Improving visualization techniques by narrow band imaging and magnification endoscopy

Endoscopy plays an important role in the early detection of gastrointestinal tract neoplasms. Using conventional white light or dye-based image enhanced endoscopy, it has been difficult to assess pre-malignant and early neoplastic lesions precisely. However, narrow band imaging (NBI) dramatically improves the detection of these lesions, particularly in combination with magnifying endoscopy. This allows the endoscopist to accomplish accurate diagnosis. Such enhanced detection of pre-malignant and early neoplastic lesions in the gastrointestinal tract should allow better targeting of biopsy, improved and more appropriate treatment, and thereby contribute to optimal quality of life and patient survival.     

Narrow-band imaging with magnifying endoscopy for the evaluation of gastrointestinal lesions

Narrow band imaging(NBI) endoscopy is an optical image enhancing technology that allows a detailed inspection of vascular and mucosal patterns, providing the ability to predict histology during real-time endoscopy. By combining NBI with magnification endoscopy(NBI-ME), the accurate assessment of lesions in the gastrointestinal tract can be achieved, as well as the early detection of neoplasia by emphasizing neovascularization. Promising results of the method in the diagnosis of premalignant and malignant lesions of gastrointestinal tract have been reported in clinical studies. The usefulness of NBI-ME as an adjunct to endoscopic therapy in clinical practice, the potential to improve diagnostic accuracy, surveillance strategies and cost-saving strategies based on this method are summarized in this review. Various classification systems of mucosal and vascular patterns used to differentiate preneoplastic and neoplastic lesions have been reviewed. We concluded that the clinical applicability of NBI-ME has increased, but standardization of endoscopic criteria and classification systems, validation in randomized multicenter trials and training programs to improve the diagnostic performance are all needed before the widespread acceptance of the method in routine practice. However, published data regarding the usefulness of NBI endoscopy are relevant in order to recommend the method as a reliable tool in diagnostic and therapy, even for less experienced endoscopists.     

内镜窄带成像技术在消化道疾病诊疗中的应用

窄带成像(NBI)内镜利用窄带滤光成像技术,突出显示消化道黏膜表面细微腺体结构及微血管形态,提高黏膜表面对比度,有利于黏膜细节的可视化,凸显白光内镜下无法显示的病灶及组织特征,极大地提高了消化道病变内镜下诊断的准确率,在诊断消化道早癌和癌前病变、判断肿瘤浸润范围和预测临床分期,判断息肉和溃疡性质等方面具有明显优势.本文...     

Chromoendoscopy

Accurate detection of premalignant lesions and early cancers in the gastrointestinal tract is essential for curative endoscopic or surgical therapy, because prognosis of the affected patients is closely related to the size and stage of the neoplastic lesion. Recently, it has emerged new endoscopic devices that allow even cellular images in vivo during an endoscopic procedure. These technologies will change and improve endoscopic diagnosis. The combination and integration of different technologies in a multifunctional endoscope will offer new optical features in GI endoscopy. Cytoendoscopy will characterize the surface architecture, confocal laser endomicroscopy will immediately clarify the nature of the lesions by in vivo histology of the mucosal layer, and optical coherence tomography will accurately grade the invasion depth. It will need some additional time before this scenario comes true. Endoscopy will become more complex due to the new visible details. Education and training will play an important future role in GI endoscopy. However, it is not possible to use these novel technologies without before learn to identify early GI cancers lesions. Meanwhile these technologies are perfectionated and we overcome the learning curve to identify early GI lesions, chromoendoscopy will continue to be a safe, easy and inexpensive method.     

Narrow band imaging and multiband imaging

NBI and MBI may enhance the diagnosis and characterization of mucosal lesions in the GI tract, particularly as adjunctive techniques to magnification endoscopy. Standardization of image characterization, further image-to-pathology correlation and validation, and the impact of these technologies on patient outcomes are necessary before endorsing the use of NBI and MBI in the routine practice of GI endoscopy.     

