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.     

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.     

Endomikroskopie

Endomicroscopy becomes possible due to the integration of a miniaturized confocal microscope in the distal tip of a conventional endoscope. Endomicroscopy enables subsurface analysis of the gut mucosa and in vivo histology during ongoing endoscopy in full resolution by point scanning laser fluorescence analysis. Cellular, vascular and connective structures can be seen in detail. Graduation of cellular changes with endomicroscopy allows an immediate in-vivo diagnosis of different gastrointestinal diseases. The diagnostic spectrum of confocal endomicroscopy is currently expanding from screening and surveillance for colorectal cancer towards Barrett's esophagus, Helicobacter pylori associated gastritis and early gastric cancer. The new detailed images seen with confocal laser endomicroscopy are unequivocally the beginning of a new era where this optical development will allow a unique look on cellular structures and functions at and below the surface of the gut.     

A fluorescence confocal endomicroscope for in vivo microscopy of the upper- and the lower-GI tract

BACKGROUND: This report describes the development and the clinical evaluation of a novel confocal endomicroscope for obtaining fluorescence images of cellular morphology of the mucosae of the upper- and the lower-GI tract in vivo. The work assessed the feasibility of performing in vivo microscopy at endoscopic examination and evaluated fluorescence imaging protocols. METHODS: Images were collected in real time by using two prototype endoscope configurations, featuring slightly different miniaturized fiber-optic confocal microscopes, fitted integrally into the tips of conventional endoscopes. Confocal scanning was performed at 488 nm illumination for excitation of exogenously applied fluorophores (topical acriflavine and intravenous fluorescein). The images were compared with conventional histology of biopsy specimens and the findings of white-light endoscopy. RESULTS: Confocal endomicroscopy enabled imaging of cellular and subcellular structures (i.e., nuclei) of the GI tract. The crypts of the colonic mucosa, the villi of the terminal ileum and duodenum, the gastric pits of the stomach, and the squamous epithelium of the distal esophagus could be clearly visualized. Acriflavine strongly contrasted the cell nuclei of the surface epithelium, including the absorptive epithelial cells and the mucous secreting goblet cells. Fluorescein stained the extracellular matrix of the surface epithelium and also the subepithelial layers of the lamina propria. Images at increasing depth beneath the epithelium showed the mucosal capillary network. The findings correlated with the histology of biopsy specimens. CONCLUSIONS: The development of a fluorescence confocal endomicroscope makes it practical to examine the upper- and the lower-GI mucosa in cellular detail during otherwise routine endoscopic examination. The results represent a major technical advance in the development of this new optical imaging modality for the in vivo examination of GI tissue.     

Technology insight: Laser-scanning confocal microscopy and endocytoscopy for cellular observation of the gastrointestinal tract

Recent advances in endoscopic imaging technology have enabled the visualization of early-stage cancer and its precursors in the gastrointestinal tract. Chromoendoscopy, magnifying endoscopy, endoscopic optical coherent tomography, spectroscopy, and various combinations of these technologies, are all important for the recognition of small and unclear lesions. To observe cancer cells in vivo, two types of ultra-high magnifying endoscope--'laser-scanning confocal endoscopy series' and 'contact endoscopy series'--that have a maximum of more than 1,000x magnifying power have been developed. These endoscopes can generate high-quality images of both living cancer cells and normal cells in the gastrointestinal tract, with a quality comparable to that possible with conventional cytology. These novel imaging technologies may make in vivo histological diagnosis by virtual histology possible.     

Recent advances in targeted endoscopic imaging: Early detection of gastrointestinal neoplasms

Molecular imaging has emerged as a new discipline in gastrointestinal endoscopy.This technology encompasses modalities that can visualize disease-specific morphological or functional tissue changes based on the molecular signature of individual cells.Molecular imaging has several advantages including minimal damage to tissues,repetitive visualization,and utility for conducting quantitative analyses.Advancements in basic science coupled with endoscopy have made early detection of gastrointestinal cancer possible.Molecular imaging during gastrointestinal endoscopy requires thedevelopment of safe biomarkers and exogenous probes to detect molecular changes in cells with high specificity anda high signal-to-background ratio.Additionally,a high-resolution endoscope with an accurate wide-field viewing capability must be developed.Targeted endoscopic imaging is expected to improve early diagnosis and individual therapy of gastrointestinal cancer.     

