Diagnostic accuracy of probe-based confocal laser endomicroscopy in detecting residual colorectal neoplasia after EMR: a prospective study

Advancements in Neurosurgical Intraoperative Histology

Despite their relatively low incidence globally, central nervous system (CNS) tumors remain amongst the most lethal cancers, with only a few other malignancies surpassing them in 5-year mortality rates. Treatment decisions for brain tumors heavily rely on histopathological analysis, particularly intraoperatively, to guide surgical interventions and optimize patient outcomes. Frozen sectioning has emerged as a vital intraoperative technique, allowing for highly accurate, rapid analysis of tissue samples, although it poses challenges regarding interpretive errors and tissue distortion. Raman histology, based on Raman spectroscopy, has shown great promise in providing label-free, molecular information for accurate intraoperative diagnosis, aiding in tumor resection and the identification of neurodegenerative disease. Techniques including Stimulated Raman Scattering (SRS), Coherent Anti-Stokes Raman Scattering (CARS), Surface-Enhanced Raman Scattering (SERS), and Tip-Enhanced Raman Scattering (TERS) have profoundly enhanced the speed and resolution of Raman imaging. Similarly, Confocal Laser Endomicroscopy (CLE) allows for real-time imaging and the rapid intraoperative histologic evaluation of specimens. While CLE is primarily utilized in gastrointestinal procedures, its application in neurosurgery is promising, particularly in the context of gliomas and meningiomas. This review focuses on discussing the immense progress in intraoperative histology within neurosurgery and provides insight into the impact of these advancements on enhancing patient outcomes.

Advances in Pediatric Diagnostic Endoscopy: A State-of-the-Art Review

Pediatric endoscopy has revolutionized the way we diagnose and treat gastrointestinal disorders in children. Technological advances in computer processing and imaging continue to affect endoscopic equipment and advance diagnostic tools for pediatric endoscopy. Although commonly used by adult gastroenterologists, modalities, such as endomicroscopy, image-enhanced endoscopy, and impedance planimetry, are not routinely used in pediatric gastroenterology. This state-of-the-art review describes advances in diagnostic modalities, including image-enhanced endoscopy, confocal laser endomicroscopy, optical coherence tomography, endo functional luminal imaging probes, wireless motility/pH capsule, wireless colon capsule endoscopy, endoscopic ultrasound, and discusses the basic principles of each technology, including adult indications and pediatric applications, safety cost, and training data.

Confocal laser endomicroscopy in gastro-intestinal endoscopy: technical aspects and clinical applications

Confocal laser endomicroscopy (CLE) is an advanced endoscopic imaging technology that provides a magnified, cellular level view of gastrointestinal epithelia. In conjunction with topical or intravenous fluorescent dyes, CLE allows for an "optical biopsy" for real-time diagnosis. Two different CLE system have been used in clinical endoscopy, probe-based CLE (pCLE) and endoscope-based CLE (eCLE). Using pCLE, the device can be delivered: (I) into the luminal gastrointestinal tract through the working channel of standard endoscopes; (II) into extraluminal cystic and solid parenchymal lesions through an endoscopic ultrasound (EUS) needle; or (III) into the biliary system through an endoscopic retrograde cholangiopancreatography (ERCP) accessory channel. With eCLE, the probe is directly integrated into the tip of a conventional endoscope, however, these endoscopes are no longer commercially available. CLE has moderate to high diagnostic accuracy for neoplastic and inflammatory conditions through the gastrointestinal tract including: oesophageal, gastric and colonic neoplasia, pancreatic cysts and solid lesions, malignant pancreatobiliary strictures and inflammatory bowel disease. Some studies have demonstrated the diagnostic benefit of CLE imaging when combined with either conventional white light endoscopy or advanced imaging technologies. Therefore, optical biopsies using CLE can resolve diagnostic dilemmas in some cases where conventional imaging fails to achieve conclusive results. CLE could also reduce the requirement for extensive tissue sampling during surveillance procedures. In the future, CLE in combination with molecular probes, could allow for the molecular characterization of diseases and assess response to targeted therapy. However, the narrow field of view, high capital costs and specialized operator training requirements remain the main limitations. Future multi-center, randomized trials with a focus on conventional diagnostic applications, cost-effectiveness and standardized training will be required for definitive evidence. The objective of this review is to evaluate the technical aspects and current applications of CLE in patients with gastrointestinal and pancreatobiliary diseases and discuss future directions for this technique.

Classification of the Confocal Microscopy Images of Colorectal Tumor and Inflammatory Colitis Mucosa Tissue Using Deep Learning

Confocal microscopy image analysis is a useful method for neoplasm diagnosis. Many ambiguous cases are difficult to distinguish with the naked eye, thus leading to high inter-observer variability and significant time investments for learning this method. We aimed to develop a deep learning-based neoplasm classification model that classifies confocal microscopy images of 10× magnified colon tissues into three classes: neoplasm, inflammation, and normal tissue. ResNet50 with data augmentation and transfer learning approaches was used to efficiently train the model with limited training data. A class activation map was generated by using global average pooling to confirm which areas had a major effect on the classification. The proposed method achieved an accuracy of 81%, which was 14.05% more accurate than three machine learning-based methods and 22.6% better than the predictions made by four endoscopists. ResNet50 with data augmentation and transfer learning can be utilized to effectively identify neoplasm, inflammation, and normal tissue in confocal microscopy images. The proposed method outperformed three machine learning-based methods and identified the area that had a major influence on the results. Inter-observer variability and the time required for learning can be reduced if the proposed model is used with confocal microscopy image analysis for diagnosis.

