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During the past decade, molecular imaging has emerged as a new and innovative field combining clinical endoscopy with methods prior used in basic science. Through the labeling of cellular targets with certain molecular probes and their subsequent detection with dedicated endoscopic devices, molecular imaging enables the visualization of single molecules or receptors during ongoing endoscopy. Early studies in the field have provided proof-of-principle that molecular imaging can improve visualization, or even unmask, previously unrecognized early dysplasia or cancer. Building on this, further studies then used molecular imaging for grading and detecting inflammation and inflammation associated cancer. Most recently, molecular imaging has been used to phenotype the expression of single receptors and targets of biological therapy and thereby enables molecular tissue profile in vivo. With this live molecular fingerprinting, molecular imaging can be used to guide expression-tailored individualized therapy, and due to the diversification of biological therapy in both cancer and intestinal inflammation, it can be expected that molecular imaging will gain further traction in the foreseeable future. Within this review, we first summarize the technical components commonly used for molecular imaging and then review preclinical and clinical studies and possible and evolving clinical applications on molecular imaging within the entire the GI tract.

Background: Endoscopic resection of dysplastic lesions in early stages of cancer reduces mortality rates and is recommended by many national guidelines throughout the world. Snare polypectomy and endoscopic mucosal resection (EMR) are established techniques of polyp removal. The advantages of these methods are their relatively short procedure times and acceptable complication rates. The latter include delayed bleeding in 0.9% and a perforation risk of 0.4–1.3%, depending on the size and location of the resected lesion. EMR is a recent modification of endoscopic resection. A limited number of studies suggest that larger lesions can be removed en bloc with low complication rates and short procedure times. Novel techniques such as endoscopic submucosal dissection (ESD) are used to enhance en bloc resection rates for larger, flat, or sessile lesions. Endoscopic full-thickness resection (EFTR) is employed for non-lifting lesions or those not easily amenable to resection. Procedures such as ESD or EFTR are emerging standards for lesions inaccessible to EMR techniques. Summary: Endoscopic treatment is now regarded as first-line therapy for benign lesions. Key Message: Endoscopic resection of dysplastic lesions or early stages of cancer is recommended. A plethora of different techniques can be used dependent on the lesions.

Inflammatory bowel diseases (IBD) are complex diseases. Epidemiological studies suggest rising incidences in industrialized countries. The article is based on a literature search in PubMed and is oriented on the current guidelines published by the European Crohn's and Colitis Organisation. IBD are characterized by chronic diarrhoea, abdominal pain and peranal haemorrhage. Extraintestinal manifestations commonly affect joints, skin, eyes and bile tracts. Early diagnosis and therapeutic intervention determine individual patient outcome. Medical treatment currently includes aminosalicylates, corticosteroids, thiopurines, calcineurin inhibitors and biologicals. IBDs require anti-inflammatory and if necessary immunosuppressive therapy. Due to extraintestinal complications and the possible need for surgical intervention, an interdisciplinary approach is important.

Wichtigstes Mittel fur die Diagnose eines Morbus Crohn und die Beurteilung der entzundlichen Aktivitat ist die Endoskopie mit histologischer Begutachtung. Da diese Methode aufwandig und oft problematisch ist, wurden in den letzten Jahren zunehmend nicht-invasive Methoden (fort)entwickelt. Hierbei spielen Biomarker eine bedeutende Rolle.