Basic study of an agent for reinforcement of near-infrared fluorescence on tumor tissue

BACKGROUND AND AIMS: An indocyanine green derivative (ICG-sulfo-OSu) and agents for reinforcement of infrared fluorescence, which can be used as an infrared fluorescent labeling substance suitable for detection of microlesions by an IR fluorescence endoscope, have been developed. The study aims were to confirm the ability of a reinforcement agent, as well as imaging processing, to intensify fluorescence from the labeled antibody on immunohistochemical staining. SUBJECTS AND METHODS: ICG-sulfo-OSu-labeled MUC1 antibody and an IR fluorescence imaging system were employed in the present study. Paraffin sections of gastric cancer were stained with anti-MUC1 antibody by the avidin-biotinylated peroxidase complex method. Among the positive specimens, three cases were used for IR imaging analysis. Octylglucoside was used as a reinforcement agent. RESULTS: The incubation of paraffin sections with ICG-sulfo-OSu-labeled MUC1 antibody resulted in positive staining of the tumor sites by an IR fluorescence imaging system, and the intensity of fluorescence was increased depending on the concentration of octylglucoside and grade of imaging processing. CONCLUSION: A reinforcement agent, and image processing, intensify a labeled antibody excitable by infrared fluorescence in tumor sections and can generate a strong enough fluorescent signal to detect small cancers when examined with an infrared fluorescence endoscope.     

共聚焦内镜在消化道疾病诊断中的应用

共聚焦内镜是一种新的内镜成像技术,在做内镜检查的同时,即可通过点扫描激光分析获得消化道上皮高度放大的图像,不需活检和组织病理检查,就可获得组织学诊断。此文主要通过介绍该内镜技术及其所能诊断的疾病谱,来说明其在消化道疾病尤其是消化道早期肿瘤及癌前期病变的诊断和监测中的独特价值。     

Endoscopic fluorescence spectroscopy in the upper GI tract for the detection of GI cancer: initial experience

OBJECTIVE: The aim of this study was to investigate autofluorescence spectroscopy using violet-blue excitation light for the in vivo diagnosis of GI cancer during routine endoscopy. METHODS: Fluorescence spectra were obtained from normal mucosa and cancerous lesions of the esophagus and stomach. The spectroscopic system used comprised a special light source capable of delivering either white or violet-blue light to induce autofluorescence of tissue via the endoscope. Endogenous fluorescence spectra emitted by the tissue were recorded with a fiberoptic probe and analyzed with a spectrographic detector system consisting of a polychromator with a photodiode array and an optical multichannel analyzer. The data of each spectrum were sampled within the range of 450-700 nm and stored in a personal computer. RESULTS: Esophageal squamous cell cancer, adenocarcinoma of the esophagus, and adenocarcinoma of the stomach show specific differences in the emitted fluorescence spectra compared with normal mucosa. CONCLUSIONS: Light-induced fluorescence spectroscopy might be a useful tool for the endoscopic in vivo detection of dysplasia and early carcinoma in the upper GI tract. Further trials are needed to test the validity of this new optical detection system.     

Novel endoscopic imaging techniques toward in vivo observation of living cancer cells in the gastrointestinal tract

Recent advances in endoscopic imaging technology have enabled the visualization of cellular-level microstructures of early-stage cancer and its precursors. Chromoendoscopy, magnifying endoscopy, endoscopic optical coherent tomography (EOCT) spectroscopy, and various combinations of these technologies, are all important for the recognition of small and unclear lesions. In order to observe cancer cells in vivo two types of ultra-high magnifying endoscope--'laser-scanning confocal laser-scanning endoscopy series' and 'contact endoscopy series'--that have a maximum of >1,000 times magnifying power have been developed. The use of these endoscopes has allowed the generation of high quality images of both living cancer cells and normal cells in the gastrointestinal tract. In particular, clear images of cells and their nuclei, equivalent to the high quality that is possible with conventional cytology, have been produced. These novel imaging technologies may make in vivo histological diagnosis by virtual histology possible.     