Endoscopic molecular imaging in inflammatory bowel disease

Molecular imaging is a technique for imaging the processes occurring in a living body at a molecular level in real-time, combining molecular cell biology with advanced imaging technologies using molecular probes and fluorescence. Gastrointestinal endoscopic molecular imaging shows great promise for improving the identification of neoplasms, providing characterization for patient stratification and assessing the response to molecular targeted therapy. In inflammatory bowel disease, endoscopic molecular imaging can be used to assess disease severity and predict therapeutic response and prognosis. Endoscopic molecular imaging is also able to visualize dysplasia in the presence of background inflammation. Several preclinical and clinical trials have evaluated endoscopic molecular imaging; however, this area is just beginning to evolve, and many issues have not been solved yet. In the future, it is expected that endoscopic molecular imaging will be of increasing interest among clinicians as a new technology for the identification and evaluation of colorectal neoplasm and colitis-associated cancer.

Narrow-band imaging for scar (NBI-SCAR) classification: from conception to multicenter validation

BACKGROUND AND AIMS

Surveillance post-endoscopic resection (ER) currently warrants biopsy samples from the resection site scar in most cases, although clinical practice is variable. A classification with standard criteria for scars has not yet been established. We aimed to create and validate a novel classification for post-ER scars by using specific criteria based on advanced imaging.

METHODS

Key endoscopic features for scars with and without recurrence were (1) dark brown color, elongated/branched pit pattern, and dense capillary pattern and (2) whitish, pale appearance, round/slightly large pits, and irregular sparse vessels. Scars were first assessed with high-definition white-light endoscopy (HD-WLE) followed by interrogation with narrow-band imaging (NBI). Scars with at least 2 concordant characteristics were diagnosed with "high confidence" for NBI for scar (NBI-SCAR) classification. The final endoscopic predictions were correlated with histopathology. The primary outcome was the difference in sensitivity between NBI-SCAR and HD-WLE predictions. Secondary outcomes included the validation of our findings in 6 different endoscopy settings (Australia, United States, Japan, Brazil, Singapore, and Malaysia). The validation took place in 2 sessions separated by 2 to 3 weeks, each with 10 one-minute videos of post-ER scars on underwater NBI with dual focus. Inter-rater and intrarater reliability were calculated with Fleiss' free-marginal kappa and Bennett et al. S score, respectively.

RESULTS

One hundred scars from 82 patients were included. Ninety-five scars were accurately predicted with high confidence by NBI-SCAR in the exploratory phase. NBI-SCAR sensitivity was significantly higher compared with HD-WLE (100% vs 73.7%, P < .05). In the validation phase, similar results were found for endoscopists who routinely perform colonoscopies and use NBI (sensitivity of 96.4%). The inter-rater and intrarater reliability throughout all centers were, respectively, substantial (κ = .61) and moderate (average S = .52) for this subset.

CONCLUSIONS

NBI-SCAR has a high sensitivity and negative predictive value for excluding recurrence for endoscopists experienced in colonoscopy and NBI. In this setting, this approach may help to accurately evaluate or resect scars and potentially mitigate the burden of unnecessary biopsy samples.

Endoscopic scar assessment after colorectal endoscopic mucosal resection scars: when is biopsy necessary (EMR Scar Assessment Project for Endoscope (ESCAPE) trial)

OBJECTIVE

It is unclear whether endoscopic assessment of scars after colorectal endoscopic mucosal resection (EMR) has to include biopsies, even if endoscopy is negative. Vice versa, endoscopic diagnosis of recurrent adenoma may not require biopsy before endoscopic reinterventions. We prospectively analysed various endoscopic modalities in the diagnosis of recurrence following EMR.

DESIGN

We conducted a prospective study of patients undergoing colonoscopy after EMR of large (≥20 mm) colorectal neoplasia. Endoscopists predicted recurrence and confidence level with four imaging modes: high-definition white light (WL) and narrow-band imaging (NBI) with and without near focus (NF). Separately, 26 experienced endoscopists assessed offline images.

RESULTS

Two hundred and thirty patients with 255 EMR scars were included. The prevalence of recurrent adenoma was 24%. Diagnostic values were high for all modes (negative predictive value (NPV) ≥97%, positive predictive value (PPV) ≥81%, sensitivity ≥90%, specificity ≥93% and accuracy ≥93%). In high-confidence cases, NBI with NF had NPV of 100% (95% CI 98% to 100%) and sensitivity of 100% (95% CI 93% to 100%). Use of clips at initial EMR increased diagnostic inaccuracy (adjusted OR=1.68(95% CI 1.01 to 2.75)). In offline assessment, specificity was high for all imaging modes (mean: ≥93% (range: 55%-100%)), while sensitivity was significantly higher for NBI-NF (82%(72%-93%)%)) compared with WL (69%(38%-86%); p<0.001), WL-NF (68%(55%-83%); p<0.001) and NBI (71%(59%-90%); p<0.001).

CONCLUSION

Our study demonstrates very high sensitivity and accuracy for all four imaging modalities, especially NBI with NF, for diagnosis of recurrent neoplasia after EMR. Our data strongly suggest that in cases of high confidence negative optical diagnosis based on NBI-NF, no biopsy is needed to confirm absence of recurrence during colorectal EMR follow-up. A high confidence positive optical diagnosis can lead to immediate resection of any suspicious area. In all cases of low confidence, biopsy is still required.

