biopsies is time-consuming, invasive, and can lead to sampling error. Acetic acid chromoendoscopy (AAC) with targeted biopsies has been proposed as an effective alternative. The aim of this study was to assess the diagnostic accuracy of AAC for the detection of early neoplasia (high-grade dysplasia [HGD] or early cancer [EC]) and specialized intestinal metaplasia (SIM) in patients with BE.

METHODS

We performed a meta-analysis of all primary studies that compared AAC-based diagnoses (index test) with histopathology as the reference standard. The data were extracted on a per-patient, per-area, and per-procedure basis whenever available.

RESULTS

Thirteen prospective studies met the inclusion criteria. For the diagnosis of HGD/EC, the pooled sensitivity, specificity, positive likelihood ratio (LR+), and negative likelihood ratio (LR-) for all included studies (9 studies, 1379 patients) were 0.92 (95% confidence interval [CI], 0.83-0.97), 0.96 (95% CI, 0.85-0.99), 25.0 (95% CI, 5.9-105.3), and 0.08 (95% CI, 0.04-0.18), respectively. Results were not significantly different when considering only studies with a per-patient analysis. For the characterization of SIM, the pooled sensitivity, specificity, LR+, and LR- for all the included studies (8 studies, 516 patients) were 0.96 (95% CI, 0.83-0.99), 0.69 (95% CI, 0.54-0.81), 3.0 (95% CI, 2.0-4.7), and 0.06 (95% CI, 0.01-0.26), respectively. No significant sources of heterogeneity were identified on subgroup analysis.

CONCLUSION

AAC has an overall high diagnostic accuracy for detecting HGD/EC in patients with BE. For SIM characterization, AAC sensitivity is very high but has poor specificity, suggesting that histological confirmation is necessary when AAC is positive.

Endoscopic modalities for the diagnosis of Barrett's oesophagus

Barrett's oesophagus is a pre-malignant condition associated with the development of oesophageal adenocarcinoma. Currently white light endoscopy and biopsy is the mainstay diagnostic tool. Yet this approach is troubled by issues related to cumbersome biopsy sampling, biopsy sampling errors and cost. Therefore in order to overcome such adversity, there needs to be evolutionary advancement in terms of diagnosis, which should address these concerns and ideally enhance risk stratification in order to provide timely management in real time. This review highlights the current endoscopic tools aimed to enhance the diagnosis of Barrett's oesophagus and its subsequent progression.

Red flag imaging in Barrett's esophagus: does it help to find the needle in the haystack?

Esophageal Adenocarcinoma (EAC) has suffered a sharp increase on its incidence for the last decades, and it is associated with a poor prognosis. Barrett's Esophagus (BE) is the most important identifiable risk factor for the progression to esophageal adenocarcinoma. The key to prevent and provide a curative treatment of esophageal adenocarcinoma is the detection and eradication of early neoplasia in patients with esophagus. Endoscopic surveillance is evolving from a blind or random four quadrant biopsies protocol (Seattle protocol) to a more targeted approach. A detailed white light examination with high-resolution endoscopy is the cornerstone for recognition of early neoplastic lesions in BE. Additional imaging modalities may enhance targeting of lesions or provide more information at a focused level. There are emerging data that some of these new modalities can increase the yield of detecting dysplasia, although its routine use has yet to be validated.

The role of acetic acid in the management of Barrett's oesophagus

Barrett's oesophagus is of significant importance due to its premalignant potential. Acetic acid chromoendoscopy is a simple technique that can be used with any endoscope system. It has been utilised for the identification of Barrett's intestinal metaplasia; and more importantly, for the localisation of early neoplasia within Barrett's, which is often focal, subtle and very easy to miss by random quadrantic biopsies alone. Acetic acid is routinely utilised in specialised centres and its use is expanding. This article examines the evidence base behind acetic acid chromoendoscopy and looks at where further research needs to be directed.

Endoscopic imaging in Barrett's esophagus

Barrett's esophagus is the only known precursor that predisposes patients to the development of esophageal adenocarcinoma. The current recommended surveillance method is targeted biopsies of any abnormalities followed by random four-quadrant biopsies every 2 cm using standard white light endoscopy. Compliance with this and sampling error are two of the biggest problems. Several novel imaging technologies have been developed to aid the diagnosis of early neoplasia in Barrett's esophagus. There are emerging data that some of these new modalities can increase the yield of detecting dysplasia. This review will discuss some of the present available techniques and technologies including chromoendoscopy, narrow-band imaging, autofluorescence imaging, optical coherence tomography, confocal endomicroscopy and endocytoscopy. Based on the current evidence, these imaging modalities appear to be promising as adjunctive tools to white light endoscopy. A few of them, nevertheless, remain experimental due to expense, lack of expertise, generalizability as well as reproducibility of results.

Endoscopic surveillance of gastrointestinal premalignant lesions: current knowledge and future directions

PURPOSE OF REVIEW

Provide an evidence-based resource for the surveillance of gastrointestinal premalignant lesions, focusing on the scientific articles reported recently.

