Confocal Laser Endomicroscopy System Research Articles

384 Characterization of Ex Vivo and In Vivo Intraoperative Neurosurgical Confocal Laser Endomicroscopy Imaging

INTRODUCTION: The new FDA-cleared fluorescein sodium (FNa)-based confocal laser endomicroscopy (CLE) imaging system allows for intraoperative on-the-fly cellular level imaging. Two feasibility studies have been completed with intraoperative use of this CLE system in ex vivo and in vivo modalities. METHODS: Images acquired from two prospective CLE clinical studies, one ex vivo and one in vivo, were analyzed quantitatively. Two image quality parameters – brightness and contrast – were measured using Fiji software and compared between ex vivo and in vivo images for imaging timing from FNa dose and in glioma, meningioma, and intracranial metastatic tumor cases. The diagnostic performance of the two studies was compared. RESULTS: Overall, the in vivo images have higher brightness and contrast than the ex vivo images (p < 0.001). A weak negative correlation exists between image quality and timing of imaging after FNa dose for the ex vivo images, but not the in vivo images. In vivo images have higher brightness and contrast than ex vivo images acquired after FNa redosing. In vivo images have higher image quality than ex vivo images (p < 0.001) in glioma, meningioma, and intracranial metastatic tumor cases. In vivo imaging yielded higher sensitivity (90% vs. 72%) and negative predictive value (81% vs 38%) than ex vivo imaging. CONCLUSIONS: In our setting, in vivo CLE optical biopsy outperforms ex vivo CLE by producing higher quality images and less image deterioration, leading to better diagnostic performance. These results support the in vivo modality as the modality of choice for intraoperative CLE imaging.

Characterization of ex vivo and in vivo intraoperative neurosurgical confocal laser endomicroscopy imaging.

BackgroundThe new US Food and Drug Administration-cleared fluorescein sodium (FNa)-based confocal laser endomicroscopy (CLE) imaging system allows for intraoperative on-the-fly cellular level imaging. Two feasibility studies have been completed with intraoperative use of this CLE system in ex vivo and in vivo modalities. This study quantitatively compares the image quality and diagnostic performance of ex vivo and in vivo CLE imaging.MethodsImages acquired from two prospective CLE clinical studies, one ex vivo and one in vivo, were analyzed quantitatively. Two image quality parameters – brightness and contrast – were measured using Fiji software and compared between ex vivo and in vivo images for imaging timing from FNa dose and in glioma, meningioma, and intracranial metastatic tumor cases. The diagnostic performance of the two studies was compared.ResultsOverall, the in vivo images have higher brightness and contrast than the ex vivo images (p < 0.001). A weak negative correlation exists between image quality and timing of imaging after FNa dose for the ex vivo images, but not the in vivo images. In vivo images have higher image quality than ex vivo images (p < 0.001) in glioma, meningioma, and intracranial metastatic tumor cases. In vivo imaging yielded higher sensitivity and negative predictive value than ex vivo imaging.ConclusionsIn our setting, in vivo CLE optical biopsy outperforms ex vivo CLE by producing higher quality images and less image deterioration, leading to better diagnostic performance. These results support the in vivo modality as the modality of choice for intraoperative CLE imaging.

Real-time intraoperative surgical telepathology using confocal laser endomicroscopy.

