In vivo diagnosis of acute intestinal graft-versus-host disease by confocal endomicroscopy

Prospective, double-blind diagnostic multicentre study of confocal laser endomicroscopy for wheat sensitivity in patients with irritable bowel syndrome

OBJECTIVE

A considerable proportion of patients with irritable bowel syndrome (IBS) may be wheat-sensitive and respond to a gluten-free diet (GFD) although they do not have coeliac disease. However, a diagnostic test for wheat sensitivity (WS) is missing. Our study evaluated the diagnostic accuracy (sensitivity and specificity) of confocal laser endomicroscopy (CLE) for the identification of WS as primary outcome.

DESIGN

In this prospective, double-blind diagnostic study 147 non-coeliac patients fulfilling the Rome III criteria for IBS were tested by CLE for duodenal changes after wheat (index test), soy, yeast or milk exposure. Patients with IBS responding to 2 months of GFD were classified as having WS (reference test) using response criteria recommended by regulatory bodies for pharmaceutical trials of patients with IBS. After 2 months, CLE results were unblinded and patients were advised to exclude those food components that had led to a positive CLE reaction. The clinical response was assessed at follow-up after 6 and 12 months.

RESULTS

Of 130 patients who completed the study per protocol, 74 (56.9%) responded to GFD and were classified as WS after 2 months, and 38 of these 74 patients were correctly identified by CLE (sensitivity 51.4%; 97.5% CI: 38.7% to 63.9%). A total of 38 of 56 patients without WS were correctly identified by CLE (specificity 67.9%; 97.5% CI: 52.9% to 79.9%). At 6 months follow-up, CLE correctly identified 49 of 59 food-sensitive patients (sensitivity 83.1%; 97.5% CI: 69.9% to 91.3%) but specificity was only 32% (97.5% CI: 15.7% to 54.3%).

CONCLUSION

In light of the high proportion of patients with IBS responding to GFD, the diagnostic accuracy of CLE is too low to recommend widespread use of this invasive procedure.

TRAIL REGISTRATION NUMBER

This study was registered as clinical trial in the German Registry for Clinical Studies (DRKS00010123).

Early remodeling of the colonic mucosa after allogeneic hematopoietic stem cells transplantation: An open-label controlled pilot study on 19 patients

Background

Graft‐versus‐host disease (GVHD), particularly acute digestive GVHD (aDGVHD), is a severe complication of allogeneic hematopoietic stem cell transplantation (allo‐HSCT). It is necessary to identify predictive factors of GVHD to adapt prophylactic treatment.

Objective

In this context, our pilot study aimed (i) to determine whether an early remodeling of the colonic mucosa occurred after allo‐HSCT and (ii) to identify potential predictive mucosal markers of aDGVHD after allo‐HSCT.

Methods

Between day 21 and day 28 after the allo‐HSCT, 19 allo‐HSCT patients were included and had a rectosigmoidoscopy with probe‐based confocal laser endomicroscopy (pCLE) recording and biopsies. Sixteen patients were included in the control group. Morphological (pCLE), functional (intestinal permeability), and inflammatory parameters (cytokine multiplex immunoassay) were assessed.

Results

Among allo‐HSCT patients, 11 patients developed GVHD, and 6 of them developed aDGVHD. Morphological and functional changes of the colonic mucosa occurred after allo‐HSCT. Indeed, the perimeter of colonic crypts was significantly increased in allo‐HSCT patients compared to controls as well as crypt lumen fluorescein leakage (53% vs. 9%), whereas crypts sphericity, roundness, Feret diameter, and mean vessel area were significantly decreased in allo‐HSCT patients compared to the control group. In addition, interleukin‐6 (IL‐6), IL‐33, and IL‐15 levels in the supernatants of 24 h explant cultures of colonic biopsies were significantly increased in allo‐HSCT patients compared to controls. Finally, there was no difference in pCLE parameters, intestinal permeability, and inflammatory cytokines between patients who developed aDGVHD and those who did not.