TRIAL REGISTRATION NUMBER

NCT02668198.

The Probe Based Confocal Laser Endomicroscopy (pCLE) in Locally Advanced Gastric Cancer: A Powerful Technique for Real-Time Analysis of Vasculature

Probe based confocal laser endomicroscopy (pCLE) is an advanced technique which provides imaging of gastrointestinal mucosa at subcellular resolution and, importantly, a valid tool for the evaluation of microvasculature during endoscopic examination. In order to assess intratumoral vascularization and the efficiency of blood flow in locally advanced gastric cancer, we examined 57 patients through pCLE imaging. The vascular alterations in gastric cancer were mainly characterized by leakage and by the presence of tortuous and large size vessels. Defects in blood flow were detected very rarely. No association between the angiogenic score and the gastric tumor site or histological type was observed. Interestingly, no correlation was also found with the tumor grading indicating that the vascular angiogenic anomalies in gastric cancer represent an early pathological event to be observed and detected. The majority of patients displayed unchanged vascular alterations following neoadjuvant chemotherapy and this positively correlated with stable or progressive disease, suggesting that an unaltered angiogenic score could per se be indicative of poor therapeutic efficacy. Different vascular parameters were evaluated by immunofluorescence using bioptic samples and the vessel density did not correlate with clinical staging, site or histologic type. Interestingly, only CD105, Multimerin-2 and GLUT1 were able to discriminate normal from tumoral gastric mucosa. Taken together, these findings indicate that functional and structural angiogenic parameters characteristic of tumor blood network were fully detectable by pCLE. Moreover, the evaluation of tumor vasculature by real-time assessment may provide useful information to achieve tailored therapeutic interventions for gastric cancer patients.

New intraoperative imaging technologies: Innovating the surgeon's eye toward surgical precision

Imaging is one of the pillars for the ongoing evolution of surgical oncology toward a precision paradigm. In the present overview, some established or emerging intraoperative imaging technologies are described in light of the vision and experience of our group in image-guided surgery, focusing on digestive surgical oncology.

Feasibility of real-time intestinal bloodstream evaluation using probe-based confocal laser endomicroscopy in a porcine intestinal ischemia model

BACKGROUND

Intestinal ischemia can lead to fatal complications if left unrecognized during surgery. The current techniques of intraoperative microvascular assessment remain subjective. Probe-based confocal laser endomicroscopy (pCLE) has the potential to objectively evaluate microvascular blood flow in real-time setting. The present study evaluated the technical feasibility of real-time intestinal bloodstream evaluation using pCLE in a porcine intestinal ischemia model.

METHODS

Seven pigs were used. The intestinal ischemia model was prepared by sequentially dividing the mesenteric blood vessels. The intestinal bloodstream was evaluated on its serosal surface using pCLE (Cellvizio 488 probe, Ultra Mini O) at every 1-cm segment from a vessel-preservation border (i.e., the cut end of the vessel). Images of the blood vessels and flow of red blood cells (RBCs) in each visualized vessel were semi-qualitatively assessed using a 3-scale scoring system. In addition, 25 surgeons blindly assessed the 10 movies recorded at 0, 1, 2, 3, and 5 cm from a vessel-preservation border using a 4-scale scoring system to confirm the consistency of the evaluation of the pCLE system.

RESULTS

Images of the blood vessels were successfully obtained from the cut end of the vessel to the segment 4 cm away. Good unidirectional flow of RBCs was observed from the cut end to the 2-cm segment, whereas the flow became bidirectional between 2 and 3 cm segments. Beyond 4 cm, no flow images were obtained. The specimen obtained from the segment beyond 4 cm showed remarkable mucosal color change, which was confirmed as a necrotic change histologically. The evaluations from the cut end of the vessel to the segment 1 cm away by surgeons were excellent or good and it was almost consistent.

CONCLUSIONS

Real-time bloodstream evaluation using pCLE is feasible and potentially effective for predicting intestinal ischemia during surgery.

Development of a porcine model for assessment of mucosal repair following endoscopic resection of the lower gastrointestinal tract

BACKGROUND AND AIMS

 Endoscopic mucosal resection (EMR) is widely performed for the treatment of colorectal polyps. However, the pathophysiological mechanisms of mucosal repair, including in situations at high risk of post-polypectomy bleeding, remain largely unknown. The objective of our study was to develop a porcine model of EMR in the lower gastrointestinal tract to monitor mucosal wound healing over time.

METHODS

 Under general anesthesia, five large wounds were created in the lower gastrointestinal tract at different times, i. e. at day 0, 3, 7, 10, and 14, by multiband EMR, in each of the six pigs in the study. A colorectal resection was performed at day 14 and the animal euthanized. Repeated endoscopic and endomicroscopic examination, and histological analysis were performed.

RESULTS

 No complications occurred and all animals reached the study end point. The endoscopic aspect of wound healing evolved into different phases with first a fibrin deposit covering the wounds which then gave way to granulomatous tissue. The size of the wound regressed significantly as early as day 3. Re-epithelialization of the wound started from day 7, and neo-mucosal crypts appeared from day 10. The endomicroscopic analysis described a 'ground glass appearance' from day 3 and irregular crypts from day 10, which was consistent with histological data. Good agreement between macroscopic, endomicroscopic, and histological parameters of mucosal wound healing was observed in vivo.