Communication between neurosurgeons and pathologists is mandatory for intraoperative decision-making and optimization of resection, especially for invasive masses. Handheld confocal laser endomicroscopy (CLE) technology provides in vivo intraoperative visualization of tissue histoarchitecture at cellular resolution. The authors evaluated the feasibility of using an innovative surgical telepathology software platform (TSP) to establish real-time, on-the-fly remote communication between the neurosurgeon using CLE and the pathologist. CLE and a TSP were integrated into the surgical workflow for 11 patients with brain masses (6 patients with gliomas, 3 with other primary tumors, 1 with metastasis, and 1 with reactive brain tissue). Neurosurgeons used CLE to generate video-flow images of the operative field that were displayed on monitors in the operating room. The pathologist simultaneously viewed video-flow CLE imaging using a digital tablet and communicated with the surgeon while physically located outside the operating room (1 pathologist was in another state, 4 were at home, and 6 were elsewhere in the hospital). Interpretations of the still CLE images and video-flow CLE imaging were compared with the findings on the corresponding frozen and permanent H&E histology sections. Overall, 24 optical biopsies were acquired with mean ± SD 2 ± 1 optical biopsies per case. The mean duration of CLE system use was 1 ± 0.3 minutes/case and 0.25 ± 0.23 seconds/optical biopsy. The first image with identifiable histopathological features was acquired within 6 ± 0.1 seconds. Frozen sections were processed within 23 ± 2.8 minutes, which was significantly longer than CLE usage (p < 0.001). Video-flow CLE was used to correctly interpret tissue histoarchitecture in 96% of optical biopsies, which was substantially higher than the accuracy of using still CLE images (63%) (p = 0.005). When CLE is employed in tandem with a TSP, neurosurgeons and pathologists can view and interpret CLE images remotely and in real time without the need to biopsy tissue. A TSP allowed neurosurgeons to receive real-time feedback on the optically interrogated tissue microstructure, thereby improving cross-functional communication and intraoperative decision-making and resulting in significant workflow advantages over the use of frozen section analysis.

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.

Progress in Confocal Laser Endomicroscopy for Neurosurgery and Technical Nuances for Brain Tumor Imaging With Fluorescein.

Background: Previous studies showed that confocal laser endomicroscopy (CLE) images of brain tumors acquired by a first-generation (Gen1) CLE system using fluorescein sodium (FNa) contrast yielded a diagnostic accuracy similar to frozen surgical sections and histologic analysis. We investigated performance improvements of a second-generation (Gen2) CLE system designed specifically for neurosurgical use.Methods: Rodent glioma models were used for in vivo and rapid ex vivo CLE imaging. FNa and 5-aminolevulinic acid were used as contrast agents. Gen1 and Gen2 CLE images were compared to distinguish cytoarchitectural features of tumor mass and margin and surrounding and normal brain regions. We assessed imaging parameters (gain, laser power, brightness, scanning speed, imaging depth, and Z-stack [3D image acquisition]) and evaluated optimal values for better neurosurgical imaging performance with Gen2.Results: Efficacy of Gen1 and Gen2 was similar in identifying normal brain tissue, vasculature, and tumor cells in masses or at margins. Gen2 had smaller field of view, but higher image resolution, and sharper, clearer images. Other advantages of the Gen2 were auto-brightness correction, user interface, image metadata handling, and image transfer. CLE imaging with FNa allowed identification of nuclear and cytoplasmic contours in tumor cells. Injection of higher dosages of FNa (20 and 40 mg/kg vs. 0.1–8 mg/kg) resulted in better image clarity and structural identification. When used with 5-aminolevulinic acid, CLE was not able to detect individual glioma cells labeled with protoporphyrin IX, but overall fluorescence intensity was higher (p < 0.01) than in the normal hemisphere. Gen2 Z-stack imaging allowed a unique 3D image volume presentation through the focal depth.Conclusion: Compared with Gen1, advantages of Gen2 CLE included a more responsive and intuitive user interface, collection of metadata with each image, automatic Z-stack imaging, sharper images, and a sterile sheath. Shortcomings of Gen2 were a slightly slower maximal imaging speed and smaller field of view. Optimal Gen2 imaging parameters to visualize brain tumor cytoarchitecture with FNa as a fluorescent contrast were defined to aid further neurosurgical clinical in vivo and rapid ex vivo use. Further validation of the Gen2 CLE for microscopic visualization and diagnosis of brain tumors is ongoing.

Utilization of intraoperative confocal laser endomicroscopy in brain tumor surgery.