Light-induced autofluorescence spectroscopy for the endoscopic detection of esophageal cancer

BACKGROUND: Any innovative optical system that facilitates the early endoscopic detection of neoplastic change in the GI mucosa has the potential to greatly improve survival and quality of life for patients prone to have GI malignancies develop. The present article describes light-induced autofluorescence spectroscopy with violet-blue excitation light for in vivo diagnosis of cancerous tissue of the esophagus during routine endoscopy. METHODS: One hundred twenty-nine endogenous fluorescence spectra were obtained from normal mucosa and malignant lesions in 9 patients with squamous cell cancer and 4 with adenocarcinoma of the esophagus. Following spectrographic measurements, biopsy specimens were obtained for definitive classification of the spectra. A special light source capable of delivering either white or violet-blue light for excitation of tissue autofluorescence by means of an endoscope was used. Endogenous fluorescence spectra emitted by tissues were detected with a fiberoptic probe and analyzed with a spectrograph. RESULTS: Squamous cell cancer and adenocarcinoma of the esophagus exhibit specific changes in the emitted fluorescence spectra as compared with normal mucosa. Based on the results obtained in earlier studies, malignant and benign spectra were differentiated with the aid of a mathematical algorithm. By using this algorithm, a sensitivity of 97% and specificity of 95% were obtained for the diagnosis of esophageal carcinoma. CONCLUSIONS: Light-induced fluorescence spectroscopy is useful for the endoscopic detection of squamous cell cancer and adenocarcinoma of the esophagus. This spectroscopic study provides a basis for the design of a simplified autofluorescence imaging system for detection of esophageal neoplasms.     

Role of digital chromoendoscopy and confocal laser endomicroscopy for gastric intestinal metaplasia and cancer surveillance

In Japan and countries such as South Korea and Tai-wan, China, the standard technique for detecting earlygastric cancer (EGC) is chromoendoscopy. This technique involves a magnified endoscope and the use ofan indigo-carmine spray to distinguish between EGCand non-EGC areas. However, this technique is notwidely adopted in many parts of the world. One important reason for limited use is that this technique needsan experienced endoscopist to interpret the imagesduring the procedure. In addition, the sensitivity for detecting gastric intestinal metaplasia (GIM), a precancerous lesion of EGC, is graded as suboptimal. Moreover,the requirement of a cumbersome spraying method isinconvenient and needs preparation time. Easier digitalchromoendoscopy techniques, such as Narrow-bandImaging and Flexible spectral Imaging Color Enhancement, have been reported to facilitate targeted GIM and EGC biopsy. They provide higher sensitivities over conventional white light endoscopy. Recently, the noveltechnology of confocal laser endomicroscopy has been introduced as a high-magnification (1000 ×) real-time evaluation for many early gastrointestinal (GI) cancersand precancerous GI lesions, including colonic polyp,Barrett’s esophagus, and GIM. The advantage of this technique is that it can be used as an in vivo confirmation of the presence of GIM and EGC during endoscopic surveillance. This review aims to explain the current information on the usefulness of digital chromoendos-copy and confocal laser endomicroscopy for evaluating GIM and EGC during endoscopic surveillance and the possible future role of these techniques for GI cancerscreening programs.     

In vivo subsurface morphological and functional cellular and subcellular imaging of the gastrointestinal tract with confocal mini-microscopy