CONCLUSION

 This study demonstrates for the first time the feasibility of an experimental in vivo porcine model of lower gastrointestinal endoscopic resections to monitor tissue repair. This model might be helpful to document pharmacological approaches for preventing complications of endoscopic procedures performed in humans.

Optical improvements in the diagnosis of bladder cancer: implications for clinical practice

Background

For over 100 years white-light cystoscopy has remained the gold-standard technique for the detection of bladder cancer (BCa). Some limitations in the detection of flat lesions (CIS), the differentiation between inflammation and malignancy, the inaccurate determination of the tumor margin status as well as the tumor depth, have led to a variety of technological improvements. The aim of this review is to evaluate the impact of these improvements in the diagnosis of BCa and their effectiveness in clinical practice.

Methods

A systematic literature search was conducted according to the PRISMA statement to identify studies reporting on imaging modalities in the diagnosis of NMIBC between 2000 and 2017. A two-stage selection process was utilized to determine eligible studies. A total of 74 studies were considered for final analysis.

Results

Optical imaging technologies have emerged as an adjunct to white-light cystoscopy and can be classified according to their scope as macroscopic, microscopic and molecular. Macroscopic techniques including photodynamic diagnosis (PDD), narrow-band imaging (NBI) and the Storz Professional Image Enhancement System (IMAGE1 S, formerly known as SPIES) are similar to white-light cystoscopy, but are superior in the detection of bladder tumors by means of contrast enhancement. Especially the detection rate of very mute lesions in the bladder mucosa (CIS) could be significantly increased by the use of these methods. Microscopic imaging techniques like confocal laser endomicroscopy and optical coherence tomography permit a real-time high-resolution assessment of the bladder mucosa at a cellular and sub-cellular level with spatial resolutions similar to histology, enabling the surgeon to perform an 'optical biopsy'. Molecular techniques are based on the combination of optical imaging technologies with fluorescence labeling of cancer-specific molecular agents like antibodies. This labeling is intended to favor an optical distinction between benign and malignant tissue.

Conclusions

Optical improvements of the standard white-light cystoscopy have proven their benefit in the detection of BCa and have found their way into clinical practice. Especially the combination of macroscopic and microscopic techniques may improve diagnostic accuracy. Nevertheless, HAL-PDD guided cystoscopy is the only approach approved for routine use in the diagnosis of BCa by most urological associations in the EU and USA to date.

A standardized imaging protocol is accurate in detecting recurrence after EMR

BACKGROUND AND AIMS

EMR of large laterally spreading lesions (LSL) in the colon is a safe and effective alternative to surgery. Post-EMR scar assessment currently involves taking biopsy specimens of the scar to detect residual or recurrent adenoma (RRA). The accuracy of endoscopic imaging of the post-EMR scar is unknown. We aimed to determine the accuracy of a standardized imaging protocol in post-EMR scar assessment.

METHODS

Prospective, single-center data from the Australian Colonic EMR study were analyzed. Consecutive patients undergoing first surveillance colonoscopy (SC1) after EMR of a large LSL were eligible. All scars were sequentially examined with high-definition white light (HD-WL) and narrow-band imaging (NBI) in a standardized fashion and then biopsies were performed. Endoscopic recurrence (recurrence at the post-EMR scar detected by systematic endoscopic assessment) was compared with the histologic findings.

RESULTS

One hundred eighty-three post-EMR scars were included. Thirty of 183 (16.4%) were confirmed to have RRA histologically at SC1. Thirty-seven of 183 (20.2%) post-EMR scars demonstrated RRA endoscopically. The sensitivity and specificity of endoscopic RRA detection were 93.3% (95% confidence interval [CI], 77.9%-99.2%) and 94.1% (95% CI, 89.1%-97.3%), respectively. The positive predictive value was 75.7% (95% CI, 58.8%-88.2%) and the negative predictive value was 98.6% (95% CI, 95.1%-99.8%). The diagnostic accuracy was 94.0%. Sensitivity was higher for the combination of HD-WL and NBI as opposed to HD-WL alone (93.3% vs 66.7%). The specificity was high for both HD-WL and HD-WL + NBI (96.1% and 94.1%, respectively). Flat morphology of RRA was better seen with NBI (P = .002).

CONCLUSIONS

Endoscopic detection of RRA in the post-EMR scar is highly accurate using a standardized imaging protocol with HD-WL and NBI. This allows real-time, accurate detection of recurrence and its concurrent treatment, and raises the possibility that routine biopsy of the post-EMR scar may not be necessary.

Diagnostic accuracy of confocal laser endomicroscopy for the characterization of liver nodules

OBJECTIVES

Probe-based confocal laser endomicroscopy (pCLE) is a promising new imaging technique enabling in-vivo analysis of tissues at the cellular level, in real time. The aim of the present study was to prospectively evaluate the feasibility and accuracy of indocyanine green-aided pCLE for the diagnosis of malignant liver nodules.

PATIENTS AND METHODS

From October 2014 to July 2015, liver specimens from 30 consecutive patients were analyzed ex vivo using pCLE directly after resection, with indocyanine green as contrast agent. The final diagnosis was obtained histologically, as per standard of care. In phase 1, a pathologist and a physicist established pCLE image criteria to distinguish normal parenchyma, malignant nodules, and metastases that had completely responded to chemotherapy. In phase 2, a pathologist and a surgeon reviewed selected videos retrospectively to assess the effectiveness of these.