Conclusion

This pilot study identified early colonic mucosa remodeling after allo‐HSCT conditioning therapy, that is morphological and functional mucosal alterations as well as mucosal inflammation. As to whether these changes are first steps in GVHD initiation and could be considered as predictive biomarkers of aDGVHD need to be determined in a larger cohort of patients.

Innovative Diagnostic Endoscopy in Inflammatory Bowel Diseases: From High-Definition to Molecular Endoscopy

High-definition endoscopy is one essential step in the initial diagnosis of inflammatory bowel disease (IBD) characterizing the extent and severity of inflammation, as well as discriminating ulcerative colitis (UC) from Crohn's disease (CD). Following general recommendations and national guidelines, individual risk stratification should define the appropriate surveillance strategy, biopsy protocol and frequency of endoscopies. Beside high-definition videoendoscopy the application of dyes applied via a spraying catheter is of additional diagnostic value with a higher detection rate of intraepithelial neoplasia (IEN). Virtual chromoendoscopy techniques (NBI, FICE, I-scan, BLI) should not be recommended as a single surveillance strategy in IBD, although newer data suggest a higher comparability to dye-based chromoendoscopy than previously assumed. First results of oral methylene blue formulation are promising for improving the acceptance rate of classical chromoendoscopy. Confocal laser endomicroscopy (CLE) is still an experimental but highly innovative endoscopic procedure with the potential to contribute to the detection of dysplastic lesions. Molecular endoscopy in IBD has taken application of CLE to a higher level and allows topical application of labeled probes, mainly antibodies, against specific target structures expressed in the tissue to predict response or failure to biological therapies. First pre-clinical and in vivo data from label-free multiphoton microscopy (MPM) are now available to characterize mucosal and submucosal inflammation on endoscopy in more detail. These new techniques now have opened the door to individualized and highly specific molecular imaging in IBD in the future and pave the path to personalized medicine approaches. The quality of evidence was stated according to the Oxford Center of evidence-based medicine (March 2009). For this review a Medline search up to January 2021 was performed using the words “inflammatory bowel disease,” “ulcerative colitis,” “crohn's disease,” “chromoendoscopy,” “high-definition endoscopy,” “confocal laser endomicroscopy,” “confocal laser microscopy,” “molecular imaging,” “multiphoton microscopy.”

Real-time imaging of head and neck squamous cell carcinomas using confocal micro-endoscopy and applicable dye: A preliminary study

OBJECTIVES

Confocal laser endomicroscopy (CLE) is a technology that enables microscopic visualization of lesions in real-time (optical biopsy) and has been successfully applied for clinical use in gastroenterology. Recently, it was also introduced for head and neck squamous cell carcinoma (HNSCC) diagnostics. We previously designed a self-made CLE, which can provide bichrome images, with topical contrast agents that are safe for use in patients. Herein, we report findings of a pilot study using our self-made CLE to image pairs of normal and cancerous tissues. This study aimed to characterize the features of HNSCC compared with normal mucosa and to establish a methodology of in vivo real-time optical biopsy of HNSCCs.

METHODS

HNSCC tissues were acquired from 10 patients who underwent surgical resection. Dissected specimens were first evaluated for their auto-fluorescence spectral profiles with 473 nm laser excitation and further optical observation. While obtaining the image, auto-fluorescence spectrum and intensity of the reflectance fluorescent signals were measured in real-time by a spectrometer. Subsequently, acriflavine was applied to the specimen to fluorescently label the nuclei and observe the difference between normal and cancerous tissues with 473 nm laser excitation. Finally, double staining with acriflavine and edible Food Red No.106 was performed to observe both nuclei and the cytoplasm of normal and cancerous tissues at 473 nm and 561 nm laser excitation.