Precise identification of tumor margins is of the utmost importance in neuro-oncology. Confocal microscopy is capable of rapid imaging of fresh tissues at cellular resolution and has been miniaturized into handheld probe-based systems suitable for use in the operating room. We aimed to perform a literature review to provide an update on the current status of confocal laser endomicroscopy (CLE) technology for brain tumor surgery. Aside from benchtop confocal microscopes used in ex vivo fashion, there are four CLE systems that have been investigated for potential application in the workflow of brain tumor surgery. Preclinical studies on animal tumor models and clinical studies on human brain tumors have assessed in vivo and ex vivo imaging approaches, suggesting that confocal microscopy holds promise for rapid identification of the characteristic (diagnostic) histological features of tumor and normal brain tissues. However, there are few studies assessing diagnostic accuracy sufficient to provide a definitive determination of the clinical and economical value of CLE in brain tumor surgery. Intraoperative real-time, high-resolution tissue imaging has significant clinical potential in the field of neuro-oncology. CLE is an emerging imaging technology that shows promise for improving brain tumor surgery workflow in in vivo and ex vivo studies. Future clinical studies are necessary to demonstrate clinical and economic benefit of CLE.

Online Robust Endomicroscopy Video Mosaicking Using Robot Prior

This letter discusses the development of a mosaicking algorithm for building large- and high-resolution confocal images. Due to the nature of optics and vision systems in general, there is still a dilemma between choosing a wide field-of-view and high resolution. The most accepted solution is to opt for a high-resolution optics and expand the FOV algorithmically thanks to mosaicking approaches. The study reported in this letter consists of online and real-time construction of large mosaics using individual confocal images with a micrometer resolution. These individual images are provided by a confocal laser endomicroscopy system which can grab in vivo real-time images through a minimally invasive access. The acquisition of the confocal images is achieved by moving the imaging probe on the studied sample surface with a constant contact between the probe and the sample. The mosaicking algorithm proposed in this letter deals with the combination of both the robot inputs and the image registrations. The proposed method has demonstrated very promising performances in terms of accuracy and robustness with regard to image noise (poor image quality or loss of contact between the probe and the sample) as well as misregistration issues. Experiments carried out with a highly accurate robotic system and a ground truth obtained by conventional optical microscopy demonstrate the robustness of the proposed approach.

Prospective evaluation of the utility of intraoperative confocal laser endomicroscopy in patients with brain neoplasms using fluorescein sodium: experience with 74 cases.

This study evaluated the utility, specificity, and sensitivity of intraoperative confocal laser endomicroscopy (CLE) to provide diagnostic information during resection of human brain tumors. CLE imaging was used in the resection of intracranial neoplasms in 74 consecutive patients (31 male; mean age 47.5 years; sequential 10-month study period). Intraoperative in vivo and ex vivo CLE was performed after intravenous injection of fluorescein sodium (FNa). Tissue samples from CLE imaging-matched areas were acquired for comparison with routine histological analysis (frozen and permanent sections). CLE images were classified as diagnostic or nondiagnostic. The specificities and sensitivities of CLE and frozen sections for gliomas and meningiomas were calculated using permanent histological sections as the standard. CLE images were obtained for each patient. The mean duration of intraoperative CLE system use was 15.7 minutes (range 3-73 minutes). A total of 20,734 CLE images were correlated with 267 biopsy specimens (mean number of images/biopsy location, in vivo 84, ex vivo 70). CLE images were diagnostic for 45.98% in vivo and 52.97% ex vivo specimens. After initiation of CLE, an average of 14 in vivo images and 7 ex vivo images were acquired before identification of a first diagnostic image. CLE specificity and sensitivity were, respectively, 94% and 91% for gliomas and 93% and 97% for meningiomas. CLE with FNa provided intraoperative histological information during brain tumor removal. Specificities and sensitivities of CLE for gliomas and meningiomas were comparable to those for frozen sections. These data suggest that CLE could allow the interactive identification of tumor areas, substantially improving intraoperative decisions during the resection of brain tumors.

Handheld confocal laser endomicroscopic imaging utilizing tumor-specific fluorescent labeling to identify experimental glioma cells in vivo.