Background Vedolizumab has emerged as an important pillar of treatment in inflammatory bowel disease (IBD). However, for unknown reasons, not all patients respond to therapy. Earlier clinical studies suggested decreased response rates in the highest compared with medium dosage groups. Interestingly, vedolizumab has been shown to inhibit the homing of both regulatory (Treg) and effector T (Teff) cells and previous data from our group suggested different effect sizes in both populations. Thus, we hypothesised that the non-linear exposure–efficacy correlation might be explained by dose-dependent differential effects of vedolizumab on Treg and Teff homing. Therefore, we studied functional effects of different vedolizumab exposure levels on Treg and Teff cell trafficking. Methods The α4β7 expression on different human T-cell subsets as well as the binding characteristics of vedolizumab to these cells at different exposure levels was analysed via flow cytometry. Functional effects of different vedolizumab concentrations on the adhesion of Tregs and Teffs to mucosal addressin cell adhesion molecule 1 (MAdCAM-1) were analysed using dynamic in vitro adhesion assays, transmigration assays and in vivo homing assays in a humanised mouse model. The in vivo binding of vedolizumab to Tregs and Teffs in patients receiving therapy was quantified and correlated with the corresponding serum levels. Results We found a preferential binding of vedolizumab to Tregs at an exposure with 0.4 µg/ml vedolizumab that shifted to a preferential binding to Teffs at an exposure with 10 µg/ml. Further increase of vedolizumab to 50 µg/ml led to equal binding to Tregs and Teffs (Figure 1). Consistently, at 10 µg/ml, dynamic adhesion of Tregs to MAdCAM-1 was increased compared with Teffs, but no difference was noted at 50 µg/ml. Additionally, a higher number of Treg compared with Teff cells were able to transmigrate in a MAdCAM-1-dependent manner at a concentration of 10 µg/ml vedolizumab. Preliminary data from homing experiments in a humanised mouse model and from IBD patients treated with vedolizumab support the notion that differential binding preferences depending on the exposure level can also be observed in vivo. Conclusion Our findings support a dose-dependent differential binding of vedolizumab to different T-cell subpopulations and suggest that an optimal ‘window’ of exposure exists, in which effects on Teffs predominate over Tregs. While offering a potential explanation for earlier findings in dose-ranging studies, our data might lay the basis for the establishment of individualised dose optimisation in IBD patients.

Background Interferons (IFNs) are immune-modulatory cytokines expressed by epithelial and mucosal cells in response to viral and bacterial infection. Just recently, we discovered a correlation between IFN-λ expression and disease activity, including small intestinal inflammation and Paneth cell dysfunction, in human Crohn’s disease patients. On a molecular level, we uncovered that IFN-λ mediates epithelial cell death, in particular, Paneth cell death by a programmed necrosis, dependent on STAT1 activation and controlled by caspase-8. These results suggested that IFN-λ can be considered as a pathogenic cytokine in Crohn′s ileitis and should be considered as a new and promising target for future therapeutic intervention for this particular subtype of IBD. Our central question is now by which pathways interferon-regulated programmed necrosis of epithelial cells contributes to intestinal inflammation and how these mechanisms could be targeted for future therapeutic intervention. Methods We use a mouse model for Crohn’s Disease like inflammation and Paneth cell death that has a specific deletion of Caspase-8 in intestinal epithelial cells (Casp8∆IEC). We stimulate small intestinal organoids derived from Casp8∆IEC mice with IFNs in vitro and we overexpress IFN-λ in these mice in vivo by hydrodynamic tail vein injection of an IFN-λ expression vector. Furthermore, we use JAK-inhibitors to impede pharmacologically cell death pathways in the pathogenesis of intestinal inflammation in vitro and in vivo. Results We uncovered that gene expression of the cell death mediators Mlkl and Caspase-8 is dependent on IFN-λ-mediated JAK-STAT1 signalling. The non-specific pan JAK-inhibitor Tofacitinib is able to attenuate gene expression of Mlkl and Caspase-8 in vitro as well as in vivo. It prevents non-apoptotic as well as apoptotic cell death of small intestinal organoids stimulated with IFN-λ and is sufficient to prevent small intestinal tissue destruction in Casp8∆IEC mice challenged with IFN-λ. Additionally, we use the selective JAK1-inhibitor Filgotinib to limit the targeted JAK-STAT signalling pathways to only JAK1-STAT1 signalling and thus reduce side effects of the inhibitor on other signalling pathways. This had a similar effect as Tofacitinib suggesting that IFN controls MLKL-mediated cell death via JAK1. Conclusion In summary, our results indicate that targeting IFN-λ-mediated JAK-STAT1 signalling by the small-molecules Tofacitinib and Filgotinib impedes induction of Mlkl and Caspase-8-mediated cell death pathways. Therefore, JAK1 inhibitors such as Filgotinib might represent a promising novel therapy that may be sufficient to achieve efficacy particularly in Crohn′s ileitis patients who display elevated IFN-l serum levels.