AIM： To evaluate a newly developed hand-held confocal probe for in vivo microscopic imaging of the complete gastrointestinal tract in rodents.
METHODS： A novel rigid confocal probe （diameter 7 mm） was designed with optical features similar to the flexible endomicroscopy system for use in humans using a 488 nm single line laser for fluorophore excitation, Light emission was detected at 505 to 750 nm. The field of view was 475 μm × 475 μm. Optical slice thickness was 7 μm with a lateral resolution of 0.7 μm. Subsurface serial images at different depths （surface to 250 μm） were generated in real time at 1024 × 1024 pixels （0.8 frames/s） by placing the probe onto the tissue in gentle, stable contact. Tissue specimens were sampled for histopathological correlation.
RESULTS： The esophagus, stomach, small and large intestine and meso, liver, pancreas and gall bladder were visualised in vivo at high resolution in n = 48 mice. Real time microscopic imaging with the confocal minimicroscopy probe was easy to achieve. The different staining protocols （fluorescein, acriflavine, FITC-labelled dextran and L. esculentum lectin） each highlighted specific aspects of the tissue, and in vivo imaging correlated excellently with conventional histology. In vivo blood flow monitoring added a functional quality to morphologic imaging.
CONCLUSION： Confocal microscopy is feasible in vivo allowing the visualisation of the complete GI tract at high resolution even of subsurface tissue structures. The new confocal probe design evaluated in this study is compatible with laparoscopy and significantly expands the field of possible applications to intra-abdominal organs. It allows immediate testing of new in vivo staining and application options and therefore permits rapid transfer from animal studies to clinical use in patients.     

New optical technologies for earlier endoscopic diagnosis of premalignant gastrointestinal lesions

Gastrointestinal malignancies continue to be the second leading cause of cancer-related deaths in the developed world. The early detection and treatment of gastrointestinal preneoplasms has been demonstrated to significantly improve patient survival. Conventional screening tools include standard white light endoscopy (WLE) and frequent surveillance with biopsy. Well-defined endoscopic surveillance biopsy protocols aimed at early detection of dysplasia and malignancy have been undertaken for groups at high risk. Unfortunately, the poor sensitivity associated with WLE is a significant limitation. In this regard, major efforts continue in the development and evaluation of alternative diagnostic techniques. This review will focus on notable developments made at the forefront of research in modern gastrointestinal endoscopy based on novel optical endoscopic modalities, which rely on the interactions of light with tissues. Here we present the 'state - of - the - art' in fluorescence endoscopic imaging and spectroscopy, Raman spectroscopy, optical coherence tomography, light scattering spectroscopy, chromoendoscopy, confocal fluorescence endoscopy, and immunofluorescence endoscopy. These new developments may offer significant improvements in the diagnosis of early lesions by allowing for targeted mucosal excisional biopsies, and perhaps may even provide 'optical biopsies' of equivalent histological accuracy. This enhancement of the endoscopist's ability to detect subtle preneoplastic changes in the gastrointestional mucosa in real time and improved staging of lesions could lead to curative endoscopic ablation of these lesions and, in the long term, improve patient survival and quality of life.     

MAGNIFYING ENDOSCOPIC OBSERVATION OF THE UPPER GASTROINTESTINAL TRACT

Recent advances in technology enable us to obtain more detailed information during endoscopic procedures. Diagnosis of the pit pattern or microvascular architecture allow the earlier detection of neoplastic lesions in the gastrointestinal tract. These advances have led to the enhanced selection of appropriate treatments. Cancers that are discovered at an early stage can be treated by mucosal resection, whereas advanced cancers are treated with surgery. Recently, some groups have tried to acquire direct in vivo histological images of gastrointestinal mucosa (virtual histology or optical biopsy). Now optical coherence tomography (OCT), confocal laser endoscopy and endo‐cytoscopy systems enable this conception. However, none of these techniques has been proven, although some investigators have been able to use them to enhance cancer detection, and have reported the usefulness of these techniques. The present review assesses the strengths and weaknesses of these technologies, and describes the magnifying observations of the upper gastrointestinal tract using magnifying endoscopy equipment available on the market as well as newly developed endo‐cytoscopy systems. Published and unpublished data for this review were identified by searches of MEDLINE, Register of Cancer Trials: National Cancer Institute ( http://cancertrials.nci.nih.gov/ ) and references from relevant articles. We also contacted researchers. The authors’ own database of references was also used. The search items were as follows: magnifying endoscopy, endo‐cytoscopy system, confocal endoscopy, optical coherence tomography, contact endoscopy, esophageal cancer, Barrett’s esophagus, Barrett’s esophageal cancer, gastric cancer, colon cancer, chromoendoscopy, methylene blue etc.     