Background:We have reported that handheld confocal laser endomicroscopy (CLE) can be used with various nonspecific fluorescent dyes to improve the microscopic identification of brain tumor and its boundaries. Here, we show that CLE can be used experimentally with tumor-specific fluorescent labeling to define glioma margins in vivo.Methods:Thirteen rats underwent craniectomy and in vivo imaging 21 days after implantation with green fluorescent protein (GFP)-labeled U251 (n = 7) cells or epidermal growth factor receptor (EGFR) overexpressing F98 cells (n = 6). Fluorescein isothiocyanate (FITC) conjugated EGFR fluorescent antibody (FITC-EGFR) was applied for contrast in F98 tumors. Confocal images of normal brain, obvious tumor, and peritumoral zones were collected using the CLE system. Bench-top confocal microscopy and hematoxylin and eosin-stained sections were correlated with CLE images.Results:GFP and FITC-EGFR fluorescence of glioma cells were detected by in vivo visible-wavelength fluorescence CLE. CLE of GFP-labeled tumors revealed bright individual satellite tumor cells within peritumoral tissue, a definitive tumor border, and subcellular structures. Imaging with FITC-EGFR labeling provided weaker contrast in F98-EGFR tumors but was able to delineate tumor cells. Imaging with both methods in various tumor regions correlated with standard confocal imaging and clinical histology.Conclusions:These data suggest that in vivo CLE of selectively tagged neoplasms could allow specific interactive identification of tumoral areas. Imaging of GFP and FITC-EGFR provides real-time histologic information precisely related to the site of microscopic imaging of tumor.

Confocal Laser Endomicroscopy – The Potential Role of In Vivo Characterization of Neoplasia in the Gastrointestinal Tract

Confocal laser endomicroscopy (CLE) is a novel microscope which enables real-time imaging with detailed mucosal and sub mucosal architectures throughout the gastrointestinal tract. New optical technology using the principle of light reflection, scattering and refocusing dramatically increases image resolution thus has the potential of real time optical biopsy. Two types of CLE system are commercially available; endoscope-based type (eCLE) which integrated CLE in the tip of scope and probe-based type (pCLE) which uses a probe through the accessory channel of a traditional endoscope. Clinical data applying CLE for the detection of neoplastic lesions in the gastrointestinal tract have been increasingly reported including esophagus, stomach and colon. The probe based system has a probe that can be used in the bile ducts to evaluate biliary strictures. More recently, a needle based CLE which passes through a fine-needle aspiration needle has been introduced into pancreatic cystic lesions. CLE has demonstrated promising in vivo data in various clinical arenas. Further validation regarding reproducible image classification, inter and intra observer variability, learning curve, and cost effectiveness remain to be demonstrated.

Probe-based Confocal Laser Endomicroscopy of the Urinary Tract: The Technique

Probe-based confocal laser endomicroscopy (CLE) is an emerging optical imaging technology that enables real-time in vivo microscopy of mucosal surfaces during standard endoscopy. With applications currently in the respiratory and gastrointestinal tracts, CLE has also been explored in the urinary tract for bladder cancer diagnosis. Cellular morphology and tissue microarchitecture can be resolved with micron scale resolution in real time, in addition to dynamic imaging of the normal and pathological vasculature. The probe-based CLE system (Cellvizio, Mauna Kea Technologies, France) consists of a reusable fiberoptic imaging probe coupled to a 488 nm laser scanning unit. The imaging probe is inserted in the working channels of standard flexible and rigid endoscopes. An endoscope-based CLE system (Optiscan, Australia), in which the confocal endomicroscopy functionality is integrated onto the endoscope, is also used in the gastrointestinal tract. Given the larger scope diameter, however, application in the urinary tract is currently limited to ex vivo use. Confocal image acquisition is done through direct contact of the imaging probe with the target tissue and recorded as video sequences. As in the gastrointestinal tract, endomicroscopy of the urinary tract requires an exogenenous contrast agent-most commonly fluorescein, which can be administered intravenously or intravesically. Intravesical administration is a well-established method to introduce pharmacological agents locally with minimal systemic toxicity that is unique to the urinary tract. Fluorescein rapidly stains the extracellular matrix and has an established safety profile. Imaging probes of various diameters enable compatibility with different caliber endoscopes. To date, 1.4 and 2.6 mm probes have been evaluated with flexible and rigid cystoscopy. Recent availability of a < 1 mm imaging probe opens up the possibility of CLE in the upper urinary tract during ureteroscopy. Fluorescence cystoscopy (i.e. photodynamic diagnosis) and narrow band imaging are additional endoscope-based optical imaging modalities that can be combined with CLE to achieve multimodal imaging of the urinary tract. In the future, CLE may be coupled with molecular contrast agents such as fluorescently labeled peptides and antibodies for endoscopic imaging of disease processes with molecular specificity.

