Endoscopic ultrasound guided needle-based confocal laser endomicroscopy in solid pancreatic masses - a prospective validation study

The role of needle-based confocal laser endomicroscopy in the diagnosis of pancreatic neuroendocrine tumors

BACKGROUND/AIMS

Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) is a highly accurate method for diagnosing pancreatic neuroendocrine tumors (PNETs); however, some PNETs are difficult to diagnose. Recently, the efficacy of needle-based confocal laser endomicroscopy (nCLE) in diagnosing solid pancreatic masses has been reported. However, the efficacy of nCLE in the diagnosis of PNETs remains unknown and only a small number of cases have been reported. Hence, this study aimed to evaluate the efficacy of nCLE in the diagnosis of PNETs.

METHODS

This single-center retrospective study evaluated 30 consecutive patients with suspected PNETs on contrast-enhanced computed tomography, who consented to nCLE combined with EUS-FNA and were diagnosed using EUS-FNA or surgical resection. The diagnostic criteria for PNETs using nCLE were based on the nesting and trabecular and glandular arrangement of tumor cell clusters surrounded by capillary vessels and fibrosis, as reported in previous studies.

RESULTS

The diagnosis using nCLE was classified into three categories: misdiagnosis in three cases (10%), non-diagnostic in six cases (20%), and diagnostic in 21 cases (70%). nCLE was able to diagnose PNET in one of the two cases with inconclusive EUS-FNA.

CONCLUSIONS

Although further development of the resolution and optimization of the diagnostic criteria are required, nCLE may constitute a useful diagnostic option in cases of inconclusive EUS-FNA for PNETs.

The development and clinical application of microscopic endoscopy for in vivo optical biopsies: Endocytoscopy and confocal laser endomicroscopy

Endoscopies are crucial for detecting and diagnosing diseases in gastroenterology, pulmonology, urology, and other fields. To accurately diagnose diseases, sample biopsies are indispensable and are currently considered the gold standard. However, random 4-quadrant biopsies have sampling errors and time delays. To provide intraoperative real-time microscopic images of suspicious lesions, microscopic endoscopy for in vivo optical biopsy has been developed, including endocytoscopy and confocal laser endomicroscopy. This article reviews recent advances in technology and clinical applications, as well as their shortcomings and future directions.

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.

Morphometric Assessment of Confocal Laser Endomicroscopy for Pancreatic Ductal Adenocarcinoma, an Ex-Vivo Pilot Study

Ex-vivo freshly surgical removed pancreatic ductal adenocarcinoma (PDAC) specimens were assessed using pCLE and then processed for paraffin embeding and histopathological diagnostic in an endeavour to find putative image analysis algorithms that might recognise adenocarcinoma. Methods: Twelve patients diagnosed with PDAC on endoscopic ultrasound and FNA confirmation underwent surgery. Removed samples were sprayed with acriflavine as contrast agent, underwent pCLE with an experimental probe and compared with previous recordings of normal pancreatic tissue. Subsequently, all samples were subjected to cross-sectional histopathology, including surgical resection margins for controls. pCLE records, as well as corespondant cytokeratin-targeted immunohistochemistry images were processed using the same morphological classifiers in the Image ProPlus AMS image analysis software. Specific morphometric classifiers were automatically generated on all images: Area, Hole Area (HA), Perimeter, Roundness, Integrated Optical Density (IOD), Fractal Dimension (FD), Ferret max (Fmax), Ferret mean (Fmean), Heterogeneity and Clumpiness. Results: After histopathological confirmation of adenocarcinoma areas, we have found that the same morphological classifiers could clearly differentiate between tumor and non-tumor areas on both pathology and correspondand pCLE (area, roundness, IOD, ferret and heterogeneity (p < 0.001), perimeter and hole area (p < 0.05). Conclusions: This pilot study proves that classical morphometrical classifiers can clearly differentiate adenocarcimoma on pCLE data, and the implementation in a live image-analysis algorithm might help in improving the specificity of pCLE in vivo diagnostic.

Current Status of Needles in the Optimization of Endoscopic Ultrasound-Guided Procedures

Endoscopic ultrasound (EUS) is among the most important tools for the evaluation of gastrointestinal tumors and affected areas around the gastrointestinal tract. It enables the acquisition of material from abnormal lesions via the gastrointestinal wall for tissue confirmation via endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA). EUS-FNA has played a vital role in oncological care and has become the standard method for tissue sampling. The choice of needle type is an important factor determining tissue acquisition and has been evaluated by many researchers. New needles are introduced into the market almost every year, and opinions vary regarding proper needle selection. While there are diverse opinions but no definitive recommendations about the use of one particular device, fine-needle biopsy needles may provide detailed information on a tissue’s architecture based on greater sample yields. This permits additional analyses, including genetic sequencing and phenotyping, thereby enabling the provision of more personalized treatment plans. Furthermore, other EUS-guided procedures have been developed, including interventional EUS and through-the-needle devices. Given the continued attempts to improve the diagnostic ability and therapeutic techniques, we review in detail the available types of puncture needles to provide guidance on the selection of the appropriate needle types.