Endoscopic photodynamic diagnosis: oral aminolevulinic acid is a marker of GI cancer and dysplastic lesions.

BACKGROUND: Dysplasia and early cancer of the upper gastrointestinal (GI) tract often are undetected at white-light endoscopy. We describe oral administration of 5-aminolevulinic acid for the in vivo photodynamic diagnosis of premalignant and malignant lesions during endoscopy. METHODS: Four patients with known gastric adenoma (n = 1), macroscopically undetected but histologically proven esophageal squamous cell cancer (n = 1), suspected early cancer of the esophagus (n = 1), and multiple duodenal adenomas (n = 1) were sensitized with 5-aminolevulinic acid administered orally (15 mg/kg body weight). Photodynamic diagnosis was conducted after a retention time of 6 to 7 hours with a special light source capable of delivering either white or violet-blue light. Red fluorescence was detected through the gastroscope with an image-intensifying camera. RESULTS: All malignant lesions exhibited red or bluish fluorescence during photodynamic diagnosis. Fluorescence-negative mucosal areas proved to be histologically benign. CONCLUSION: Fluorescence induced with 5-aminolevulinic acid might be useful for the endoscopic detection of dysplasia and early carcinoma in the upper GI tract. Further investigations are needed to evaluate the sensitivity and specificity of photodynamic diagnosis for different tumor entities.     

Usefulness of magnifying endoscopic evaluation of the terminal ileum for a patient with graft-versus-host disease after allogeneic hematopoietic stem cell transplantation

The gastrointestinal tract is one of the common targets of acute graft-versus-host disease (GVHD), but accurate diagnosis is difficult because of the nonspecific nature of complicated diseases and the lack of diagnostic findings by conventional endoscopy. Recently, a magnifying endoscope has been developed and used for examining microstructures of the mucosa. Herein, we report the first use of a magnifying endoscope for a patient with gastrointestinal (GI) GVHD. Magnified endoscopic findings of atrophic and coalescent villi of the terminal ileum reflect histological findings of GVHD. Magnifying endoscopy of the terminal ileum may be useful for early detection and follow-up of GI GVHD.     

Neue endoskopische Methoden zur Schleimhautbeurteilung im Gastrointestinaltrakt

Technical innovations in endoscopy aim at enhanced detection and characterization of lesions of the gastrointestinal tract. High resolution endoscopy has become part of routine endoscopy and has been associated with higher detection rates in some but not all trials. Optical or software-based methods of surface contrast enhancement (e.g. NBI, i-scan, FICE) are mainly used for detailed characterization of lesions. Chromoendoscopy by topical application of intravital dyes still plays a role in detection and characterization of suspicious mucosal areas. Microscopic endoscopy methods, such as endomicroscopy and endocytoscopy not only try to predict the histology but are able to visualize pathologies at cellular and sub-cellular levels.     

Photodiagnostic techniques for the endoscopic detection of premalignant gastrointestinal lesions

Considerable attention is given to the clinical diagnosis of gastrointestinal (GI) malignancies as they remain the second leading cause of cancer‐associated deaths in developed countries. Detection and intervention at an early stage of preneoplastic development significantly improve patient survival. High‐risk assessment of asymptomatic patients is currently performed by strict endoscopic surveillance biopsy protocols aimed at early detection of dysplasia and malignancy. However, poor sensitivity associated with frequent surveillance programs incorporating conventional screening tools, such as white light endoscopy and multiple random biopsy, is a significant limitation. Recent advances in biomedical optics are illuminating new ways to detect premalignant lesions of the GI tract with endoscopy. The present review presents a summary report on the newest developments in modern GI endoscopy, which are based on novel optical endoscopic techniques: fluorescence endoscopic imaging and spectroscopy, Raman spectroscopy, light scattering spectroscopy, optical coherence tomography, chromoendoscopy, confocal fluorescence endoscopy and immunofluorescence endoscopy. Relying on the interaction of light with tissue, these ‘state‐of‐the‐art’ techniques potentially offer an improved strategy for diagnosis of early mucosal lesions by facilitating targeted excisional biopsies. Furthermore, the prospects of real‐time ‘optical biopsy’ and improved staging of lesions may significantly enhance the endoscopist's ability to detect subtle preneoplastic mucosal changes and lead to curative endoscopic ablation of these lesions. Such advancements within this specialty will be rewarded in the long term with improved patient survival and quality of life.     