Diagnostic performance of two confocal endomicroscopy systems in detecting Barrett's dysplasia: a pilot study using a novel bioprobe in ex vivo tissue

There are currently 2 existing confocal laser endomicroscopy (CLE) platforms: probe-based CLE (pCLE) and endoscope-based CLE (eCLE) systems, each with its own criteria for identifying dysplasia in Barrett's esophagus (BE). The diagnostic performance of these 2 systems has not been directly compared. Preclinical, feasibility study. We compared the interrater agreement and diagnostic performance of the pCLE and eCLE systems. In addition, we evaluated a new BE endomicroscopy criteria based on fluorescent glucose intensity uptake. Thirteen patients with Barrett's esophagus and high-grade dysplasia or early cancer undergoing 16 EMR. CLE imaging was performed using two different probes with 2-[N-(7-nitrobenz-2-oxa-1,3-diaxol-4-yl)amino]-2-deoxyglucose, a fluorescent glucose analog with preferential uptake in dysplastic mucosa to supply contrast. Four quadrants were imaged per specimen with a total of 64 imaged mucosal sites presented to three gastroenterologists. Interobserver agreement and accuracy for dysplasia was assessed of images classified according to Miami criteria, stacked eCLE images classified using the Mainz criteria and a novel fluorescence intensity criteria. The interrater agreements were 0.17, 0.68, and 0.87 for the Miami, Mainz, and the fluorescence intensity criteria, respectively. Overall accuracy in detecting dysplasia was 37% (95% CI, 30.3-43.9), 44.3% (95% CI, 37.3-50.9), and 78.6% (95% CI, 72.2-83.3) for the Miami, Mainz, and the fluorescence intensity criteria, respectively. This imaging technique and proposed fluorescence intensity criteria using 2-[N-(7-nitrobenz-2-oxa-1,3-diaxol-4-yl)amino]-2-deoxyglucose in EMR tissue will require in vivo validation and cannot be directly used with the current eCLE and pCLE clinical applications. In this preclinical feasibility study, the use of an eCLE system with a topical fluorescent contrast in ex vivo EMR tissue demonstrated higher interrater agreement and accuracy.

Colorectal cancer screening in patients with ulcerative and crohnʼs colitis with use of colonoscopy, chromoendoscopy and confocal endomicroscopy

Patients with ulcerative colitis and Crohn's colitis have increased risk of colorectal cancer. Current screening endoscopy protocols based on white light endoscopy (WLE) and random biopsies are laborious and of uncertain sensitivity. Novel endoscopic techniques include chromoendoscopy (CE) and confocal laser endomicroscopy (CLE). The aim was to compare WLE and CE for the detection of intraepithelial neoplasia (IEN). Furthermore, we analysed the sensitivity and specificity of CE and CLE for the diagnosis of IEN. The cohort consisted of 30 patients examined by WLE, CE with 0.4% indigocarmine, and by a CLE system Pentax EC-3870CIFK during one examination. Additional 15 patients were examined by conventional protocol only. Random biopsies and biopsies from all suspicious lesions were taken. We compared the number of IENs detected by WLE and CE and analysed the predictive values of CE and CLE for the histology diagnosis. There were 1584 random biopsies (35.2 per patient) taken. There were 78 targeted biopsies (1.7 per patient) taken in 24 of 45 patients examined by WLE and an additional 36 biopsies in 16 of 30 patients examined by CE (1.17 additional per patient). There were no IENs found on random biopsies versus six low-grade or high-grade IENs in four patients (two detected by WLE, four additional by CE) from targeted biopsies, P=0.02. A total of 100 suspicious lesions were detected and analysed by CE and histology. CLE could not examine 32 of 100 lesions (two of 30 flat vs. 30 of 70 pedunculated lesions, P=0.0002, odds ratio 10.5). The sensitivity of CE/CLE for low-grade or high-grade IEN was 100/100%, the specificity 96.8/98.4%, positive predictive value was 62.5/66.7% and negative predictive value was 100/100%. Targeted biopsies are superior to random biopsies in the screening of IEN in patients with inflammatory bowel disease. CE increases the diagnostic yield of WLE. In our study CLE did not provide additional clinical benefits.