RECENT FINDINGS

No randomized controlled clinical trials exist to definitively support the efficacy of surveillance programs for Barrett's esophagus and gastric intestinal metaplasia. However, surveillance of these premalignant lesions is recommended by some of the leading organizations. To optimize the usefulness of surveillance programs, targeting high-risk patients might maximize its benefits. A Barrett's esophagus segment of at least 3 cm and evidence of intestinal metaplasia can help stratify those patients at highest risk for progression to esophageal adenocarcinoma. The location, extent, and severity of intestinal metaplasia are indicators of risk of developing gastric cancer. Patients with extensive intestinal metaplasia should be offered endoscopic surveillance. Quality in the baseline colonoscopy is crucial to decrease the risk of interval colorectal cancers. The importance of serrated polyps, as well as their surveillance intervals, is emphasized.

SUMMARY

To optimize the usefulness of surveillance programs, targeting high-risk patients might maximize its benefits. Future research is needed to design more effective surveillance strategies. Recently, emerging imaging techniques hold promise for improving sensitivity of endoscopic surveillance of premalignant conditions in the gastrointestinal tract.

Barrett's esophagus and cancer risk: how research advances can impact clinical practice

Barrett’s esophagus (BE) is the only known precursor to esophageal adenocarcinoma (EAC), whose incidence has increased sharply in the last 4 decades. The annual conversion rate of BE to cancer is significant, but small. The identification of patients at a higher risk of cancer therefore poses a clinical conundrum. Currently, endoscopic surveillance is recommended in BE patients, with the aim of diagnosing either dysplasia or cancer at early stages, both of which are curable with minimally invasive endoscopic techniques. There is a large variation in clinical practice for endoscopic surveillance, and dysplasia as a marker of increased risk is affected by sampling error and high interobserver variability. Screening programs have not yet been formally accepted, mainly due to the economic burden that would be generated by upper gastrointestinal endoscopy. Screening programs have not yet been formally accepted, mainly due to the economic burden that would be generated by widespread indication to upper gastrointestinal endoscopy. In fact, it is currently difficult to formulate an accurate algorithm to confidently target the population at risk, based on the known clinical risk factors for BE and EAC. This review will focus on the clinical and molecular factors that are involved in the development of BE and its conversion to cancer and on how increased knowledge in these areas can improve the clinical management of the disease.

Advanced imaging technologies for the detection of dysplasia and early cancer in barrett esophagus

Advanced esophageal adenocarcinomas arising from Barrett esophagus (BE) are tumors with an increasing incidence and poor prognosis. The aim of endoscopic surveillance of BE is to detect dysplasia, particularly high-grade dysplasia and intramucosal cancers that can subsequently be treated endoscopically before progression to invasive cancer with lymph node metastases. Current surveillance practice standards require the collection of random 4-quadrant biopsy specimens over every 1 to 2 cm of BE (Seattle protocol) to detect dysplasia with the assistance of white light endoscopy, in addition to performing targeted biopsies of recognizable lesions. This approach is labor-intensive but should currently be considered state of the art. Chromoendoscopy, virtual chromoendoscopy (e.g., narrow band imaging), and confocal laser endomicroscopy, in addition to high-definition standard endoscopy, might increase the diagnostic yield for the detection of dysplastic lesions. Until these modalities have been demonstrated to enhance efficiency or cost effectiveness, the standard protocol will remain careful examination using conventional off the shelf high-resolution endoscopes, combined with as longer inspection time which is associated with increased detection of dysplasia.

Acetic acid compared with i-scan imaging for detecting Barrett's esophagus: a randomized, comparative trial

BACKGROUND

Traditional surveillance in patients with Barrett's esophagus (BE) has relied on random biopsies. Targeted biopsies that use advanced imaging modalities may significantly improve detection of specialized columnar epithelium (SCE).

OBJECTIVE

We compared the efficacy of targeted biopsies that used i-scan or acetic acid to random biopsies in the detection of SCE.

DESIGN

Patients with visible columnar lined epithelium or known BE were randomized at a 1:1 ratio to undergo acetic acid application or i-scan with targeted biopsies.

SETTING

Targeted biopsies were performed based on surface architecture according to the Guelrud classification followed by 4-quadrant biopsies.

PATIENTS

A total of 95 patients were randomized.

INTERVENTION

A total of 46 patients underwent acetic acid staining, and 49 underwent i-scan imaging. Random biopsies were performed in 86 patients.

MAIN OUTCOME MEASUREMENTS

The primary outcome was the yield of SCE as confirmed by histologic assessment.

RESULTS

The diagnostic yield for SCE was significantly higher with targeted biopsies than with random biopsies in both groups combined (63% vs 24%; P = .0001). The yield of targeted biopsies was significantly greater with both i-scan (66% vs 21%; P = .009) and acetic acid (57% vs 26%; P = .012) technologies and did not differ between these groups. The accuracy for predicting SCE was 96% (k = .92) for i-scan and 86% (k = .70) for acetic acid analysis.

LIMITATIONS

No dysplastic lesions were found.

CONCLUSION

The i-scan or acetic acid-guided biopsies have a significantly higher diagnostic yield for identifying SCE, with significantly fewer biopsies, as compared with a protocol of random biopsies. Acetic acid and i-scan showed comparable results diagnosing SCE in our study. (

CLINICAL TRIAL REGISTRATION NUMBER

NCT01442506.).

