EUS-guided confocal laser endomicroscopy: prediction of dysplasia in intraductal papillary mucinous neoplasms (with video)

Endoscopic ultrasound-guided needle-based confocal laser endomicroscopy for pancreatic cystic lesions: current status and future prospects

Pancreatic cystic lesions (PCLs) have increased in prevalence due to the increased usage and advancements in cross-sectional abdominal imaging. Current diagnostic techniques cannot distinguish between PCLs requiring surgery, close surveillance, or expectant management. This has increased the morbidity and healthcare costs from inappropriately aggressive and conservative management strategies. Endoscopic ultrasound (EUS) needle-based confocal laser endomicroscopy (nCLE) allows for microscopic examination and delineation of the surface epithelium of PCLs. Landmark studies have identified characteristics distinguishing various types of PCLs, confirmed the high diagnostic yield of EUS-nCLE (especially for PCLs with an equivocal diagnosis), and shown that EUS-nCLE helps to change management and reduce healthcare costs. Refining procedure technique and reducing procedure length have improved the safety of EUS-nCLE. The utilization of artificial intelligence and its combination with other EUS-based advanced diagnostic techniques would further improve the results of EUS-based PCL diagnosis. A structured training program and device improvements to allow more complete mapping of the pancreas cyst epithelium will be crucial for the widespread adoption of this promising technology.

The application of artificial intelligence in EUS

Artificial intelligence (AI) is an epoch-making technology, among which the 2 most advanced parts are machine learning and deep learning algorithms that have been further developed by machine learning, and it has been partially applied to assist EUS diagnosis. AI-assisted EUS diagnosis has been reported to have great value in the diagnosis of pancreatic tumors and chronic pancreatitis, gastrointestinal stromal tumors, esophageal early cancer, biliary tract, and liver lesions. The application of AI in EUS diagnosis still has some urgent problems to be solved. First, the development of sensitive AI diagnostic tools requires a large amount of high-quality training data. Second, there is overfitting and bias in the current AI algorithms, leading to poor diagnostic reliability. Third, the value of AI still needs to be determined in prospective studies. Fourth, the ethical risks of AI need to be considered and avoided.

Structured training program on confocal laser endomicroscopy for pancreatic cystic lesions: a multicenter prospective study among early-career endosonographers (with video)

BACKGROUND AND AIMS

Data on how to teach endosonographers needle-based confocal laser endomicroscopy (nCLE)-guided histologic diagnosis of pancreatic cystic lesions (PCLs) are limited. Hence, we developed and tested a structured educational program to train early-career endosonographers in nCLE-guided diagnosis of PCLs.

METHODS

Twenty-one early-career nCLE-naïve endosonographers watched a teaching module outlining nCLE criteria for diagnosing PCLs. Participants then reviewed 80 high-yield nCLE videos, recorded diagnoses, and received expert feedback (phase 1). Observers were then randomized to a refresher feedback session or self-learning at 4 weeks. Eight weeks after training, participants independently assessed the same 80 nCLE videos without feedback and provided histologic predictions (phase 2). Diagnostic performance of nCLE to differentiate mucinous versus nonmucinous PCLs and to diagnose specific subtypes were analyzed using histopathology as the criterion standard. Learning curves were determined using cumulative sum analysis.

RESULTS

Accuracy and diagnostic confidence for differentiating mucinous versus nonmucinous PCLs improved as endosonographers progressed through nCLE videos in phase 1 (P < .001). Similar trends were observed with the diagnosis of PCL subtypes. Most participants achieved competency interpreting nCLE, requiring a median of 38 assessments (range, 9-67). During phase 2, participants independently differentiated PCLs with high accuracy (89%), high confidence (83%), and substantial interobserver agreement (κ = .63). Accuracy for nCLE-guided PCL subtype diagnoses ranged from 82% to 96%. The learned nCLE skills did not deteriorate at 8 weeks and were not impacted by a refresher session.

CONCLUSIONS

We developed a practical, effective, and durable educational intervention to train early-career endosonographers in nCLE-guided diagnosis of PCLs.