RESULTS

In phase 1, the healthy nodules were characterized by fluorescent hepatocytes with nonfluorescent nuclei and the malignant nodules were identified as strongly fluorescent, irregular cancer-cell clusters. The extracellular matrix was substantially less fluorescent compared with the cancerous clusters of cells. After chemotherapy, a very dense and strongly fluorescent fibrosis replaced tubular structures of cancerous cells. The retrospective evaluation in phase 2 resulted in 78 and 100% sensitivity, 100 and 89% specificity, 90 and 100% positive predictive value, and 90 and 100% negative predictive value for the surgeon and the pathologist, respectively, for the detection of malignant nodules.

CONCLUSION

This series emphasized that characterization of liver metastases is possible with pCLE, with high performance results.

Confocal Imaging and Tissue-Specific Fluorescent Probes for Real-Time In Vivo Immunohistochemistry. Proof of the Concept in a Gastric Lymph Node Metastasis Model

BACKGROUND

Tumor-specific fluorescent antibodies, which can be recognized at a cellular or tissue level using optical imaging such as confocal laser endomicroscopy (CLE), could provide a means for rapid and accurate tumor diagnosis and staging. The aim of this study was to evaluate the ability of CLE to detect the presence of tagged cells within lymph nodes in an original simulated metastatic model.

MATERIALS AND METHODS

A solution of indocyanine green containing a suspension of porcine hepatocytes, marked with carboxy-fluorescein-succinimidyl-ester (CFSE), was injected endoscopically in the gastric submucosa of 10 pigs. Fluorescence lymphography using a near-infrared laparoscope was used to identify sentinel and secondary drainage nodes. Additionally, a nonfluorescent gastric and a mesenteric node were identified. Every 5-10 min, those nodes were scanned using probe-based or needle-based CLE (pCLE or nCLE). Immunohistochemistry (IHC) using anti-cytokeratin 18 antibodies was subsequently performed to confirm the presence of hepatocytes in the lymph nodes.

RESULTS

A total of 36 lymph nodes were analyzed with both CLE probes. Hepatocyte penetration in lymph nodes, as assessed by repeated CLE scanning, took 10-40 min after submucosal injection. Concordance between CLE and IHC was 84 and 72 % for pCLE and nCLE, respectively. False negatives were partly due to incomplete CFSE labeling of hepatocytes, which could not be recognized by CLE, but were detected with IHC.

CONCLUSIONS

Real-time CLE analysis effectively recognized the presence in perigastric nodes of marked hepatic cells that had been injected endoscopically in the stomach. Validation studies on tumor-bearing animals using tumor-specific antibodies should be performed.

The influence of clips on scars after EMR: clip artifact

BACKGROUND AND AIMS

Laterally spreading lesions ≥20 mm are conventionally removed by EMR. Endoscopic clips are increasingly used to mitigate the risk of delayed bleeding. Clips may alter the endoscopic appearance of the scar after EMR, interfering with the assessment of adenoma recurrence. We aimed to evaluate this.

METHODS

Prospective, single-center data from the Australian Colonic Endoscopic resection study (January 2011-May 2015) were analyzed. Patients undergoing EMR of laterally spreading lesions with endoscopic clips used at the EMR defect were eligible. Data included patient and lesion characteristics and procedural, clinical, and histologic outcomes.

RESULTS

Clips were used in 111 of 885 lesions (12.5%). A total of 62 of 111 clipped lesions had standardized, high-definition, white light, and narrow-band images of the scars after EMR at first surveillance colonoscopy, and the patients were enrolled. Analysis of the images showed 4 situations: a bland scar (N = 27), residual adenoma (N = 6), mucosal elevation with normal pit pattern (N = 14), or granulation tissue related to the presence of residual clips (N = 15). The latter 2 entities were termed post-EMR scar clip artifact (ESCA). Overall, 29 of 62 previously clipped EMR sites (46.8%) had ESCA at a median follow-up of 5.2 months. Twenty scars had residual clips, and 15 of 20 (75.0%) showed ESCA (P = .002). Lesions clipped for prophylaxis of bleeding were more likely to show ESCA than those clipped for deep mural injury or intraprocedural bleeding (65.5% vs 41.7%; P = .006). ESCA was associated with female sex (P = .010) and greater age (P = .011).

CONCLUSIONS

ESCA is characterized by a nodular elevation of the mucosa with a normal pit pattern and can occur with or without residual clips. Prophylactic clip closure and the presence of residual clips are associated with ESCA. (

CLINICAL TRIAL REGISTRATION NUMBER

NCT01368289.).

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.

High-resolution handheld rigid endomicroscope based on full-field optical coherence tomography

Full-field optical coherence tomography (FF-OCT) is a powerful tool for nondestructive assessment of biological tissue, i.e., for the structural examination of tissue in depth at a cellular resolution. Mostly known as a microscopy device for ex vivo analysis, FF-OCT has also been adapted to endoscopy setups since it shows good potential for in situ cancer diagnosis and biopsy guidance. Nevertheless, all the attempts to perform endoscopic FF-OCT imaging did not go beyond lab setups. We describe here, to the best of our knowledge, the first handheld FF-OCT endoscope based on a tandem interferometry assembly using incoherent illumination. A common-path passive imaging interferometer at the tip of an optical probe makes it robust and insensitive to environmental perturbations, and a low finesse Fabry-Perot processing interferometer guarantees a compact system. A good resolution (2.7 μm transverse and 6 μm axial) is maintained through the long distance, small diameter relay optics of the probe, and a good signal-to-noise ratio is achieved in a limited 100 ms acquisition time. High-resolution images and a movie of a rat brain slice have been recorded by moving the contact endoscope over the surface of the sample, allowing for tissue microscopic exploration at 20 m under the surface. These promising ex vivo results open new perspectives for in vivo imaging of biological tissue, in particular, in the field of cancer and surgical margin assessment.