Endomicroscopy in the evaluation of Barrettʼs esophagus

Confocal laser endomicroscopy (CLE) can provide real-time, microscopic visualization of the gastrointestinal mucosa, allowing an endoscopic approach to the histologic evaluation of Barrett's esophagus and Barrett's esophagus-associated neoplasia. Both endoscope-based (eCLE) and probe-based (pCLE) CLE systems have been used to evaluate Barrett's esophagus and Barrett's esophagus-associated neoplasia. Criteria for distinguishing Barrett's esophagus with neoplasia from nondysplastic Barrett's esophagus have been developed and validated for both eCLE and pCLE. Several studies have shown excellent detection of Barrett's esophagus neoplasia by CLE, and the technique may be used to guide endoscopic therapy. Advanced endomicroscopy systems and peptides and antibodies that target neoplasia are in development. CLE has provided a new way of evaluating Barrett's esophagus and Barrett's esophagus-associated neoplasia and is being used to improve detection and management of neoplasia in Barrett's esophagus.

Confocal Laser Endomicroscopy: Technical Advances and Clinical Applications

Since its introduction in 2004, confocal laser endomicroscopy (CLE) has emerged as a valuable tool for gastrointestinal endoscopic imaging. Endomicroscopy enables the endoscopist to obtain real time in vivo histology during ongoing endoscopy thereby creating “optical biopsies.” To date, numerous studies have shown potential applications of endomicroscopy in the clinical setting, including in vivo diagnosis of esophageal squamous cell carcinoma, Barrett’s esophagus, celiac disease, and colonic polyps. Moreover, recent data suggest the potential application of endomicroscopy in the field of molecular imaging. Additionally, in recent months new applications and developments in the field of confocal imaging were introduced including endomicroscopy of the liver, pancreatic, and bile ducts. Furthermore, by introducing a new needle-based confocal imaging system, which is small enough to be introduced through a 22gauge puncture needle, a wide field for new applications of endomicroscopic imaging has been opened. Currently, 2 CE- and US Food and Drug Administration (FDA)approved devices for endomicroscopy are available (Figures 1 and 2; Supplementary Table 1). In this review, we introduce both systems and discuss new technical advances and clinical applications of CLE.

S1579: Role of Probe-Based Confocal Laser Endomicroscopy (pCLE) in Detection of Dysplasia in Duodenal Polyps

Confocal laser endomicroscopy (CLE) is rapidly emerging as a highly accurate method for in vivo imaging of gastrointestinal tract pathology. Probe based CLE (pCLE) systems are now available (Mauna Kea Technologies, Paris) which may be more convenient and versatile since they can be used as needed with any endoscopy system. Recent data from our group and others suggests pCLE can accurately detect dysplasia in the colon and Barrett's esophagus. Duodenal polyps present unique challenges since they are typically flat, and endoscopic mucosal resection (EMR) is associated with increased risk, particularly ampullary adenomas. Furthermore, biopsy to confirm adenomatous tissue may make subsequent EMR more difficult by “tacking down” the mucosa and risk pancreatitis in the ampullary adenomas. We hypothesized the pCLE could be used as an alternative to biopsy and allow the endoscopist to proceed directly to EMR of duodenal adenomatous polyps. We evaluated the sensitivity, specificity and accuracy of probe-based pCLE in patients with duodenal polyps with associated dysplasia.