Improving Pancreatic Cyst Management: Artificial Intelligence-Powered Prediction of Advanced Neoplasms through Endoscopic Ultrasound-Guided Confocal Endomicroscopy

Despite the increasing rate of detection of incidental pancreatic cystic lesions (PCLs), current standard-of-care methods for their diagnosis and risk stratification remain inadequate. Intraductal papillary mucinous neoplasms (IPMNs) are the most prevalent PCLs. The existing modalities, including endoscopic ultrasound and cyst fluid analysis, only achieve accuracy rates of 65-75% in identifying carcinoma or high-grade dysplasia in IPMNs. Furthermore, surgical resection of PCLs reveals that up to half exhibit only low-grade dysplastic changes or benign neoplasms. To reduce unnecessary and high-risk pancreatic surgeries, more precise diagnostic techniques are necessary. A promising approach involves integrating existing data, such as clinical features, cyst morphology, and data from cyst fluid analysis, with confocal endomicroscopy and radiomics to enhance the prediction of advanced neoplasms in PCLs. Artificial intelligence and machine learning modalities can play a crucial role in achieving this goal. In this review, we explore current and future techniques to leverage these advanced technologies to improve diagnostic accuracy in the context of PCLs.

Intraductal Papillary Mucinous Neoplasm of the Pancreas: A Challenging Diagnosis

Intraductal papillary mucinous neoplasm of the pancreas (IPMN) was classified as a distinct entity from mucinous cystic neoplasm by the WHO in 1995. It represents a mucin-producing tumor that originates from the ductal epithelium and can evolve from slight dysplasia to invasive carcinoma. In addition, different aspects of tumor progression may be seen in the same lesion. Three types are recognized, the branch duct variant, the main duct variant, which shows a much higher prevalence for malignancy, and the mixed-type variant, which combines branch and main duct characteristics. Advances in cross-sectional imaging have led to an increased rate of IPMN detection. The main imaging characteristic of IPMN is the dilatation of the pancreatic duct without the presence of an obstructing lesion. The diagnosis of a branch duct IPMN is based on the proof of its communication with the main pancreatic duct on MRI-MRCP examination. Early identification by imaging of the so-called worrisome features or predictors for malignancy is an important and challenging task. In this review, we will present recent imaging advances in the diagnosis and characterization of different types of IPMNs, as well as imaging tools available for early recognition of worrisome features for malignancy. A critical appraisal of current IPMN management guidelines from both a radiologist's and surgeon's perspective will be made. Special mention is made of complications that might arise during the course of IPMNs as well as concomitant pancreatic neoplasms including pancreatic adenocarcinoma and pancreatic endocrine neoplasms. Finally, recent research on prognostic and predictive biomarkers including radiomics will be discussed.

Recent Developments in the Field of Endoscopic Ultrasound for Diagnosis, Staging, and Treatment of Pancreatic Lesions

Endoscopic ultrasound (EUS) plays a crucial role in the diagnosis of both solid and cystic pancreatic lesions and in the staging of patients with pancreatic cancer through its use for tissue and fluid sampling. Additionally, in cases of precancerous lesions, EUS-guided therapy can also be provided. This review aims to describe the most recent developments regarding the role of EUS in the diagnosis and staging of pancreatic lesions. Moreover, complementary EUS imaging modalities, the role of artificial intelligence, new devices, and modalities for tissue acquisition, and techniques for EUS-guided treatment are discussed.

Deep-Learning-Enabled Computer-Aided Diagnosis in the Classification of Pancreatic Cystic Lesions on Confocal Laser Endomicroscopy