British Society of Gastroenterology guidelines on the diagnosis and management of Barrett's oesophagus

These guidelines provide a practical and evidence-based resource for the management of patients with Barrett's oesophagus and related early neoplasia. The Appraisal of Guidelines for Research and Evaluation (AGREE II) instrument was followed to provide a methodological strategy for the guideline development. A systematic review of the literature was performed for English language articles published up until December 2012 in order to address controversial issues in Barrett's oesophagus including definition, screening and diagnosis, surveillance, pathological grading for dysplasia, management of dysplasia, and early cancer including training requirements. The rigour and quality of the studies was evaluated using the SIGN checklist system. Recommendations on each topic were scored by each author using a five-tier system (A+, strong agreement, to D+, strongly disagree). Statements that failed to reach substantial agreement among authors, defined as >80% agreement (A or A+), were revisited and modified until substantial agreement (>80%) was reached. In formulating these guidelines, we took into consideration benefits and risks for the population and national health system, as well as patient perspectives. For the first time, we have suggested stratification of patients according to their estimated cancer risk based on clinical and histopathological criteria. In order to improve communication between clinicians, we recommend the use of minimum datasets for reporting endoscopic and pathological findings. We advocate endoscopic therapy for high-grade dysplasia and early cancer, which should be performed in high-volume centres. We hope that these guidelines will standardise and improve management for patients with Barrett's oesophagus and related neoplasia.

Endoscopic mucosal imaging of gastrointestinal neoplasia in 2013

The holy grail of gastrointestinal endoscopy consists of the detection, in vivo characterization, and endoscopic removal of early or premalignant mucosal lesions. While our ability to achieve this goal has improved substantially since the development of the modern video-endoscope, inadequate visual inspection, errors of interpretation, and lesion subtlety all contribute to the continued suboptimal detection and assessment of early neoplasia. A myriad of new technologies has thus emerged that may help resolve these shortcomings; high magnification endoscopes, as well as the techniques of dye-based and virtual chromoendoscopy, are now widely available, while confocal laser endomicroscopy and endocystoscopy, optical coherence tomography, and autofluorescence imaging are generally applicable only in a research setting. Such technologies can be broadly categorized according to whether they potentially afford endoscopists improved detection, or real-time characterization, of mucosal lesions. Enhanced detection of otherwise "invisible" lesions, such as a flat area of intramucosal adenocarcinoma within Barrett's esophagus, carries the potential of an endoscopic cure prior to the development into a more advanced or metastatic disease. The ability to characterize a lesion to achieve an in vivo diagnosis, such as a colonic polyp, potentially affords endoscopists the ability to decide which lesions require removal and which can be safely left behind or discarded without histological assessment. Furthermore targeted biopsies, such as in the surveillance of chronic colitis, may prove to be more accurate and efficacious than the current protocol of random biopsies. An important caveat in the discussion of developing technologies in early cancer detection is the fundamental importance of a health-care system that promotes screening programs to recruit at-risk individuals. The ideal tool to optimize the use of endoscopy in population screening would be a panel of reliable biomarkers (blood, stool, or urine) that could effectively select a high-risk group, thus reducing the indiscriminate use of an expensive technology. The following review summarizes the current endoscopic imaging techniques available, and in development, for the early identification of gastrointestinal neoplasia.

What is the role of endoscopy and oesophageal biopsies in the management of GERD?

Gastroesophageal reflux disease (GERD) is a diagnosis applicable to "all individuals who are exposed to the risk of physical complications from gastroesophageal reflux, or who experience clinically significant impairment of health related well being (quality of life) due to reflux related symptoms, after adequate reassurance of the benign nature of their symptoms". It remains, predominantly, a symptom-based diagnosis, confirmed clinically by a response to acid suppression therapy although it is accompanied by demonstrable increases in acid exposure on esophageal pH-metry and by endoscopic and histological changes. Standard white light endoscopy permits diagnosis of erosive reflux disease (ERD) which, if present, should be graded for severity using the Los Angeles classification system. However, the role of endoscopy in clinical practice is, primarily, to evaluate patients with persistent symptoms, despite medical therapy, or to investigate alarm features and exclude complications such as Barrett' oesophagus which should be assessed using the Prague C & M criteria. Newer endoscopic techniques allow detection of 'minimal change' GERD lesions and Barrett's oesophagus-associated dysplastic or neoplastic lesions; however, none of the newer techniques has been validated for routine clinical practice. There is an increasing recognition that histology in GERD may provide useful diagnostic information, in part to exclude other lesions, such as eosinophilic oesophagitis, intestinal metaplasia and dysplasia or malignancy and, in part, to identify changes, such as basal cell hyperplasia, papillary elongation and, most recently, dilated intercellular spaces, that are consistent with GERD. However, more widespread incorporation of histology into the clinical management of GERD will require a standardized biopsy protocol and efforts to minimise interobserver differences in the identification of GERD-related histological changes.