RESULTS

Lower signals were detected from auto-fluorescence images of cancer tissues than normal tissues with 473 nm laser excitation. After acriflavine application, there was a clear difference between cancer and normal mucosa in the uniformity of nuclear size and shape. In normal mucosa, cells were arranged in an orderly manner, with each cell resembling a frog's egg. By contrast, in cancer tissues, the cell density was higher, and the cellular arrangement was less orderly. Using both acriflavine and Food Red No.106, images became more vivid, but more complicated because red dye staining of the cytoplasm emerged as fluorescence at different wavelengths.

CONCLUSIONS

Real-time in vivo imaging using the newly developed CLE and conditions may be used to distinguish cancer tissue from normal mucosa without invasive biopsy.

Acute graft-versus-host disease of the gut: considerations for the gastroenterologist

Haematopoietic stem cell transplantation (HSCT) is central to the management of many haematological disorders. A frequent complication of HSCT is acute graft-versus-host disease (GVHD), a condition in which immune cells from the donor attack healthy recipient tissues. The gastrointestinal system is among the most common sites affected by acute GVHD, and severe manifestations of acute GVHD of the gut portends a poor prognosis in patients after HSCT. Acute GVHD of the gastrointestinal tract presents both diagnostic and therapeutic challenges. Although the clinical manifestations are nonspecific and overlap with those of infection and drug toxicity, diagnosis is ultimately based on clinical criteria. As reliable serum biomarkers have not yet been validated outside of clinical trials, endoscopic and histopathological evaluation continue to be utilized in diagnosis. Once a diagnosis of gastrointestinal acute GVHD is established, therapy with systemic corticosteroids is typically initiated, and non-responders can be treated with a wide range of second-line therapies. In addition to treating the underlying disease, the management of complications including profuse diarrhoea, severe malnutrition and gastrointestinal bleeding is paramount. In this Review, we discuss strategies for the diagnosis and management of acute GVHD of the gastrointestinal tract as they pertain to the practising gastroenterologist.

Confocal endomicroscopy in diagnosis of intestinal chronic graft-versus-host disease

Graft-versus-host disease (GvHD) is a major complication of allogeneic stem cell transplantation. High-resolution in vivo histology of the intestine by confocal endomicroscopy (CEM) detects acute GvHD (aGvHD) with high sensitivity. This pilot study aims to evaluate the diagnostic value of CEM for intestinal chronic GvHD (cGvHD). The study included 20 patients with gastrointestinal symptoms and confirmed cGvHD in other organs as well as 20 patients with clinically suspected acute GvHD for control. Confocal endomicroscopy was performed as gastroscopy followed by sigmoidoscopy after intravenous injection of fluorescein (10%) and topical application of acriflavine (0.05%). Histopathology from H&E-stained biopsy samples throughout the intestinal tract complemented the survey. All histological features of intestinal cGvHD were predominantly mild to moderate. Stroma fibrosis detected by standard histology (16/20 patients) was not seen by CEM. Apoptosis assessed by histology in 12/20 patients was concordant with CEM (8/12 patients). Confocal endomicroscopy revealed esophageal manifestation of cGvHD in 3 patients. For each biopsy site, CEM correlated with intestinal histology (r = 0.64). Classical histology from intestinal biopsy samples taken under CEM monitoring confirmed the final diagnosis of cGvHD. The sensitivity of CEM with 40% in cGvHD was significantly lower compared to 70% in patients with aGvHD. Confocal endomicroscopy detected acute features of cGvHD and contributed to the diagnosis of esophageal cGvHD but failed to display stroma fibrosis in vivo. Although CEM represents a useful noninvasive tool in routine diagnostic of intestinal aGvHD, the method is not sufficient to fully establish the diagnosis of cGvHD within the intestinal tract. Confocal endomicroscopy allowed acquisition of targeted biopsies in patients suspected of having cGvHD.