The Role of Probe-Based Confocal Laser Endomicroscopy (pCLE) in Detection of Dysplasia in Duodenal Polyps

Background: Confocal laser endomicroscopy (CLE) is rapidly emerging as a highly accurate method for in vivo imaging of gastrointestinal tract pathology. Probe based CLE (pCLE) systems are now available (Mauna Kea Technologies, Paris) which may be more convenient and versatile since they can be used as needed with any endoscopy system. Recent data from our group and others suggests pCLE can accurately detect dysplasia in the colon and Barrett's esophagus. Duodenal polyps present unique challenges since they are typically flat, and endoscopic mucosal resection (EMR) is associated with increased risk (Bacani and Wallace, Surgical Endoscopy, 2008). Furthermore, biopsy to confirm adenomatous tissue may make subsequent EMR more difficult by “tacking down” the mucosa. We hypothesized the pCLE could be used as an alternative to biopsy and allow the endoscopist to proceed directly to EMR of duodenal adenomatous polyps. We evaluated the sensitivity, specificity and accuracy of probe-based pCLE in patients with duodenal polyps with associated dysplasia. Methods: Two experts (MW and AB) who had already performed more than 100 pCLE exams collected standardized pCLE video sequences and matched biopsies in 12 patients with duodenal polyps. Histological confirmation of dysplasia by an expert GI pathologist was used as the gold standard. The 12 cases were randomized and viewed offline by the two experts who were unaware of actual histopathology results. The features of dysplasia include abnormalities of vascular, cellular and nuclear patterns similar to those reported in Barrett's esophagus (Pohl et al. Gut, 2008). The sensitivity, specificity, accuracy, positive and negative predictive values were calculated. Results: Five cases had high grade dysplasia and seven had nondysplastic duodenal polyp by histopathology. The overall accuracy for the diagnosis of dysplasia with pCLE by the two experts was 83%, sensitivity was 90%, and specificity was 78.5% with positive and negative predictive values being 75.5% and 93% respectively. Conclusion: This preliminary study suggests that confocal endomicroscopy may be helpful in detection of dysplasia in duodenal polyps and directing its removal at the time of endoscopy.

Confocal endomicroscopy for in vivo detection of microvascular architecture in normal and malignant lesions of upper gastrointestinal tract

Confocal laser endomicroscopy allows subsurface analysis of gastrointestinal mucosa during ongoing endoscopy. The present study assessed the feasibility of in vivo detecting superficial vascular architecture by confocal endomicroscopy in normal upper gastrointestinal mucosa and malignant lesions. Early gastric cancer in eight patients, superficial esophageal carcinoma in six patients, and asymptomatic normal control in 10 patients were studied by confocal endomicroscopy. The characteristic of endomicroscopic microvascular architecture from normal and malignant mucosa was described and images were evaluated. Confocal endomicroscopy enabled clear visualization of the vascular networks of gastroesophageal mucosa. Honeycomb-like and coil-shaped regular microvascular architecture surrounding gastric pits were visible in the normal gastric body and antrum, respectively. Differentiated gastric cancerous mucosa showed hypervascularity and various caliber microvessels with irregular shapes. Undifferentiated gastric cancers disclosed a hypovascularity and irregular short branch vessels. Normal squamous epithelium had regular intraepithelial papillary capillary loops (IPCLs) directed toward the luminal surface. In superficial esophageal squamous carcinoma, dilated IPCLs were visible at the upper layer of the squamous mucosa. In esophageal adenocarcinoma, abnormal microvascular architecture showed tortuous and various calibers blood vessels. Of all the images, 41% were graded as good quality. The mean kappa value for interobserver agreement for the prediction of cancerous mucosa was 0.792. Confocal laser endomicroscopy system could yield very clear images of superficial microvascular network in the gastroesophageal mucosal layer both in malignant and normal mucosa. Endomicroscopic observation of vascular architecture may be of assistance in the identification of early gastroesophageal cancers.