Screening for precancerous lesions of upper gastrointestinal tract: from the endoscopists' viewpoint

Upper gastrointestinal tract cancers are one of the most important leading causes of cancer death worldwide. Diagnosis at late stages always brings about poor outcome of these malignancies. The early detection of precancerous or early cancerous lesions of gastrointestinal tract is therefore of utmost importance to improve the overall outcome and maintain a good quality of life of patients. The desire of endoscopists to visualize the invisibles under conventional white-light endoscopy has accelerated the advancements in endoscopy technologies. Nowadays, image-enhanced endoscopy which utilizes optical- or dye-based contrasting techniques has been widely applied in endoscopic screening program of gastrointestinal tract malignancies. These contrasting endoscopic technologies not only improve the visualization of early foci missed by conventional endoscopy, but also gain the insight of histopathology and tumor invasiveness, that is so-called optical biopsy. Here, we will review the application of advanced endoscopy technique in screening program of upper gastrointestinal tract cancers.

Longer inspection time is associated with increased detection of high-grade dysplasia and esophageal adenocarcinoma in Barrett's esophagus

BACKGROUND

Current guidelines recommend that endoscopic surveillance of Barrett's esophagus (BE) be performed by using a strict biopsy protocol. However, novel methods to improve BE surveillance are still needed.

OBJECTIVE

To evaluate the impact of Barrett's inspection time (BIT) on yield of surveillance.

DESIGN

Post hoc analysis of data obtained from a clinical trial.

SETTING

Five tertiary referral centers.

PATIENTS

Patients undergoing BE surveillance.

INTERVENTIONS

Coordinators prospectively recorded the time spent inspecting the BE mucosa with a stopwatch.

MAIN OUTCOME MEASUREMENTS

Endoscopically suspicious lesions, high-grade dysplasia (HGD)/esophageal adenocarcinoma (EAC).

RESULTS

A total of 112 patients underwent endoscopic surveillance by 11 individual endoscopists. Patients with longer BITs were more likely to have an endoscopically suspicious lesion (P < .001) and more endoscopically suspicious lesions (P = .0001) and receive a diagnosis of HGD/EAC (P = .001). There was a direct correlation between the endoscopist's mean BIT per centimeter of BE and the detection of patients with HGD/EAC (ρ = .63, P = .03). Endoscopists who had an average BIT longer than 1 minute per centimeter of BE detected more patients with endoscopically suspicious lesions (54.2% vs 13.3%, P = .04), and there was a trend toward a higher detection rate of HGD/EAC (40.2% vs 6.7%, P = .06).

LIMITATIONS

Post hoc analysis of an enriched study population and experienced endoscopists at tertiary referral centers.

CONCLUSIONS

Longer time spent inspecting the BE segment is associated with the increased detection of HGD/EAC. Taking additional time to perform a thorough examination of the BE mucosa may serve as an easy and widely available method to improve the yield of BE surveillance.

Confocal endomicroscopy (CEM) improves efficiency of Barrett surveillance

BACKGROUND

Endoscopists with extensive experience with confocal endomicroscopy (CEM) have demonstrated that this technology is useful for Barrett's esophagus (BE) surveillance. However, data on endoscopists with minimal experience with this technique are limited.

HYPOTHESIS

For BE surveillance, an endoscopist with minimal experience in CEM-guided biopsy would achieve a similar diagnostic yield with fewer biopsies when compared to the random 4-quadrant biopsy protocol.

OBJECTIVE

To compare the diagnostic yields of CEM-guided biopsy technique with the random 4-quadrant biopsy protocol.

DESIGN

Randomized controlled trial.

SETTING

Tertiary care center.

PATIENTS

Patients with BE.

METHODS

Out of 18 patients who underwent routine BE surveillance, 11 and 7 were randomly assigned to group A (CEM-guided) and to group B (random 4-quadrant biopsy), respectively. The pathologists were blinded to all clinical information.

RESULTS

Mean length of endoscopic Barrett was similar in both groups, (5.1 vs. 6.3 cm, p=0.51). The diagnostic yields for detecting SIM (63.6% vs. 59.5%, p=0.5), low grade dysplasia (11. 6% vs. 11.2%, p=NS), high grade dysplasia (10.1% vs. 11.5%, p=0.88). Although the total number of individual mucosal biopsy performed were 52% lower in the CEM group (129 vs. 269), the overall diagnostic yield (85.3% vs. 82.2%, p=0.53) was similar in both groups.

LIMITATIONS

Small sample size.

CONCLUSIONS

For BE surveillance, limited data suggested that endoscopists with minimal experience in CEM can effective use this technology for "smart" biopsy to decrease the need for intense tissue sampling but without lowering the diagnostic yield in detecting dysplasia.

Advances in endoscopic diagnosis of early esophageal cancer

Esophageal cancer is one of the most common malignancies in China. The prognosis of esophageal carcinoma is closely related to the stage of the disease at the time of detection. Patients with early lesions have an excellent prognosis, whereas those with more advanced stages of the disease usually have a poor prognosis. Therefore, the early detection of these lesions is of the greatest importance for treatment. Recently, many endoscopic methods have been developed, such as fluorescence endoscopy, confocal endoscopy, optical coherence tomography (OCT), and electronic staining imaging technology which includes narrow band imaging (NBI), Fujinon intelligent chromoendoscopy (FICE) and I-Scan. However, the clinical value of these techniques needs to be ascertained in the coming years. This paper reviews the progress of endoscopic diagnosis of early esophageal cancer.