Safety and Role of Gastrointestinal Endoscopy in the Management of Gastrointestinal Acute GVHD in Children After Hematopoietic Stem Cell Transplantation

Gastrointestinal (GI) endoscopy and biopsy is a common procedure to confirm the diagnosis of acute graft-versus-host disease (aGVHD) in children after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Its safety and benefits in aGVHD management is unclear. We aimed to review the safety and benefits of GI endoscopy and biopsy for GI-aGVHD management. From January 2000 to December 2009, 450 Children received allo-HSCT at SickKids. Seventy-nine (17.5%) patients underwent GI endoscopy and biopsy for suspicion of GI-aGVHD. GI-aGVHD grading was I (n=5), II (n=39), III (n=23), and IV (n=12). GI biopsy confirmed aGVHD in 49 (62%) patients and results were negative in 30 (38%). Thirty-two (40%) patients started treatment based on clinical criteria before procedure. Twenty-four out of 79 patients had a change in therapy because of biopsy results. Treatment change was significantly more common in patients who had a positive biopsy results compared with those with negative results (24/49 vs. 4/30, P=0.02). Comparing patients who started therapy before the biopsy results (n=32) and the remaining patients (n=47) who were not started on therapy, the biopsy results had more impact in altering/starting therapy in these patients (24/47 vs. 0/32, P<0.00001). For the 32 patients who started therapy before the procedure, the biopsy confirmed aGVHD diagnosis in 20 of them (63%). Only 1 patient (1.25%) had duodenal hematoma and needed prolong GI rest and ultimately recovered. GI endoscopy and biopsy was safe and useful in guiding therapy for GI-aGVHD.

Confocal fluorescence microscopy to evaluate changes in adipocytes in the tumor microenvironment associated with invasive ductal carcinoma and ductal carcinoma in situ

Adipose tissue is a dynamic organ that provides endocrine, inflammatory and angiogenic factors, which can assist breast carcinoma cells with invasion and metastasis. Previous studies have shown that adipocytes adjacent to carcinoma, known as cancer-associated adipocytes, undergo extensive changes that correspond to an "activated phenotype," such as reduced size relative to adipocytes in non-neoplastic breast tissue. Optical imaging provides a tool that can be used to characterize adipocyte morphology and other features of the tumor microenvironment. In this study, we used confocal fluorescence microscopy to acquire images of freshly excised breast tissue stained topically with proflavine. We developed a computerized algorithm to identify and quantitatively measure phenotypic properties of adipocytes located adjacent to and far from normal collagen, ductal carcinoma in situ and invasive ductal carcinoma. Adipocytes were measured in confocal fluorescence images of fresh breast tissue collected from 22 patients. Results show that adipocytes adjacent to neoplastic tissue margins have significantly smaller area compared to adipocytes far from the margins of neoplastic lesions and compared to adipocytes adjacent to non-neoplastic collagenous stroma. These findings suggest that confocal microscopic images can be utilized to evaluate phenotypic properties of adipocytes in breast stroma which may be useful in defining alterations in microenvironment that may aid in the development and progression of neoplastic lesions.

Confocal Laser Endomicroscopy in Gastrointestinal and Pancreatobiliary Diseases: A Systematic Review and Meta-Analysis

Confocal laser endomicroscopy (CLE) is an endoscopic-assisted technique developed to obtain histopathological diagnoses of gastrointestinal and pancreatobiliary diseases in real time. The objective of this systematic review is to analyze the current literature on CLE and to evaluate the applicability and diagnostic yield of CLE in patients with gastrointestinal and pancreatobiliary diseases. A literature search was performed on MEDLINE, EMBASE, Scopus, and Cochrane Oral Health Group Specialized Register, using pertinent keywords without time limitations. Both prospective and retrospective clinical studies that evaluated the sensitivity, specificity, or accuracy of CLE were eligible for inclusion. Of 662 articles identified, 102 studies were included in the systematic review. The studies were conducted between 2004 and 2015 in 16 different countries. CLE demonstrated high sensitivity and specificity in the detection of dysplasia in Barrett's esophagus, gastric neoplasms and polyps, colorectal cancers in inflammatory bowel disease, malignant pancreatobiliary strictures, and pancreatic cysts. Although CLE has several promising applications, its use has been limited by its low availability, high cost, and need of specific operator training. Further clinical trials with a particular focus on cost-effectiveness and medicoeconomic analyses, as well as standardized institutional training, are advocated to implement CLE in routine clinical practice.