Deep learning for diagnosis of precancerous lesions in upper gastrointestinal endoscopy: A review

Upper gastrointestinal (GI) cancers are the leading cause of cancer-related deaths worldwide. Early identification of precancerous lesions has been shown to minimize the incidence of GI cancers and substantiate the vital role of screening endoscopy. However, unlike GI cancers, precancerous lesions in the upper GI tract can be subtle and difficult to detect. Artificial intelligence techniques, especially deep learning algorithms with convolutional neural networks, might help endoscopists identify the precancerous lesions and reduce interobserver variability. In this review, a systematic literature search was undertaken of the Web of Science, PubMed, Cochrane Library and Embase, with an emphasis on the deep learning-based diagnosis of precancerous lesions in the upper GI tract. The status of deep learning algorithms in upper GI precancerous lesions has been systematically summarized. The challenges and recommendations targeting this field are comprehensively analyzed for future research.     

Artificial intelligence in upper GI endoscopy ‐ current status,challenges and future promise

White‐light endoscopy with biopsy is the current gold standard modality for detecting and diagnosing upper gastrointestinal (GI) pathology. However, missed lesions remain a challenge. To overcome interobserver variability and learning curve issues, artificial intelligence (AI) has recently been introduced to assist endoscopists in the detection and diagnosis of upper GI neoplasia. In contrast to AI in colonoscopy, current AI studies for upper GI endoscopy are smaller pilot studies. Researchers currently lack large volume, well‐annotated, high‐quality datasets in gastric cancer, dysplasia in Barrett's esophagus and early esophageal squamous cell cancer. This review will look at the latest studies of AI in upper GI endoscopy, discuss some of the challenges facing researchers, and predict what the future may hold in this rapidly changing field.     

Update on narrow band imaging in disorders of the upper gastrointestinal tract

With the ever‐increasing concern regarding morbidity and mortality associated with diseases of the gastrointestinal tract, the importance of an effective and efficient diagnostic tool cannot be overstated. The standard of care currently is an examination using conventional white light endoscopy. This approach may occasionally overlook areas exhibiting a premalignant change. Numerous image‐enhanced modalities have been recently introduced. Narrow band imaging (NBI) appears to be the most prominent of these and perhaps the most commonly used. Thepresent review will focus on some of the newer studies on NBI and its utility in the diagnosis of malignant, pre‐malignant and chronic inflammatory conditions of the upper gastrointestinal tract.     

WHAT'S NEW IN CHOLANGIOSCOPY? IS NARROW BAND IMAGING CHOLANGIOSCOPY THE NEXT GENERATION?

Narrow band imaging (NBI) makes it possible to emphasize the imaging of certain features such as mucosal structures and mucosal microvessels in gastrointestinal tract diseases. Recently, video peroral cholangioscopy (POCS) has been developed as diagnostic endoscopy for better observation of bile duct lesions, but there is no report on POCS using NBI. Herein is described the efficacy of POCS using NBI for the observation of both fine mucosal structures and tumor vessels, resulting in correct target biopsy in patients with biliary tract diseases.     