Background SB2 is a biosimilar infliximab approved for the treatment of inflammatory bowel disease (IBD) patients. These are the first prospective data investigating long-term efficacy, safety, and pharmacokinetics after switching from infliximab originator to biosimilar SB2 in IBD patients. Methods This is a prospective, observational cohort study of patients that underwent a switch from infliximab originator to biosimilar SB2 in 2017 as part of routine care at the outpatient Clinic for IBD at the University Hospital of Erlangen, Germany. Long-term safety and clinical effectiveness were recorded over a follow-up period of 18-months. Clinical disease activity was assessed by the Harvey–Bradshaw Index (HBI) in Crohn’s disease (CD) and the partial Mayo Score (pMS) in ulcerative colitis (UC) patients. C-reactive protein (CRP) was analyzed at every patient visit, and IFX trough-level (TL) and anti-IFX antibodies (ADA) were measured prior to every SB2 administration, using the Promonitor® tests. The occurrence of adverse events was registered at every patient visit. Results A total of 148 IBD patients (96 CD, 52 UC) was enrolled. The median duration of previous infliximab treatment before the switch was 29 months (range 1.0–110.0). Median disease activity in CD was an HBI of 3 (0–16) at switch (baseline), 2 (0–13) at month 6, 3 (0–15) at month 12 and 2.5 (0–11) at month 18. Median disease activity in UC was a pMS of 0 (0–6) at baseline, 1 (0–4) at month 6, 1 (0–4) at month 12 and 1 (0–5) at month 18. The median TL for all IBD patients was 6.3 mg/ml (0.1–33.7) at baseline, 5.0 mg/ml (0.1–34.3) at month 6, 6.3 mg/ml (0.1–35.8) at month 12 and 5.1 mg/ml (0.1–35.4) at month 18. CRP for all IBD patients was 2.2 mg/l (0.1–45.6) at baseline, 2.2 mg/l (0.1–90.4) at month 6, 2.3 mg/l (0.1–169.5) at month 12 and 2.7 mg/l (0.1–19.8) at month 18. In the 18-month follow-up period, 12/103 (11.7%) of patients who were ADA-negative at baseline developed ADA post-switch. Altogether, 40 (27%) IBD patients discontinued SB2 treatment during the 18-month follow-up period (4 anaphylaxis, 20 loss of response, 7 non-serious and 9 serious adverse events), 2 paused during pregnancy, 1 discontinued in clinical remission, 10 were lost to follow-up (7 change of physician, 3 unknown). Serious adverse events comprised 3 malignancies (breast and prostate carcinoma, neuroendocrine malignancy), 1 liver abscess and 5 intestinal surgical procedures (1 perforation, 1 ileus, and 3 stenoses). Conclusion Switching from IFX originator to biosimilar SB2 was not associated with an increase in disease activity. No clinically meaningful changes in IFX trough levels or immunogenicity were identified. Altogether, SB2 was well tolerated in a real-life setting.

In the work-up of focal pancreatic lesions autoimmune pancreatitis (AIP) is a rare differential diagnosis to pancreatic cancer (PC) with similar clinical constellations. The aim of our study was to compare differences between proven AIP and PC using transabdominal dynamic contrast enhanced ultrasound (DCE-US). Therefore we recorded 3-minute-clips of CEUS examinations and analyzed perfusion parameters with VueBox®-quantification software. To obtain DCE-US Parameters, Regions-of-Interest were selected within the lesions and the surrounding pancreas parenchyma, serving as reference tissue. We compared 3 patients with AIP (mean age: 58 years; lesion mean size: 40 mm) to 17 patients with PC (mean age: 68 years; lesion mean size: 35.9 mm). Significant differences between PC and parenchyma could be found in the following parameters: Peak-Enhancement (PE), Wash-in-and-Wash-out-AUC, Wash-in Perfusion-Index. PE of AIP was comparable to normal parenchyma. The relation of PE between parenchyma and lesion (ΔPE) AIP and PC was significantly different [AIP: 0.21 (±0.06); PC: 0.81 (±0.1); p

In der Erstdiagnostik der chronisch entzundlichen Darmerkrankungen gehort eine komplette Ileokoloskopie zu den wichtigsten diagnostischen Masnahmen, und auch im spateren Verlauf der Behandlung bleibt das Endoskop ein unersetzliches Werkzeug fur den Arzt. Ein Uberblick uber die wichtigsten und haufigsten Verfahren — und ihre Risiken.