Reflectance confocal microscopy for the diagnosis of eosinophilic esophagitis: a pilot study conducted on biopsy specimens

BACKGROUND

Diagnosis of eosinophilic esophagitis (EoE) currently requires endoscopic biopsy and histopathologic analysis of the biopsy specimens to count intraepithelial eosinophils. Reflectance confocal microscopy (RCM) is an endomicroscopy technology that is capable of obtaining high-resolution, optically sectioned images of esophageal mucosa without the administration of exogenous contrast.

OBJECTIVE

In this study, we investigated the capability of a high-speed form of RCM, termed spectrally encoded confocal microscopy (SECM), to count intraepithelial esophageal eosinophils and characterize other microscopic findings of EoE.

DESIGN

A total of 43 biopsy samples from 35 pediatric patients and 8 biopsy samples from 8 adult patients undergoing EGD for EoE were imaged by SECM immediately after their removal and then processed for routine histopathology. Two SECM readers, trained on adult cases, prospectively counted intraepithelial eosinophils and detected the presence of abscess, degranulation, and basal cell hyperplasia on SECM images from the pediatric patients. A pathologist blinded to the SECM data analyzed the same from corresponding slides.

SETTING

The Gastrointestinal Unit, Massachusetts General Hospital.

RESULTS

Eosinophils by SECM demonstrated a higher reflectance than the surrounding cells and other inflammatory cells. There was good correlation between SECM and histology maximum eosinophil counts/high-power field (R = 0.76, P < .0001). Intra- and interobserver correlations for SECM counts were very good (R = 0.93 and R = 0.92, respectively; P < .0001). For the commonly used eosinophil count cutoff of 15 per high-power field, the sensitivity and specificity of SECM for EoE were 100%. The sensitivity and specificity for abscess, degranulation, and basal cell hyperplasia were 100% and 82%, 91% and 60%, and 94% and 80%, respectively. Intra- and interobserver agreements for these microscopic features of EoE were very good (κ = 0.9/0.9, 0.84/1.0, 0.91/0.81, respectively).

LIMITATION

Ex vivo study.

CONCLUSIONS

This study demonstrates that RCM can be used to accurately count intraepithelial eosinophils and identify other microscopic abnormalities associated with EoE on freshly excised biopsy samples. These findings suggest that RCM may be developed into a tool for assessing eosinophilic infiltration in the esophagus in vivo.

Long-term remission of nondysplastic Barrett's esophagus after multipolar electrocoagulation ablation: report of 139 patients with 10 years of follow-up

BACKGROUND

Ablation of Barrett's esophagus (BE) has been advocated as a method to eliminate the risk of malignant transformation of BE.

OBJECTIVE

To provide longer follow-up and determine safety and efficacy of multipolar ablation for nondysplastic BE.

DESIGN

Prospective cohort study.

SETTING

Gastroenterology Unit at the Policlinica Metropolitana, a tertiary care center in Caracas, Venezuela.

PATIENTS

One hundred sixty-six patients with nondysplastic BE and histologic evidence of intestinal metaplasia.

INTERVENTIONS

Patients underwent multipolar electrocoagulation ablation therapy to areas of BE identified with magnification chromoendoscopy. The identified areas were treated with a 50-W energy source and a 7F "gold" probe. After complete ablation, patients were followed on an annual basis with magnification chromoendoscopy. At annual visits, biopsy specimens were taken in areas identified at baseline as BE. Targeted biopsy specimens were taken in areas of recurrent BE identified by using magnification chromoendoscopy.

MAIN OUTCOME MEASUREMENTS

Mortality, incidence of recurrent BE, incidence of adenocarcinoma in ablated BE, and morbidity associated with multipolar electrocoagulation.

RESULTS

One hundred sixty-six patients were recruited for the study; 139 completed at least 10 years of follow-up. Complications developed in less than 5% of patients, all of which were minor. Recurrent BE occurred in less than 5% of patients. No adenocarcinoma or high-grade dysplasia of the esophagus developed in any of the patients.

LIMITATION

Uncontrolled clinical trial.

CONCLUSIONS

Long-term follow-up of ablation of BE with multipolar electrocoagulation ablation therapy indicates that this is a safe, effective method to ablate BE over the long term.