Characterization of lesions in the stomach: will confocal laser endomicroscopy replace the pathologist?

Confocal laser endomicroscopy (CLE) permits microscopic visualization of the mucosa during endoscopy at an approximately 1000fold magnification, permitting endoscopists to obtain microscopic analysis during gastroscopy. This can result in optimized diagnosis of diffuse alterations such as gastric atrophy and intestinal metaplasia and may limit the sampling error of untargeted biopsies. It also allows risk stratification prior to endoscopic therapy of neoplastic lesions of the stomach. In these areas, CLE represents a valuable adjunct for targeted histopathology. In addition, CLE allows on-site in vivo imaging, and by this insight into physiologic and pathophysiologic as well as molecular events of the stomach without major artifacts.

Early detection of acute graft-versus-host disease by wireless capsule endoscopy and probe-based confocal laser endomicroscopy: results of a pilot study

OBJECTIVE

Acute gastrointestinal graft-versus-host disease (GI-GVHD) is usually diagnosed using endoscopic examinations and biopsies for conventional histology. The aim of this pilot study was to determine whether mini-invasive techniques such as probe-based confocal laser endomicroscopy (pCLE) combined with wireless capsule endoscopy (WCE) could detect early lesions of GI-GVHD prior to symptoms.

DESIGN

Fifteen patients undergoing allogeneic haematopoietic stem cell transplantation (allo-HSCT) were prospectively examined with a small bowel WCE, duodenal and colorectal pCLE, and standard biopsies. Per study protocol, all these examinations were scheduled between day 21 and day 28 after allo-HSCT, independently of the presence or absence of digestive symptoms.

RESULTS

During follow up, eight patients developed acute GI-GVHD. Sensitivity of WCE, pCLE, and histology were 50, 87.5, and 50%, respectively. Specificity of WCE, pCLE, and histology were 80, 71.5, and 80%, respectively. We showed a positive correlation between the Glücksberg scoring system and WCE (rho = 0.543, p = 0.036) and pCLE (rho = 0.727, p = 0.002) but not with standard histology (rho = 0.481, p = 0.069).

CONCLUSIONS

The results from this pilot study suggest that novel methods such as pCLE and WCE could be part of a mini-invasive algorithm for early detection of GI-GVHD.

New insight for the diagnosis of gastrointestinal acute graft-versus-host disease

Allogeneic stem cell transplantation (allo-SCT) is a curative therapy for different life-threatening malignant and nonmalignant hematologic disorders. Graft-versus-host disease (GVHD) remains a major source of morbidity and mortality following allo-SCT, which limits the use of this treatment in a broader spectrum of patients. Early diagnostic of GVHD is essential to initiate treatment as soon as possible. Unfortunately, the diagnosis of GVHD may be difficult to establish, because of the nonspecific nature of the associated symptoms and of the numerous differential diagnosis. This is particularly true regarding gastrointestinal (GI) acute GVHD. In the recent years many progress has been made in medical imaging test and endoscopic techniques. The interest of these different techniques in the diagnosis of GI acute GVHD has been evaluated in several studies. With this background we review the contributions, limitations, and future prospect of these techniques in the diagnosis of GI acute GVHD.

Microscopic imaging in endoscopy: endomicroscopy and endocytoscopy

Performing real-time microscopy has been a vision of endoscopists since the very early phases of gastrointestinal endoscopy. Confocal endomicroscopy, an adaption of confocal laser scanning microscopy, and endocytoscopy, an adaption of white-light microscopy, have been introduced into the endoscopic armamentarium in the past decade. Both techniques yield on-site histological information. Multiple trials have demonstrated the ability of gastroenterologists to obtain and interpret microscopic images from the upper and lower gastrointestinal tract, and also the hepatobiliary-pancreatic system, during endoscopy. Such microscopic information has been successfully used in expert hands to minimize sampling error by 'smart', microscopically targeted biopsies and to guide endoscopic interventions. However, endomicroscopy is also unique in its ability to dynamically visualize cellular processes in their native environment free of artefacts. This ability enables fundamental insights into mechanisms of human diseases in clinical and translational science.