Application and Efficacy of Super-Magnifying Endoscopy for the Lower Intestinal Tract

Endoscopy plays a significant role in the diagnosis, management, and surveillance of colorectal cancer (CRC) and inflammatory bowel diseases (IBDs). Moreover, magnifying endoscopy and image-enhanced endoscopy has a crucial role in the clinical setting. Recently, a super-magnifying endoscope has been developed, and two devices, confocal laser endomicroscopy (CLE) and an endocytoscopy system (ECS), which allow in vivo microscopic inspection of the microstructural mucosal features of the gastrointestinal tract, are currently available. Studies on the use of ECS in CRC were reported by a Japanese group. Additionally, a few studies on the use of ECS in IBD have been reported. CLE has been shown to be reliable in assessing the activity of the disease in IBDs in both ulcerative colitis and Crohn's disease. Various published studies evaluated the use of CLE during colonoscopy to distinguish colorectal polyp pathology and neoplasia. However, these studies are heterogeneous, and further evidence is necessary to confirm the efficacy of CLE.

Intestinal Permeability in Inflammatory Bowel Disease: Pathogenesis, Clinical Evaluation, and Therapy of Leaky Gut

The pathogenesis of inflammatory bowel disease (IBD) is multifactorial with data suggesting the role of a disturbed interaction between the gut and the intestinal microbiota. A defective mucosal barrier may result in increased intestinal permeability which promotes the exposition to luminal content and triggers an immunological response that promotes intestinal inflammation. IBD patients display several defects in the many specialized components of mucosal barrier, from the mucus layer composition to the adhesion molecules that regulate paracellular permeability. These alterations may represent a primary dysfunction in Crohn's disease, but they may also perpetuate chronic mucosal inflammation in ulcerative colitis. In clinical practice, several studies have documented that changes in intestinal permeability can predict IBD course. Functional tests, such as the sugar absorption tests or the novel imaging technique using confocal laser endomicroscopy, allow an in vivo assessment of gut barrier integrity. Antitumor necrosis factor-α (TNF-α) therapy reduces mucosal inflammation and restores intestinal permeability in IBD patients. Butyrate, zinc, and some probiotics also ameliorate mucosal barrier dysfunction but their use is still limited and further studies are needed before considering permeability manipulation as a therapeutic target in IBD.

In-vivo microscopy in the diagnosis of intestinal neoplasia and inflammatory conditions

Confocal laser endomicroscopy (CLE) is a rapidly emerging tool in endoscopic imaging allowing in-vivo microscopy of examined gastrointestinal mucosa. This review will discuss the most recent advances of confocal laser endomicroscopy in the diagnosis of intestinal neoplasia and inflammatory conditions.

Self-illuminating quantum dots for non-invasive bioluminescence imaging of mammalian gametes

Background

The fertility performance of animals is still a mystery and the full comprehension of mammalian gametes maturation and early embryonic development remains to be elucidated. The recent development in nanotechnology offers a new opportunity for real-time study of reproductive cells in their physiological environments. As a first step toward that goal, we evaluated the effectiveness of a fluorescent and luminescent nanoparticle for in vitro and ex vivo imaging of porcine gametes.

Methods

Freshly harvested boar sperm were labeled with red-shifted (655 nm) quantum dot nanoparticles conjugated (QD+) or not (QD−) with plasminogen antibody and evaluated. Subsets of labeled spermatozoa were loaded into straws and placed within the lumen of gilt reproductive tracts for ex vivo intra-uterine imaging. Porcine cumulus-oocyte complexes (COCs) were matured in the presence of QD− or QD+. Ovarian follicles were microinjected with QD− or QD+ and placed in culture for up to 4 days. After labeling, all samples were supplemented with coelenterazine, the luciferase substrate, and immediately submitted to bioluminescence analysis, followed by fluorescence and hyperspectral imaging. Data were analyzed with ANOVA and P < 0.05 indicated significant differences.

Results

All labeled-samples revealed bioluminescence emission that was confirmed by fluorescence and hyperspectral imaging of the QD localization within the cells and tissues. Over 76% of spermatozoa and both immature and mature COCs were successfully labeled with QD− or QD+. The QD− fluorescence appeared homogenously distributed in the oocytes, while found in the entire sperm length with a higher accumulation within the mid-piece. Labeled-follicles exhibited a progressive migration of QD nanoparticles within the follicle wall during culture. In contrast, QD+ fluorescence signals appeared condensed and stronger in the follicle cells, sperm head, and sub-plasma membrane area of mature oocytes. Weaker QD+ signals were detected in the cumulus cells. Fluorescence and hyperspectral microscope imaging showed comparable intracellular QD localization. Ex-vivo intra-uterine bioluminescence imaging of labeled spermatozoa revealed stronger signals captured over the oviducts, with uterine body allowing the lowest signal detection.

Conclusion

Findings indicate that conjugated and non-conjugated fluorescent nanoparticles can be used for effective labeling of mammalian gametes for in vitro monitoring and potential in vivo targeted-imaging.