A REVIEW OF CURRENT CLINICAL APPLICATIONS OF UPPER GASTROINTESTINAL ZOOM ENDOSCOPY

Current clinical applications of upper gastrointestinal (GI) zoom endoscopy were reviewed. The objective of upper GI zoom endoscopy has been the diagnosis of neoplastic lesions as well as the diagnosis of minute inflammatory mucosal change. The target organ and pathology of the neoplastic lesions have been squamous cell carcinoma in the oro‐ and hypo‐pharynx and in the esophagus; intestinal metaplasia, dysplasia, and adenocarcinoma in Barrett's esophagus; and adenocarcinoma in the stomach. For analyzing the magnified endoscopic findings, there were two different basic principles (mucosal microstructural change and subepithelial microvascular changes). Overall diagnostic accuracy for diagnosing a neoplastic lesion was above 80% throughout the upper GI tract. Although the diagnostic accuracy of the zoom endoscopy technique seems to be superior to that of the ordinary endoscopy technique alone, the continuous efforts to establish standardized guidelines and procedures are mandatory in order to lead to the routine use of upper GI zoom endoscopy in clinical practice.     

Endoscopic detection of early lower gastrointestinal cancer

The prognosis for patients with malignancies of the lower gastrointestinal tract is strictly dependent on early detection of premalignant and malignant lesions. What should an ideal screening and surveillance colonoscopy be able to accomplish? The technique should allow detection of large but also discrete mucosal alterations. Ideally, endoscopic discrimination between neoplastic and non-neoplastic lesions would be possible during the ongoing procedure. At present, endoscopy can be performed with powerful new endoscopes. Comparable to the rapid development in chip technology, the optical features of the newly designed endoscopes offer resolutions, which allow new surface details to be seen. In conjunction with chromoendoscopy, the newly discovered tool video colonoscopy is much easier and more impressive today than with the previously used fibre-optic endoscopes. Recently, new endoscopic technologies such as narrow band imaging, endocytoscopy, or confocal laser endoscopy have allowed the discovery of a whole new world of image details which will surely improve the diagnostic yield in the field of early malignancies. This review summarises newly available technologies and clinical data about the diagnosis of early lower gastrointestinal cancers.     

Endoscopic detection of early upper GI cancers

The detection of early-stage neoplastic lesions in the upper GI tract is associated with improved survival and the potential for complete endoscopic resection that is minimally invasive and less morbid than surgery. Despite technological advances in standard white-light endoscopy, the ability of the endoscopist to reliably detect dysplastic and early cancerous changes in the upper GI tract remains limited. In conditions such as Barrett's oesophagus, practice guidelines recommend periodic endoscopic surveillance with multiple biopsies, a methodology that is hindered by random sampling error, inconsistent histopathological interpretation, and delay in diagnosis. Early detection may be enhanced by several promising diagnostic modalities such as chromoendoscopy, magnification endoscopy, and optical spectroscopic/imaging techniques, as these modalities offer the potential to identify in real-time lesions that are inconspicuous under conventional endoscopy. The combination of novel diagnostic techniques and local endoscopic therapies will provide the endoscopist with much needed tools that can considerably enhance the detection and management of early stage lesions in the upper GI tract.     

Magnifying chromoendoscopy for the detection of premalignant gastrointestinal lesions

The prognosis for patients with malignancies of the gastrointestinal tract is strictly dependent on the early detection of premalignant and malignant lesions. At present, endoscopy can be performed with new, powerful high-resolution or magnifying endoscopes. Comparable to the rapid development in chip technology, the optic features of the newly designed endoscopes offer resolutions that allow new mucosal surface details to be seen. In conjunction with chromoendoscopy, the newly discovered tool of video endoscopy is much easier to use and more impressive than previously used fibreoptic endoscopy. This review summarises the value of magnifying endoscopy in the upper and lower gastrointestinal tract and focuses on gastroesophageal reflux disease and early gastric and colorectal cancer.     