What can we see with the endoscope? Present status and future perspectives

The present status and future perspectives in new technologies of image processing and analysis, infrared ray endoscopy and autofluorescence endoscopy for gastrointestinal cancer are presented in this paper. Spectroscopic measurements using an endoscopic spectroscopic system are useful for distinguishing between benign and malignant gastric mucosal lesions, and the histological classification of early gastric cancer is possible on the basis of the spectroscopic characteristics. It is expected that adaptive hemoglobin index color enhancement would be useful for the qualitative diagnosis of early gastric cancer and for detecting specialized columnar epithelium in Barrett’s esophagus in combination with magnifying endoscopy. Our preliminary experience suggess that magnifying endoscopy with a narrow‐band imaging system could predict the histological characteristics of gastric cancerous lesions with high accuracy. Recent studies revealed that infrared ray electronic endoscopy is very useful for diagnosing the depth of invasion in early gastric cancer. In addition, it is evident that specific antibodies tagged with the indocyanine green derivative can label cancer cells and can generate a fluorescent signal strong enough to detect small cancers using an infrared fluorescence endoscope. The future development and evaluation of autofluorescence endoscopy are discussed, and we propose a modification to the system, including the excitation lights.     

Optical coherence tomography in detection of dysplasia and cancer of the gastrointestinal tract and bilio-pancreatic ductal system

Optical coherence tomography （OCT） is an optical imaging modality that performs high-resolution, crosssectional, subsurface tomographic imaging of the microstructure of tissues. The physical principle of OCT is similar to that of B-mode ultrasound imaging, except that it uses infrared light waves rather than acoustic waves. The in vivo resolution is 10-25 times better （about 10 μm） than with high-frequency ultrasound imaging, but the depth of penetration is limited to 1-3 mm, depending upon tissue structure, depth of focus of the probe used, and pressure applied to the tissue surface. In the last decade, OCT technology has evolved from an experimental laboratory tool to a new diagnostic imaging modality with a wide spectrum of clinical applications in medical practice, including the gastrointestinal （GI） tract and pancreatic-biliary ductal system. OCT imaging from the GI tract can be done in humans by using narrowdiameter, catheter-based probes that can be inserted through the accessory channel of either a conventional front-view endoscope, for investigating the epithelial structure of the GI tract, or a side-view endoscope, inside a standard transparent ERCP catheter, for investigating the pancreatico-biliary ductal system. Esophagus and the esophago-gastric junction has been the most widely investigated organ so far; more recently, also duodenum, colon and pancreatico-biliary ductal system have been extensively investigated. OCT imaging of the gastrointestinal wall structure is characterized by a multiplelayer architecture that permits an accurate evaluation of the mucosa, lamina propria, muscularis mucosae, andpart of the submucosa. The technique may be, therefore, used to identify pre-neoplastic conditions of the GI tract, such as Barrett＇s epithelium and dysplasia, and evaluate the depth of penetration of early-stage neoplastic lesions. OCT imaging of the pancreatic and biliary ductal system could improve the diagnostic accuracy for ductal epithelial changes and the differential diagnosis betw     

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.     

Endoscopic evaluation for colon cancer and dysplasia in patients with inflammatory bowel disease

Certain patients with inflammatory bowel disease (IBD) have an increased risk of developing colorectal cancer, and surveillance is recommended to detect dysplasia and early neoplasia. Endoscopic techniques that screen large mucosal surface areas for potential areas of interest that have been studied in IBD surveillance include dye-based surface chromoendoscopy with methylene blue or indigo carmine, dye-less chromoendoscopy including narrow-band imaging, i-scan, Fujinon intelligent chromoendoscopy, and autofluorescence imaging. Literature to date supports the use of surface chromoendoscopy with either methylene blue or indigo carmine to maximize dysplasia detection. Characterization of detected lesions may be further enhanced with optical biopsy technology, including confocal laser endomicroscopy and endocystoscopy, that allows in vivo histologic diagnosis that may guide both diagnosis and therapy of detected dysplastic lesions. Current and future endoscopic approaches for optimizing screening and surveillance of colon cancer and dysplasia in patients with IBD are reviewed.