Confocal Laser Endomicroscopy: Applications in Clinical and Translational Science—A Comprehensive Review

Confocal laser endomicroscopy (CLE) is a novel tool in the endoscopist’s armamentarium. It allows on-site histological information. The ability of gastroenterologists to interpret such microscopic information has been demonstrated in multiple studies from the upper and lower gastrointestinal tract. Recently, the field of application has expanded to provide hepatobiliary and intra-abdominal CLE imaging. CLE allows “smart,” targeted biopsies and is able to guide endoscopic interventions. But CLE is also translational in its approach and permits functional imaging that significantly impacts on our understanding of gastrointestinal diseases. Molecular imaging with CLE allows detection and characterization of lesions and may even be used for prediction of response to targeted therapy. This paper provides a comprehensive review over current applications of CLE in clinical applications and translational science.

Ultra high magnification endoscopy: Is seeing really believing?

Endoscopy is an indispensible diagnostic and therapeutic instrument for gastrointestinal diseases. Endocytoscopy and confocal endomicroscopy are two types of ultra high magnification endoscopy techniques. Standard endoscopy allows for 50 × magnification, whereas endocytoscopy can magnify up to 1400 × and confocal endomicroscopy can magnify up to 1000 ×. These methods open the realm of real time microscopic evaluation of the GI tract, including cellular and subcellular structures. Confocal endomicroscopy has the additional advantage of being able to visualize subsurface structures. The use of high magnification endoscopy in conjunction with standard endoscopy allows for a real-time microscopic assessment of areas with macroscopic abnormalities, providing “virtual biopsies” with valuable information about cellular and subcellular changes. This can minimize the number of biopsies taken at the time of endoscopy. The use of this technology may assist in detecting pre-malignant or malignant changes at an earlier state, allowing for earlier intervention and treatment. High magnification endoscopy has shown promising results in clinical trials for Barrett’s esophagus, esophageal adenocarcinoma, esophageal squamous cell cancer, gastric cancer, celiac disease, colorectal cancer, and inflammatory bowel disease. As the use of high magnification endoscopy techniques increases, the clinical applications will increase as well. Of the two systems, only confocal endomicroscopy is currently commercially available. Like all new technologies there will be an initial learning curve before operators become proficient in obtaining high quality images and discerning abnormal from normal pathology. Validated criteria for the diagnosis of the various gastrointestinal diseases will need to be developed for each method. In this review, the basic principles of both modalities are discussed, along with their clinical applicability and limitations.

Technicalities of colonoscopy: endoscopic microscopy - where are we heading?

Confocal laser endomicroscopy (CLE) is a new endoscopic imaging tool enabling in vivo histology during ongoing endoscopy. Basically, three different patterns can be seen in the colon: normal, neoplastic and inflammatory mucosa. Several pilot studies have shown an excellent correlation with classical histology. However, what could be the future indications of CLE? (1) Differentiating neoplastic from inflammatory changes constitutes a promising diagnostic tool in screening for dysplasia in ulcerative colitis. This can help to further increase the efficacy of chromoendoscopy in dysplasia detection and reduce the number of biopsies. The possibility to differentiate sporadic adenoma from dysplasia-associated lesion or mass could have an immediate impact on patient management. (2) The diagnosis of collagenous colitis depends on multiple random biopsies. Case series have shown that CLE can guide the endoscopist to take more representative biopsies to make the diagnosis. Large prospective trials are needed to confirm this finding. (3) An interesting clinical application is graft-versus-host disease (GVHD). A pilot study showed that it was possible to predict the presence of GVHD in 14/19 patients with GVHD out of 35 patients who were referred for diarrhea after stem cell transplantation. (4) CLE for standard polyp surveillance is probably redundant since it will not change patient management at this stage. Moreover, it can currently not differentiate between classical hyperplastic and sessile serrated adenomas. (5) Future additional technological improvements of the system with faster Z-scanning, deeper light penetration and 3D reconstruction will help to improve the quality of CLE. Reports on in vivo molecular imaging and assessment of physiological changes provide a promising glance at the future possibilities of CLE imaging.