Electronic supplementary material

The online version of this article (doi:10.1186/s12951-015-0097-1) contains supplementary material, which is available to authorized users.

Use of probe-based confocal laser endomicroscopy (pCLE) in gastrointestinal applications. A consensus report based on clinical evidence

BACKGROUND

Probe-based confocal laser endomicroscopy (pCLE) provides microscopic imaging during an endoscopic procedure. Its introduction as a standard modality in gastroenterology has brought significant progress in management strategies, affecting many aspects of clinical care and requiring standardisation of practice and training.

OBJECTIVE

This study aimed to provide guidance on the standardisation of its practice and training in Barrett's oesophagus, biliary strictures, colorectal lesions and inflammatory bowel diseases.

METHODS

Initial statements were developed by five group leaders, based on the available clinical evidence. These statements were then voted and edited by the 26 participants, using a modified Delphi approach. After two rounds of votes, statements were validated if the threshold of agreement was higher than 75%.

RESULTS

Twenty-six experts participated and, among a total of 77 statements, 61 were adopted (79%) and 16 were rejected (21%). The adoption of each statement was justified by the grade of evidence.

CONCLUSION

pCLE should be used to enhance the diagnostic arsenal in the evaluation of these indications, by providing microscopic information which improves the diagnostic performance of the physician. In order actually to implement this technology in the clinical routine, and to ensure good practice, standardised initial and continuing institutional training programmes should be established.

Diagnosis of pancreatic cysts: EUS-guided, through-the-needle confocal laser-induced endomicroscopy and cystoscopy trial: DETECT study

BACKGROUND

The diagnosis of pancreatic cystic neoplasms (PCNs), which now depends on morphology, cytology, and fluid analysis, is still challenging. A novel confocal laser endomicroscopy probe that can be inserted through a 19-gauge FNA needle allows needle-based confocal laser endomicroscopy (nCLE), and the feasibility of nCLE has been reported in PCNs. The combination of cystoscopy by using a through-the-needle fiberoptic probe in combination with nCLE under EUS guidance may improve the diagnosis of PCNs.

OBJECTIVE

To assess the feasibility, safety, and diagnostic yield of the combination of cystoscopy and nCLE in the clinical diagnosis of PCNs.

DESIGN

A prospective feasibility study.

SETTING

An academic tertiary referral center.

PATIENTS

Thirty patients with PCNs.

INTERVENTIONS

EUS-guided dual through-the-needle imaging (cystoscopy and nCLE) for PCNs.

MAIN OUTCOME MEASUREMENTS

Technical feasibility and safety. Associations of cystoscopy and nCLE findings with clinical diagnosis of PCNs.

RESULTS

The procedure was technically successful with the exception of 1 probe exchange failure. In 2 patients (7%), postprocedure pancreatitis developed. Specific features associated with the clinical diagnosis of mucinous cysts were identified: mucin on cystoscopy and papillary projections and dark rings on nCLE. The sensitivity of cystoscopy was 90% (9/10), and that of nCLE was 80% (8/10), and the combination was 100% (10/10) in 18 high-certainty patients.

LIMITATIONS

A single-center study and lack of complete pathologic correlation.

CONCLUSION

The combination of dual through-the-needle imaging (cystoscopy and nCLE) of pancreatic cysts appears to have strong concordance with the clinical diagnosis of PCN. (

CLINICAL TRIAL REGISTRATION NUMBER

NCT01447238.).

Endoscopic imaging

OPINION STATEMENT

The most important tools are the eye and the brain. A detailed white-light high-resolution examination and ability to recognize subtle lesions provide the foundation of the ability to detect lesions in the gastrointestinal tract. Novel technologies are now available to provide additional information with the goals of detection, delineation, or classification often with a focus on neoplasia in the gastrointestinal tract. The observer using these new tools must still recognize, interpret, and then make a clinically relevant conclusion. Therefore, the assessment of these tools may focus on both the technical feasibility to use the respective equipment to obtain an image and then also the associated cognitive-based criteria for image interpretation.

State of the art in advanced endoscopic imaging for the detection and evaluation of dysplasia and early cancer of the gastrointestinal tract

Ideally, endoscopists should be able to detect, characterize, and confirm the nature of a lesion at the bedside, minimizing uncertainties and targeting biopsies and resections only where necessary. However, under conventional white-light inspection – at present, the sole established technique available to most of humanity – premalignant conditions and early cancers can frequently escape detection. In recent years, a range of innovative techniques have entered the endoscopic arena due to their ability to enhance the contrast of diseased tissue regions beyond what is inherently possible with standard white-light endoscopy equipment. The aim of this review is to provide an overview of the state-of-the-art advanced endoscopic imaging techniques available for clinical use that are impacting the way precancerous and neoplastic lesions of the gastrointestinal tract are currently detected and characterized at endoscopy. The basic instrumentation and the physics behind each method, followed by the most influential clinical experience, are described. High-definition endoscopy, with or without optical magnification, has contributed to higher detection rates compared with white-light endoscopy alone and has now replaced ordinary equipment in daily practice. Contrast-enhancement techniques, whether dye-based or computed, have been combined with white-light endoscopy to further improve its accuracy, but histology is still required to clarify the diagnosis. Optical microscopy techniques such as confocal laser endomicroscopy and endocytoscopy enable in vivo histology during endoscopy; however, although of invaluable assistance for tissue characterization, they have not yet made transition between research and clinical use. It is still unknown which approach or combination of techniques offers the best potential. The optimal method will entail the ability to survey wide areas of tissue in concert with the ability to obtain the degree of detailed information provided by microscopic techniques. In this respect, the challenging combination of autofluorescence imaging and confocal endomicroscopy seems promising, and further research is awaited.