[Endoscopic technique in endobrachyoesophagus diagnosis: Chromoendoscopy and acetic acid]

Screening for complications of neoplastic Barrett's oesophagus requires a tedious blind standardized protocol biopsies quadrant every 1 to 2cm depending on the morphology of the Barrett's epithelium (Protocol of Seattle). To achieve that biopsies targeted to areas suspicious of dysplasia, a method of high sensitivity is required. Chromoendoscopy has been developed in this direction. Acetic acid combined with high resolution endoscopy and zooming represents an aid in the preparation of the oesophageal mucosa for visualization of suspicious anomalies. It is safe, cheap and easy to use. Acetic acid has proven its value in improving the visibility of the pit pattern. Several vital dyes have been tested, including methylene blue, indigo carmine and crystal violet, with mixed results. The FICE(®) and NBI(®), immediate, reversible and attractive virtual chromoendoscopy techniques represent interesting tools for improving sensitivity in screening for Barrett's oesophagus and its complications. Confocal endomicroscopy, which is similar as a "per-endoscopic real time histological examination", seems to be equally a promising technique in detection of Barrett's oesophagus associated neoplasia. But these tools which are capable of improvement so far, have not proved their use on a large population. For this, the systematic biopsy protocol Seattle remains the "gold standard" in monitoring the Barrett's oesophagus.

Endoscopy in gastro-oesophageal reflux disease

Although gastro-oesophageal reflux disease is basically a clinical diagnosis, oesophago-gastroduodenoscopy is essential to assess the type and severity of tissue damage. The main role for endoscopy is to detect metaplastic or premalignant changes complicating gastro-oesophageal reflux, and allow for surveillance. Routine biopsies are potentially useful to increase the diagnostic precision in case of minimal mucosal abnormalities. Management algorithms should include endoscopy to be performed early in the course of disease in most patients, even in the absence of alarm symptoms. Routine use of the Los Angeles classification of oesophagitis and the Prague classification for metaplasia is necessary for a precise description and biopsy sampling. Magnification chromoendoscopy is particularly useful in the hands of experienced endoscopists, whereas novel technologies including confocal laser endomicroscopy may become an important method in specialised centres to optimise the surveillance of premalignant mucosa.

Diagnostic challenges in the pathologic evaluation of Barrett esophagus

CONTEXT

Barrett esophagus represents an unstable epithelium resulting from chronic gastroesophageal reflux disease. Patients with Barrett esophagus routinely undergo endoscopic examination to detect dysplasia and early carcinoma. Although appropriate classification of Barrett esophagus and neoplasia is usually straightforward, persistent esophageal inflammation may induce epithelial changes that mimic, or mask, dysplasia. Recent data also indicate that specific molecular changes occur in nondysplastic Barrett mucosa and herald the development of dysplasia and/or carcinoma.

OBJECTIVE

To describe problematic aspects of biopsy interpretation in tissue samples of the gastroesophageal junction and distal esophagus, including the diagnostic criteria for Barrett esophagus, the importance of the gastric cardia, and pitfalls to the diagnosis of dysplasia. Ancillary studies that have recently emerged as potential adjuncts to the evaluation of patients with Barrett esophagus will be briefly discussed.

DATA SOURCES

A comprehensive review of the relevant literature indexed in PubMed (National Library of Medicine) was performed.

CONCLUSIONS

Barrett esophagus is currently defined as the presence of intestinal metaplasia in samples obtained from an endoscopically evident abnormality in the distal esophagus. Diagnosis and grading of dysplasia in mucosal biopsies remain the most reliable method to assess risk for neoplastic progression, but its classification may be hindered by superimposed inflammatory changes and suffers from considerable interobserver variability. Therefore, immunohistochemical studies and molecular assessment for TP53, CDKN2A , and DNA content abnormalities have emerged as potential adjuncts to the detection of dysplasia.

Incidence of macroscopically occult neoplasias in Barrett's esophagus: are random biopsies dispensable in the era of advanced endoscopic imaging?

OBJECTIVES

The gold standard for endoscopic surveillance of Barrett's esophagus (BE) includes targeted biopsies (TBs) from abnormalities as well as stepwise four-quadrant biopsies (4QBs) for detection of invisible high-grade intraepithelial neoplasias (HGINs) or early carcinomas (ECs). In a large mixed BE population, we investigated the rate of HGINs/ECs that are macroscopically occult to enhanced visualization with high-resolution endoscopy plus acetic acid chromoendoscopy.

METHODS

From January 2007 to December 2009, 701 consecutive BE patients were enrolled in a prospective study at a tertiary referral center. Of these, 406 patients had a history of HGIN/EC (high-risk group) and 295 patients did not (low-risk group).

RESULTS

In 701 patients, 459 TBs and 5,485 4QBs were obtained. Altogether, 92 patients with 132 lesions containing HGINs/ECs were detected. For the diagnosis of HGINs/ECs, patient-related sensitivity and specificity rates of endoscopic imaging with TBs were 96.7 and 66.5%, with a positive and negative predictive value of 30.4 and 99.3%, respectively. In the high-risk group, 4QBs identified three additional patients (3.3%) with macroscopically occult HGINs/ECs. In the low-risk group, no HGINs/ECs were identified with either biopsy approach.

CONCLUSIONS

Advanced endoscopic imaging identifies the vast majority of BE patients with early neoplasias, and the additive effect of 4QB is minimal. Therefore, in low- and high-risk patients, limiting endoscopic surveillance to guided biopsies is justified in specialized high-volume centers with permanent quality control. However, we do not advocate abandoning 4QB outside this setting.