Magnifying endoscopy in upper gastrointestinal tract]

For the diagnosis of upper gastrointestinal (GI) lesions, magnification method is usually used in conjunction with chromoscopy, enabling the endoscopist to view subtle mucosal patterns in exquisite detail. Recently published datas have shown that magnifying endoscopy might be a valuable adjunct for the diagnosis, detection, and characterization of inflammatory and neoplastic lesions of the upper GI tract. It is also proven to be an useful surveillance protocol in identifying dysplastic epithelium or early cancer within a segment of Barrett's esophagus. Possible indications for magnifying endoscopy in upper GI tract include screening and surveillance of Barrett's esophagus, defining the extent of esophageal and gastric adenocarcinoma, detecting synchronous/metachronous gastric and esophageal cancers, diagnosing Helicobacter pylori infection, and recognizing minimal mucosal changes in gastroesophageal reflux disease. By grading the quality of evidence for the currently published trials, it is clear that the majority are case series, case reports, and/or observational studies without randomization, control, or blinding. Moreover, other evidence-based criteria such as independent, blind comparisons of magnifying endoscopy with a standard method which evaluates this technology in an appropriate spectrum of patients to whom the test may be applicable, and standardizing methodology would be crucial before magnifying endoscopy becomes a standard procedure in clinical practice. In the future, a uniform classification system for staining and magnifying patterns should be devised and observer agreement should be tested. Futher studies then could be performed based upon consistent, validated, and standardized terminologies and criteria.     

Role of endoscopy in the management of gastroenteropancreatic neuroendocrine tumours

Gastroenteropancreatic neuroendocrine tumours (GEP-NETs) represent in clinical practice a diagnostic dilemma because they are often very small, located deeply within the retroperitoneum or in an extramucosal site in the gastrointestinal (GI) tract and, lastly, because they may be multi-sited. Modern digestive endoscopy offers a myriad of techniques, useful for localization, diagnosis and treatment (therapeutic endoscopy). The available tools include upper digestive endoscopy (esophagogastroduodenoscopy, endoscopic retrograde cholangiopancreatography), lower digestive endoscopy (ileo-colonoscopy), enteroscopy (push-type, intra-operative, capsule, double or single balloon), for examining the small intestine, diagnostic and interventional echo-endoscopy (EUS), with radial, linear and miniprobe equipment. This narrative review offers scientific support to affirm that endoscopy and EUS give imaging and diagnostic possibilities that are unbeatable in the localization of GEP-NETs both of the GI tract and the pancreas. Endoscopy is useful for localization, bioptic diagnosis and curative resection of small neuroendocrine lesions of the stomach, duodenum, colon-rectum and more recently of the jejuno-ileum. EUS associated with dedicated instruments, particularly high frequency miniprobes, is a valuable procedure in locoregional staging of lesions of the GI wall and can supply information which has a clinical impact on therapeutic options and prognostic value. EUS is still today the sole technique in a certain number of cases which provides a definitive diagnosis of pancreatic insulinoma and to detect and follow subcentimetric lesions of the pancreas in patients with MEN-1 syndrome. It should be used in all those cases where results from radiographic imaging or nuclear medicine techniques show negative or dubious.     

MAGNIFYING OBSERVATION OF MICROVASCULAR ARCHITECTURE OF COLORECTAL LESIONS USING A NARROW‐BAND IMAGING SYSTEM

We reviewed the magnifying observation of the microvascular architecture of colorectal lesions and discuss the utility of the detailed observation of the microvascular architecture for differential diagnosis during narrow‐band imaging (NBI) colonoscopy. Angiogenesis is critical to the transition of premalignant lesions in a hyperproliferative state to the malignant phenotype. Therefore, diagnosis based on angiogenic or vascular morphologic changes might be ideal for early detection or diagnosis of neoplasms. In this review, we propose the term ‘meshed capillary’ for the distinction between non‐neoplastic and neoplastic lesions and the capillary classification ‘capillary pattern’ for the differential diagnosis of colorectal lesions. We believe that the combined use of NBI optical chromoendoscopy and real chromoendoscopy decreases the time and cost of screening colonoscopy. To assess the feasibility and efficacy of using the NBI system, further studies are required for colorectal lesions and other lesions of the gastrointestinal tract.