The Acknowledgement Statement was incorrect in the original publication of this article [1] and the previous correction note [2]. The correct statement is as follows

Hintergrund: Eine Akkumulation von eosinophilen Granulozyten (EG) am Gastrointestinaltrakt (GIT) kann aus verschiedenen pathogenetischen Ursachen erfolgen (Allergie, Autoimmunitat, idiopathische eosinophile Gastroenteritis, Neoplasie, Parasitose, Vaskulitis etc). Die eosinophile Infiltration kann von der Speiserohre bis zum Rektum jeden Organabschnitt isoliert oder kontinuierlich betreffen. Die eosinophile Osophagitis (Eo E) wurde in den letzten beiden Jahrzehnten wesentlich haufiger diagnostiziert und stellt eine wichtige Differenzialdiagnose von Patienten mit Dysphagie, refluxartigen Beschwerden, Motilitatsstorungen oder bei Thorax- und Abdominalschmerzen dar. Methodik: Die zur Diagnostik der Eo E benutzten Kriterien wurden aus dem Interdisziplinaren Datenregister fur chronisch entzundliche und allergische Magen-Darm-Erkrankungen der Universitat Erlangen analysiert extrahiert und mit einer selektiven Literaturrecherche zum Zeitpunkt Dezember 2012 zusammengefasst. Ergebnisse und Schlussfolgerung: Die Diagnostik der Eo E verlangt bei der Anamnese (z. B. veranderte Nahrungsaufnahme, Schluckstorungen, Thoraxdruck, allergische Vorerkrankungen) und bei der Endoskopie hochste Aufmerksamkeit, denn nicht selten finden sich nur diskrete Hinweise oder Auffalligkeiten der Osophagusmukosa. Typische Zeichen sind Bolusobstruktion bei jungen Mannern, erhohte Verletzbarkeit der Schleimhaut oder Ringbildungen. Die Eo E zeigt in nur ca. einem Drittel aller Falle typische endoskopische Zeichen (weise Papeln, Ring- oder Langsfurchen, Strikturen), ein Drittel zeigt verdachtige Befunde (Odem, Kontaktvulnerabilitat, blasse Mukosa) und ein Drittel ist endoskopisch unauffallig. Die endoskopische Diagnostik muss obligat histologisch durch Stufenbiopsien aus dem Osophagus erganzt werden. Die Diagnose ist gesichert, wenn mehr als 15 – 20 Eosinophile pro hochauflosendes Blickfeld (HPF) im proximalen und distalen Osophagus nachgewiesen werden konnen. Als fakultative Diagnostikmodalitaten gelten pH-Metrie, Manometrie, radiologischer KM-Schluck, Endosonografie und Thorax-Computertomografie, die nur bei speziellen Fragestellungen hinzugezogen werden mussen. Bei thorakalem Druckgefuhl sind kardiale Grunderkrankungen zu uberprufen. Weitere wichtige Differenzialdiagnosen sind die Refluxerkrankung, Mitbeteiligung des Osophagus bei Systemerkrankungen (Autoimmunopathie) oder eosinophile Gastro-Enterocolitiden und hypereosinophiles Syndrom.

Lymphoid hyperplasia of the intestine has been associated with multiple diseases and symptoms. This study was undertaken to analyze the number and topographical distribution of the lymphoid follicles. A total of 302 adult consecutive patients were enrolled when they underwent elective colonoscopy. Standardized pictures from terminal ileum and colon were taken using video colonoscopes. In each picture, the number, size, and mucosal elevation of lymphoid follicles were analyzed in relation to histological and immunological findings and medical history. Lymphoid hyperplasia was found to be most extensive in the terminal ileum and cecum. Patients with untreated gastrointestinally mediated allergy (GMA) showed the highest number of lymphoid follicles per visible field in the terminal ileum ( P < 0.001) and cecum ( P = 0.003) vs. the control group. Patients with infectious colitis also showed a high number of lymphoid follicles per endoscopic visible field in the transverse colon ( P = 0.020). The presence of lymphoid hyperplasia is a frequent finding during colonoscopy. It may indicate an enhanced immunological mucosal response to antigenic stimulation such as GMA or infection.