Acetic acid spray is an effective tool for the endoscopic detection of neoplasia in patients with Barrett's esophagus

BACKGROUND & AIMS

Diagnosis of Barrett's neoplasia requires collection of large numbers of random biopsy samples; the process is time consuming and can miss early-stage cancers. We evaluated the role of acetic acid chromoendoscopy in identifying Barrett's neoplasia.

METHODS

Data were collected from patients with Barrett's esophagus examined at a tertiary referral center, between July 2005 and November 2008 using Fujinon gastroscopes and EPX 4400 processor (n = 190). All procedures were performed by a single experienced endoscopist. Patients were examined with white light gastroscopy and visible abnormalities were identified. Acetic acid (2.5%) dye spray was used to identify potentially neoplastic areas and biopsy samples were collected from these, followed by quadrantic biopsies at 2 cm intervals of the remaining Barrett's mucosa. The chromoendoscopic diagnosis was compared with the ultimate histological diagnosis to evaluate the sensitivity of acetic acid chromoendoscopy.

RESULTS

Acetic acid chromoendoscopy had a sensitivity of 95.5% and specificity of 80% for the detection of neoplasia. There was a correlation between lesions predicted to be neoplasias by acetic acid and those diagnosed by histological analysis (r = 0.98). There was a significant improvement in the detection of neoplasia using acetic acid compared with white light endoscopy (P = .001).

CONCLUSIONS

Analysis of this large series showed that acetic acid-assisted evaluation of Barrett's esophagus detects neoplasia better than white light endoscopy, with sensitivity and specificity equal to that of histological analysis.

Endoscopic techniques for recognizing neoplasia in Barrett's esophagus: which should the clinician use?

PURPOSE OF REVIEW

The key to prevention and cure of esophageal adenocarcinoma is the detection and eradication of neoplasia in patients with Barrett's esophagus. Multiple tools and technologies are emerging for this purpose.

RECENT FINDINGS

A detailed white light examination with high-resolution endoscopy and recognition of lesions is paramount. A variety of imaging modalities are being studied for the detection of neoplasia in Barrett's esophagus. Chromoendoscopy, narrow band imaging, and autofluorescence provide a way to target suspicious areas. Confocal endomicroscopy and optical coherence tomography are means to pinpoint imaging to obtain information about the tissue microarchitecture.

SUMMARY

The key to detection of neoplasia is a careful white light examination with high-resolution endoscopy and recognition of lesion characteristics. Additional imaging modalities may enhance targeting of lesions or provide more information at a focused level. Many of these modalities have yet to be validated in prospective randomized, multicenter trials.

Comprehensive imaging of gastroesophageal biopsy samples by spectrally encoded confocal microscopy

BACKGROUND

Spectrally encoded confocal microscopy (SECM) is a high-speed reflectance confocal microscopy technique that has the potential to be used for acquiring comprehensive images of the entire distal esophagus endoscopically with subcellular resolution.

OBJECTIVE

The goal of this study was to demonstrate large-area SECM in upper GI tissues and to determine whether the images contain microstructural information that is useful for pathologic diagnosis.

DESIGN

A feasibility study.

SETTING

Gastrointestinal Unit, Massachusetts General Hospital.

PATIENTS

Fifty biopsy samples from 36 patients undergoing routine EGD were imaged by SECM, in their entirety, immediately after their removal.

RESULTS

The microstructure seen in the SECM images was similar to that seen by histopathology. Gastric cardia mucosa was clearly differentiated from squamous mucosa. Gastric fundic/body type mucosa showed more tightly packed glands than gastric cardia mucosa. Fundic gland polyps showed cystically dilated glands lined with cuboidal epithelium. The presence of intraepithelial eosinophils was detected with the cells demonstrating a characteristic bilobed nucleus. Specialized intestinal metaplasia was identified by columnar epithelium and the presence of goblet cells. Barrett's esophagus (BE) with dysplasia was differentiated from specialized intestinal metaplasia by the loss of nuclear polarity and disorganized glandular architecture.

LIMITATIONS

Ex vivo, descriptive study.

CONCLUSIONS

Large-area SECM images of gastroesophageal biopsy samples enabled the visualization of both subcellular and architectural features of various upper GI mucosal types and were similar to the corresponding histopathologic slides. These results suggest that the development of an endoscopic SECM probe is merited.

Endoscopic imaging for the detection of esophageal dysplasia and carcinoma

Numerous endoscopic imaging modalities have been developed and introduced into clinical practice to enhance diagnostic capabilities. In the past, detection of dysplasia and carcinoma of the esophagus has been dependent on biopsies taken during standard white-light endoscopy. Recent important developments in biophonotics have improved visualization of these subtle lesions sufficiently for cellular details to be seen in vivo during endoscopy. These improvements allow diagnosis to be made in gastrointestinal endoscopy units, thereby avoiding the cost, risk, and time delay involved in tissue biopsy and resection. Chromoendoscopy, narrow-band imaging, high-yield white-light endoscopy, Fujinon intelligent color enhancement, and point enhancement such as confocal laser endomicroscopy are examples of enhanced imaging technologies that are being used in daily practice. This article reviews endoscopic-based imaging techniques for the detection of esophageal dysplasia and carcinoma from the perspective of routine clinical practice.