In vivo real-time imaging of the liver with confocal endomicroscopy permits visualization of the temporospatial patterns of hepatocyte apoptosis

Apoptosis is a dynamic process of programmed cell death and is involved in multiple diseases. However, its mechanisms and sequence of events are still incompletely understood, partly because of the inability to visualize single cells continuously in vivo. The aim of the present study was to monitor hepatocyte apoptosis with confocal endomicroscopy in living rodents. In 73 anaesthetized mice, apoptotic liver injury was induced by injection of the CD95-agonistic antibody Jo2. Individual hepatocytes were followed for up to 240 min with a handheld confocal probe (FIVE1; Optiscan) providing 0.7 μm resolution (1,000-fold magnification). Different fluorescence staining protocols were used for cellular staining, vascular and cellular barrier function imaging, and caspase activation visualization. The time course of apoptosis could be visualized in vivo while liver perfusion and tissue integrity were maintained. In contrast to most ex vivo studies, initial cell swelling was observed that coincided with early defects in barrier function of sinusoids and hepatocytes. Cytoplasmic vesicle formation, nuclear condensation, cellular disintegration, and macrophage infiltration were captured sequentially. Labeling of caspases allowed molecular imaging. Our study allowed for the first time to continuously follow distinct morphological, functional, and molecular features of apoptosis in a solid organ in vivo and at high resolution. Intravital confocal microscopy may be a valuable tool to study the effects of therapeutic intervention on apoptosis in animal models and humans.

Confocal laser endomicroscopy in gastrointestinal diseases

Confocal laser endomicroscopy (CLE) is a novel endoscopic technique permitting in vivo microscopy (optical biopsies) of the gastrointestinal mucosa. CLE has been studied in a multitude of diseases of the upper and lower gastrointestinal tract, including Barrett's esophagus, gastric inflammation and cancer, celiac disease, colorectal adenoma and carcinoma, and inflammatory bowel diseases. CLE has recently evolved and been studied for bile duct and liver imaging. CLE has shown overall high accuracy and enabled smart, targeted biopsies rather than untargeted sampling. Furthermore, the availability of real time microscopic information during endoscopy has immediate impact on therapeutic decisions and guides endoscopic interventions. CLE is also a unique tool for observation of (patho-)physiologic events in their natural environment (functional imaging) and has been linked to molecular imaging of gastrointestinal neoplasia in vivo, thereby broadening our understanding of mucosal pathology in clinical and basic science.

Enhanced mucosal imaging

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Advances of endomicroscopy for gastrointestinal physiology and diseases

Confocal endomicroscopy is a novel technique that permits in vivo microscopy of the human gastrointestinal mucosa during ongoing endoscopy, thereby providing optical virtual biopsies. Endomicroscopy has been demonstrated to reveal histological information in a multitude of diseases in the upper and lower gastrointestinal tract in vivo. Most studies have focused on inflammation and neoplasia, such as Barrett's esophagus, gastric cancer, celiac disease, Crohn's disease and ulcerative colitis, or colorectal neoplasias. Endomicroscopy allows obtainment of "smart," targeted biopsies from regions with microscopic alterations rather than having to rely on random untargeted tissue sampling. This reduces the number of biopsies while increasing the diagnostic yield. In addition, immediate histological information is available, enabling immediate therapy. Apart from morphological visualization, endomicroscopy offers a unique possibility to study pathophysiological events in their natural environment (functional imaging). Molecular imaging with endomicroscopy applied in clinical and basic science will permit advances in understanding of the cellular basis of gastrointestinal physiology and pathophysiology.