BACKGROUND AND STUDY AIMS: Patients with gastroesophageal reflux disease are subdivided into non-erosive (NERD) and erosive reflux disease (ERD). The newly available EPKi processor enables high-definition resolution above HDTV standard (HD+). The aim of the study was to test the efficacy of HD+ esophagogastroduodenoscopy alone and in conjunction with i-Scan (newly developed postprocessing digital filter) and chromoendoscopy (Lugol’s solution) for differentiation of reflux patients. METHODS: The distal esophagus of patients with heartburn was inspected with three imaging modalities. HD+ was followed by i-Scan and 15-mL Lugol’s solution (1.5 %). The esophagus was evaluated for mucosal breaks (Los Angeles Classification [LA]). Small visible changes were also characterized, and targeted biopsies were performed. End points of the study were the presence and grade of esophagitis and the number of circumscribed changes. RESULTS: A total of 50 patients were included (female 29; mean age 54.7 years). HD+ identified nine patients with mucosal breaks (LA 7A; 2C), i-Scan was able to detect 12 patients (LA 8A; 2B; 2C; 0D) ( P = n. s.) and chromoendoscopy identified 25 patients (LA 16A; 7B; 1C, 1D) ( P < 0.01). Furthermore, a higher grade of esophagitis was recognized by using i-Scan and Lugol’s solution in 19 patients. The number of circumscribed lesions could be increased from 21 (HD+) to 58 (i-Scan) ( P < 0.01), and up to 85 after Lugol spraying ( P < 0.01). CONCLUSIONS: Lugol’s solution in conjunction with HD+ endoscopy significantly improves the identification of patients with esophagitis and reduces misclassification. The i-Scan filter and chromoendoscopy help to identify reflux-associated lesions.

Background and study aims Confocal endomicroscopy is a unique novel tool for in vivo histology in humans. Due to limitations imposed by the form of the equipment and by sterilization workflows, its use has been limited to the gastrointestinal tract so far. We have developed a rigid miniaturized probe for confocal endomicroscopy of the human liver during laparoscopy. Patients and methods To assess the feasibility and potential clinical value of this new system (diameter 6.3 mm), 25 patients with liver disease were examined during routine minilaparoscopy under conscious sedation. Results Subsurface serial images (from surface to 250 microm) were generated in real time after fluorescein injection, permitting visualization of hepatocytes, bile ducts, sinusoids, and collagen fibers in vivo. Typical appearances of liver diseases were identified. Confocal diagnosis of moderate-to-severe steatosis and pericellular fibrosis correlated well with histopathologic analysis of subsequent biopsies (83.3 % and 84.6 %, respectively). In addition, intra-abdominal structures such as gallbladder, omentum, and stomach were analyzed by endomicroscopy. Conclusions A miniaturized imaging system for confocal laparoscopy allowed in vivo microscopic analysis of healthy and diseased human liver for the first time during ongoing minilaparoscopy. Although such in vivo imaging does not yet compete with conventional histopathology, this novel confocal laparoscopy system may be of future relevance for immediate morphodynamic analysis in liver disease and the targeting of biopsies in vivo.

Biliary diseases such as cholangitis may cause jaundice and liver damage. Here, we report on an unusual cause of jaundice in an 84-year-old man 9 years after cholecystectomy. Ultrasound analysis revealed unclear extrahepatic cholestasis and subsequent ERCP showed a large biliary stone sourrounding a T-tube fragment that had remained in the common bile duct for more than 9 years after surgery. The tip of the drainage and the stone could be successfully removed using Dormia baskets. This case suggests that plastic material accidentally left in the common bile duct favours the development of large biliary casts when present over long periods of time.