New technologies for imaging of Barrett's esophagus

There have been many developments in endoscopy-based imaging for the detection of Barrett's syndrome, dysplasia, and neoplasia in patients with Barrett's esophagus. This article reviews the studies on and compares the efficacy of several important endoscopic imaging modalities. Some of these technologies have already achieved regulatory approval, commercial availability, and establishment of clinical utility and practical application. The future of imaging for Barrett's syndrome likely rests with the development of molecular targeting with dysplasiatargeted probes that have been conjugated to dyes or nanoparticles.

Chromoendoscopy

Chromoendoscopy involves the use of stains or dyes during endoscopy to improve the visualization and characterization of the gastrointestinal mucosa. Its main clinical application is the detection of dysplasia or early cancer of the gastrointestinal tract in individuals with pre-malignant conditions or hereditary and environmental factors that predispose them to cancer. The utility of chromoendoscopy has been mostly studied in squamous cell carcinoma of the esophagus, Barrett's esophagus, gastric cancer, colorectal polyps, and chronic ulcerative colitis. Although chromoendoscopy has been shown to be feasible and safe, several limitations have prevented its widespread use in endoscopy. Despite this, chromoendoscopy remains a useful adjunct to standard white light endoscopy in the visualization of mucosal lesions, which may potentially improve tissue diagnosis and impact patient care.

Optimal approach to obtaining mucosal biopsies for assessment of inflammatory disorders of the gastrointestinal tract

Endoscopic evaluation and mucosal biopsy analysis have assumed important roles in the clinical management of patients with symptoms related to the gastrointestinal tract. Several common inflammatory diseases, including eosinophilic esophagitis, Barrett's esophagus, Helicobacter pylori infection, celiac disease, lymphocytic colitis, collagenous colitis, and inflammatory bowel disease, may display a patchy or discontinuous distribution and, thus, multiple mucosal samples may be required to obtain diagnostic tissue in some cases. Not surprisingly, clinicians and pathologists are increasingly challenged to determine the optimum number of procedures and tissue samples necessary to detect, or exclude, the presence of inflammatory disorders of the gastrointestinal tract. Unfortunately, clinical practice varies widely with respect to tissue sample procurement in the evaluation of these disorders, particularly when the endoscopic appearance of the gastrointestinal mucosa is normal or shows only minimal changes. Guidelines concerning the appropriate number of tissue samples are well established for some diseases, such as Barrett's esophagus and chronic gastritis, but are not clear in other instances. The purpose of this review is to discuss the available literature pertaining to appropriate endoscopic sampling in the assessment of medical diseases of the gastrointestinal tract, and to develop recommendations regarding the clinical evaluation of common gastrointestinal disorders.

Barrett's esophagus: where do we stand?

Barrett's esophagus (BE) is a precursor for esophageal adenocarcinoma, which has an increased incidence rate over the last few decades. Its importance stems from the poor five-year survival of esophageal adenocarcinoma and current data that suggest a survival benefit when surveillance programs are implemented. In this review, we will cover the pathophysiology and natural history of BE and the different endoscopic findings. The prevalence of BE in different geographic areas and the incidence of high-grade dysplasia and adenocarcinoma in this patient population is reviewed. Recent recommendation for screening and surveillance of BE has been covered in this review as well as the efficacy of nonconventional imaging modalities and endoscopic ablation therapies.

Diagnostic value of magnifying endoscopy in early-stage gastrointestinal tumors and their precancerous lesions

With advance in endoscopic technology and its increasing importance in clinical diagnosis, magnifying endoscopy has attracted increasing attention and has been widely used in clinics. At present the new magnifying endoscope is able to clearly demonstrate duct openings of gastrointestinal tract mucosa and microstructural changes, thus enabling discovery and diagnosis of early lesions that are difficult for common endoscope, especially early-stage malignant tumors and precancerous lesions. Recently, magnifying endoscopy in combination with staining or with narrow-band imaging technology facilitates its wider use. This paper reviewed the diagnostic value of magnifying endoscopy in early-stage gastrointestinal tumors and precancerous lesions.

Novel imaging modalities in the detection of oesophageal neoplasia

The prognosis of oesophageal neoplasia is dependent on the stage of the disease at the time of detection. Early lesions have an excellent prognosis in contrast to more advanced stages that usually have a dismal prognosis. Therefore, the early detection of these lesions is of the utmost importance. In recent years, several new techniques have been introduced to improve the endoscopic detection of early lesions. The most important improvement, in general, has been the introduction of high-resolution/high-definition endoscopy into daily clinical practice. The value of superimposing techniques such as chromoendoscopy, narrow band imaging and computed virtual chromoendoscopy onto high-resolution/high-definition endoscopy will have to be proven in randomised cross-over trials comparing these techniques with standard techniques. Important future adjuncts to white-light endoscopy serving as 'red-flag' techniques for the detection of early neoplasia may be broad field functional imaging techniques such as video autofluorescence endoscopy. In addition, real-time histopathology during endoscopy has become possible with endocytoscopy and confocal endomicroscopy. The clinical value of these techniques needs to be ascertained in the coming years.