SAGES TAVAC safety and efficacy analysis confocal laser endomicroscopy

BACKGROUND

Confocal laser endomicroscopy (CLE) is a novel endoscopic adjunct that allows real-time in vivo histological examination of mucosal surfaces. By using intravenous or topical fluorescent agents, CLE highlights certain mucosal elements that facilitate an optical biopsy in real time. CLE technology has been used in different organ systems including the gastrointestinal tract. There has been numerous studies evaluating this technology in gastrointestinal endoscopy, our aim was to evaluate the safety, value, and efficacy of this technology in the gastrointestinal tract.

METHODS

The Society of American Gastrointestinal and Endoscopic Surgeons (SAGES) Technology and Value Assessment Committee (TAVAC) performed a PubMed/Medline database search of clinical studies involving CLE in May of 2018. The literature search used combinations of the keywords: confocal laser endomicroscopy, pCLE, Cellvizio, in vivo microscopy, optical histology, advanced endoscopic imaging, and optical diagnosis. Bibliographies of key references were searched for relevant studies not covered by the PubMed search. Case reports and small case series were excluded. The manufacturer's website was also used to identify key references. The United States Food and Drug Administration (U.S. FDA) Manufacturer And User facility and Device Experience (MAUDE) database was searched for reports regarding the device malfunction or injuries.

RESULTS

The technology offers an excellent safety profile with rare adverse events related to the use of fluorescent agents. It has been shown to increase the detection of dysplastic Barrett's esophagus, gastric intraepithelial neoplasia/early gastric cancer, and dysplasia associated with inflammatory bowel disease when compared to standard screening protocols. It also aids in the differentiation and classification of colorectal polyps, indeterminate biliary strictures, and pancreatic cystic lesions.

CONCLUSIONS

CLE has an excellent safety profile. CLE can increase the diagnostic accuracy in a number of gastrointestinal pathologies.

Management of Incidental Pancreatic Cystic Lesions: Integrating Novel Diagnostic and Prognostic Factors With Current Clinical Guidelines

Owing to increased detection rates, the diagnosis and management of incidental pancreatic cysts has become a common predicament. Up to 13% of patients undergoing cross-sectional imaging studies for other indications are found to have pancreatic cystic lesions. Although most cystic lesions are benign, the malignant potential of several types of pancreatic cysts makes accurate classification vital to directing therapy. To this end, advances in the last decade led to better characterization of pancreatic cyst morphology and hence enhanced the ability to predict underlying histopathology, and biological behavior. Although accurate classification remains a challenge, the utilization of complementary diagnostic tools is the optimal approach to dictate management. The following review includes a description of pancreatic cysts, a critical review of current and emerging diagnostic techniques and a review of recent guidelines in the management of incidental pancreatic cysts.

Endoscopic ultrasound-guided tissue sampling of pancreatic lesions

Important advancements in endoscopic ultrasound-guided tissue sampling techniques and development of new needle designs have improved the diagnostic yield of pancreatic lesions. This innovation in endoscopic ultrasound has also opened the door for early diagnosis and precision therapy in the management of cancer patients. Endoscopic ultrasound fine needle biopsy is an invaluable tool and newer biopsy designs will probably play a pivotal role in the management of pancreatic lesions in the next future. Aim of the current review was to provide an overview on the available techniques and devices for the endoscopic ultrasound-guided sampling of pancreatic solid and cystic lesions.

Current Status of Endoscopic Ultrasound Techniques for Pancreatic Neoplasms

Endoscopic ultrasound (EUS) now plays an important role in the management of pancreatic neoplasms. There are various types of pancreatic neoplasms, from benign to malignant lesions, and the role of EUS ranges from the imaging diagnosis to treatment. EUS is useful for the detection, characterization, and tissue acquisition of pancreatic lesions. Recent advancement of contrast-enhanced harmonic EUS and elastography enables better characterization of pancreatic lesions. In addition to these enhanced EUS imaging techniques, EUS-guided tissue acquisition is now the standard procedure to establish the pathological diagnosis of pancreatic neoplasms. While these diagnostic roles of EUS have been established, EUS-guided interventions such as ablation and drainage are also increasingly utilized in the management of pancreatic neoplasms. However, most of these EUS-guided interventions are not yet standardized in terms of techniques and devices and thus need further investigations.

Recent advancement in EUS-guided fine needle sampling

EUS-guided tissue acquisition technique plays an essential role for evaluation of gastrointestinal tumors. Several components affect the yield of EUS-guided tissue acquisition outcomes such as sampling techniques, use of ROSE (rapid onsite evaluation), training and experience, and needle designs. In this review we discuss advancement in EUS-guided fine needle sampling.

Advanced EUS Guided Tissue Acquisition Methods for Pancreatic Cancer

Pancreas cancer is a lethal cancer as the majority patients are diagnosed at an advanced incurable stage. Despite improvements in diagnostic modalities and management strategies, including surgery and chemotherapies, the outcome of pancreas cancer remains poor. Endoscopic ultrasound (EUS) is an important imaging tool for pancreas cancer. For decades, resected pancreas cancer and other cancer specimens have been used to identify tissue biomarkers or genomics for precision therapy; however, only 20% of patients undergo surgery, and thus, this framework is not useful for unresectable pancreas cancer. With advancements in needle technologies, tumor specimens can be obtained at the time of tissue diagnosis. Tumor tissue can be used for development of personalized cancer treatment, such as performing whole exome sequencing and global genomic profiling of pancreas cancer, development of tissue biomarkers, and targeted mutational assays for precise chemotherapy treatment. In this review, we discuss the recent advances in tissue acquisition of pancreas cancer.