Confocal laser endomicroscopy in gastrointestinal and pancreatobiliary diseases

Confocal laser endomicroscopy (CLE) is an emerging diagnostic procedure that enables in vivo pathological evaluation during ongoing endoscopy. There are two types of CLE: endoscope-based CLE (eCLE), which is integrated in the tip of the endoscope, and probe-based CLE (pCLE), which goes through the accessory channel of the endoscope. Clinical data of CLE have been reported mainly in gastrointestinal (GI) diseases including Barrett's esophagus, gastric neoplasms, and colon polyps, but, recently, a smaller pCLE, which goes through a catheter or a fine-needle aspiration needle, was developed and clinical data in the diagnosis of biliary stricture or pancreatic cysts have been increasingly reported. The future application of this novel technique expands beyond the pathological diagnosis to functional or molecular imaging. Despite these promising data, the generalizability of the procedure should be confirmed especially in Japan and other Asian countries, where the current diagnostic yield for GI luminal diseases is high. Given the high cost of CLE devices, cost-benefit analysis should also be considered.

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.

Optical molecular imaging for diagnosing intestinal diseases

Real-time visualization of the molecular signature of cells can be achieved with advanced targeted imaging techniques using molecular probes and fluorescence endoscopy. This molecular optical imaging in gastrointestinal endoscopy is promising for improving the detection of neoplastic lesions, their characterization for patient stratification, and the assessment of their response to molecular targeted therapy and radiotherapy. In inflammatory bowel disease, this method can be used to detect dysplasia in the presence of background inflammation and to visualize inflammatory molecular targets for assessing disease severity and prognosis. Several preclinical and clinical trials have applied this method in endoscopy; however, this field has just started to evolve. Hence, many problems have yet to be solved to enable the clinical application of this novel method.

Optical molecular imaging in the gastrointestinal tract

Recent developments in optical molecular imaging allow for real-time identification of morphologic and biochemical changes in tissue associated with gastrointestinal neoplasia. This review summarizes widefield and high-resolution imaging modalities in preclinical and clinical evaluation for the detection of colorectal cancer and esophageal cancer. Widefield techniques discussed include high-definition white light endoscopy, narrow band imaging, autofluoresence imaging, and chromoendoscopy; high-resolution techniques discussed include probe-based confocal laser endomicroscopy, high-resolution microendoscopy, and optical coherence tomography. New approaches to enhance image contrast using vital dyes and molecular-specific targeted contrast agents are evaluated.

Progress in molecular imaging in endoscopy and endomicroscopy for cancer imaging

Imaging is an essential tool for effective cancer management. Endoscopes are important medical instruments for performing in vivo imaging in hollow organs. Early detection of cancer can be achieved with surveillance using endoscopy, and has been shown to reduce mortality and to improve outcomes. Recently, great advancements have been made in endoscopic instruments, including new developments in optical designs, light sources, optical fibers, miniature scanners, and multimodal systems, allowing for improved resolution, greater tissue penetration, and multispectral imaging. In addition, progress has been made in the development of highly-specific optical probes, allowing for improved specificity for molecular targets. Integration of these new endoscopic instruments with molecular probes provides a unique opportunity for significantly improving patient outcomes and has potential to further improve early detection, image guided therapy, targeted therapy, and personalized medicine. This work summarizes current and evolving endoscopic technologies, and provides an overview of various promising optical molecular probes.

Multicenter, randomized, controlled trial of confocal laser endomicroscopy assessment of residual metaplasia after mucosal ablation or resection of GI neoplasia in Barrett's esophagus

BACKGROUND

Endoscopic ablation is an accepted standard for neoplasia in Barrett's esophagus (BE). Eradication of all glandular mucosa in the distal esophagus cannot be reliably determined at endoscopy.

OBJECTIVE

To assess if use of probe-based confocal laser endomicroscopy (pCLE) in addition to high-definition white light (HDWL) could aid in determination of residual BE.

DESIGN

Prospective, multicenter, randomized, clinical trial.

SETTING

Academic medical centers.

PATIENTS

Patients with Barrett's esophagus undergoing ablation.

INTERVENTION

After an initial attempt at ablation, patients were followed-up either with HDWL endoscopy or HDWL plus pCLE, with treatment of residual metaplasia or neoplasia based on endoscopic findings and pCLE used to avoid overtreatment.

MAIN OUTCOME MEASUREMENTS

The proportion of optimally treated patients, defined as those with residual BE who were treated and had complete ablation plus those without BE who were not treated and had no evidence of disease at follow-up.

RESULTS

The study was halted at the planned interim analysis based on a priori criteria. After enrollment was halted, all patients who had been randomized were followed to study completion. Among the 119 patients with follow-up, there was no difference in the proportion of patients achieving optimal outcomes in the two groups (15/57, 26% for HDWL; 17/62, 27% with HDWL + pCLE). Other outcomes were similar in the two groups.

LIMITATIONS

The study was closed after the interim analysis due to low conditional power resulting from lack of difference between groups as well as higher-than-expected residual Barrett's esophagus in both arms.

CONCLUSION

This study yields no evidence that the addition of pCLE to HDWL imaging for detection of residual Barrett's esophagus or neoplasia can provide improved treatment.