BACKGROUND AND STUDY AIMS: Chromoendoscopy using methylene blue is employed in the gastrointestinal tract to delineate neoplastic lesions. We tested the value of chromoendoscopy during choledochoscopy for characterization of local inflammation, neoplasias, and other alterations in patients with biliary strictures. METHODS: Patients with suspected biliary lesions were scheduled for endoscopic retrograde cholangiography with subsequent cholangioscopy. After initial inspection of the bile duct, 15 ml methylene blue (0.1 %) was administered via the working channel of the cholangioscope. Newly appearing circumscribed or unstained lesions were judged according to their macroscopic type and staining features. Methylene-blue-aided diagnosis was compared with either clinical follow-up of the patients or, in some cases, with the results of targeted biopsies. RESULTS: A total of 55 patients [biliary stenosis/cholestasis of unknown origin (n = 24), stenosis after orthotopic liver transplantation (n = 11), primary sclerosing cholangitis (n = 20)] were included. Methylene blue unmasked subtle mucosal changes and permitted macroscopic characterization of circumscribed lesions. Characteristic surface staining patterns were seen in chronic inflammation, dysplasia, and ischemic-type biliary lesions. Nondysplastic mucosa appeared homogeneously stained, whereas scarred strictures showed a weak uptake of methylene blue. CONCLUSION: In this prospective feasibility study, methylene-blue-aided cholangioscopy was used for the first time to define different staining patterns of the bile duct. The differences in staining patterns identified normal, dysplastic, and inflamed mucosa of the bile duct, as was proved by follow-up or, in some cases, histology. Whereas homogeneous staining predicted the presence of normal mucosa, absence of staining of circumscribed lesions, or diffused staining of such lesions, represented neoplastic changes or inflammation.

For in-vivo diagnostics of cancer and pre-cancer in the stomach, there is no endoscopic procedure offering both high sensitivity and high specificity. Our data suggest that multispectral or hyperspectral imaging may be helpful to solve this problem. It is successfully applied to the detection and analysis of easily reachable carcinomas, ex-vivo samples of hollow organ mucosal carcinomas and also histological samples. An endoscopy system which allows flexible multispectral videoendoscopy for in-vivo diagnostics has so far been unavailable. To overcome this problem, we modified a standard Olympus endoscopy system to conduct in-vivo multispectral imaging of the upper GI tract. The pilot study is performed on 14 patients with adeno carcinomas in the stomach. For analysis, Support Vector Machine with linear and Gaussian Kernel, AdaBoost, RobustBoost and Random-Forest-walk are used and compared for the data classification with a leave-one-out strategy. The margin of the carcinoma for the training of the classifier is drawn by expert-labeling. The cancer findings are cross-checked by biopsies. We expect that the present study will help to improve the further development of hyperspectral endoscopy and to overcome some of the problems to be faced in this process.

A 28-year-old man was admitted to the emergency room of our hospital after syncope and acute gastrointestinal bleeding. On the basis of numerous oral and genital ulcerations as well as uveitis anterior and erythema nodosum, the diagnosis of Behcet's disease had been confirmed previously. The bleeding focus could not be detected by endoscopy. During the next days recurrent massive hemorrhages occurred in spite of immunosuppressive therapy with steroids. Angiography revealed a circumscribed bleeding source in the colon transversum near the left colonic flexure, which was treated by superselective coil embolization. A massive hemorrhage reoccurred and required a surgical approach with a Hartmann procedure. Histology depicted bleeding into the submucosa and mucosa and an ulcer in this area as well as lymphatic infiltration of the mucosa. Immunosuppressive therapy was intensified with azathioprine and resulted in a dramatic improvement of the oral and genital ulcers. In addition, no further gastrointestinal hemorrhage occurred. Due to its higher prevalence in patients from eastern Asia, Behcet's disease poses an important differential diagnosis of intestinal hemorrhage in patients of this descent.

Accurate detection of premalignant lesions and early cancers in the colon is essential for curative endoscopic or surgical therapy, since the prognosis for the affected patients is closely related to the size and stage of the neoplastic lesion. Total colonoscopy is the accepted gold standard for screening and surveillance of colorectal cancer. This review summarizes recently published diagnostic developments and key findings in the areas of colonoscopy, colonic tumors, and inflammatory bowel diseases. Relevant findings have been reported for chromo-endoscopy in the diagnosis of colitis-associated neoplasia, as well as flat and depressed adenomas. Real-time Doppler capabilities have now been added to endoscopic optical coherence tomography; the results of large-scale testing of narrow-band imaging endoscopy in the colon are being awaited; and fluorescence imaging has recently been added to the facilities available in video endoscopy. Most importantly, endomicroscopy now for the first time allows single-cell subsurface imaging during ongoing colonoscopy procedures, opening the way to in-vivo molecular and functional imaging.

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.