Accurate classification of pancreatic cystic lesions (PCLs) is important to facilitate proper treatment and to improve patient outcomes. We utilized the convolutional neural network (CNN) of VGG19 to develop a computer-aided diagnosis (CAD) system in the classification of subtypes of PCLs in endoscopic ultrasound-guided needle-based confocal laser endomicroscopy (nCLE). From a retrospectively collected 22,424 nCLE video frames (50 videos) as the training/validation set and 11,047 nCLE video frames (18 videos) as the test set, we developed and compared the diagnostic performance of three CNNs with distinct methods of designating the region of interest. The diagnostic accuracy for subtypes of PCLs by CNNs with manual, maximal rectangular, and U-Net algorithm-designated ROIs was 100%, 38.9%, and 66.7% on a per-video basis and 88.99%, 73.94%, and 76.12% on a per-frame basis, respectively. Our per-frame analysis suggested differential levels of diagnostic accuracy among the five subtypes of PCLs, where non-mucinous PCLs (serous cystic neoplasm: 93.11%, cystic neuroendocrine tumor: 84.31%, and pseudocyst: 98%) had higher diagnostic accuracy than mucinous PCLs (intraductal papillary mucinous neoplasm: 84.43% and mucinous cystic neoplasm: 86.1%). Our CNN demonstrated superior specificity compared to the state-of-the-art for the classification of mucinous PCLs (IPMN and MCN), with high specificity (94.3% and 92.8%, respectively) but low sensitivity (46% and 45.2%, respectively). This suggests the complimentary role of CNN-enabled CAD systems, especially for clinically suspected mucinous PCLs.

The Role of Genetic, Metabolic, Inflammatory, and Immunologic Mediators in the Progression of Intraductal Papillary Mucinous Neoplasms to Pancreatic Adenocarcinoma

Intraductal papillary mucinous neoplasms (IPMN) have the potential to progress to pancreatic ductal adenocarcinoma (PDAC). As with any progression to malignancy, there are a variety of genetic and metabolic changes, as well as other disruptions to the cellular microenvironment including immune alterations and inflammation, that can contribute to tumorigenesis. Previous studies further characterized these alterations, revealing changes in lipid and glucose metabolism, and signaling pathways that mediate the progression of IPMN to PDAC. With the increased diagnosis of IPMNs and pancreatic cysts on imaging, the opportunity to attenuate risk with the removal of high-risk lesions is possible with the understanding of what factors accelerate malignant progression and how they can be clinically utilized to determine the level of dysplasia and stratify the risk of progression. Here, we reviewed the genetic, metabolic, inflammatory, and immunologic pathways regulating the progression of IPMN to PDAC.

Pancreatic Cystic Neoplasms: Translating Guidelines into Clinical Practice

A combination of several factors, including the increasing use of cross-sectional imaging and an aging population, has led to pancreatic cystic lesions (PCLs) becoming the most detected incidental pancreatic lesions. Accurate diagnosis and risk stratification of PCLs is challenging. In the last decade, several evidence-based guidelines have been published addressing the diagnosis and management of PCLs. However, these guidelines cover different subsets of patients with PCLs and offer varying recommendations regarding diagnostic assessment, surveillance, and surgical resection. Further, recent studies comparing the accuracy of various guidelines have reported significant variations in the rate of missed cancer versus unnecessary surgical resections. In clinical practice, it is challenging to decide which guideline to follow specifically. This article reviews the varying recommendations of the major guidelines and results of comparative studies, provides an overview of newer modalities not included in the guidelines, and offers perspectives on translating the guidelines into clinical practice.

A Review of Endoscopic Ultrasound-Guided Chemoablative Techniques for Pancreatic Cystic Lesions

Pancreatic cystic lesions (PCLs) are known precursors to pancreatic cancer, one of the deadliest types of cancer worldwide. Surgical removal or pancreatectomies remain the central approach to managing precancerous high-risk PCLs. Endoscopic ultrasound (EUS)-guided therapeutic management of PCLs is a novel management strategy for patients with prohibitive surgical risks. Various ablation techniques have been explored in previous studies utilizing EUS-guided fine needle injection (FNI) of alcohol and chemotherapeutic agents. This review article focuses on EUS-FNI and chemoablation, encompassing the evolution of chemoablation, pancreatic cyst selection, chemotherapy drug selection, including novel agents, and a discussion of its safety and efficacy.

Comparison of Clinical and Imaginal Features According to the Pathological Grades of Dysplasia in Branch-Duct Intraductal Papillary Mucinous Neoplasm (BD-IPMN) for Personalized Medicine

Background: In patients with BD-IPMN, surgical indications have been focused on finding malignant lesions (HGD, high-grade dysplasia/IC, invasive carcinoma). The aim of this study was to compare the preoperative factors that distinguish HGD from LGD (low-grade dysplasia) and HGD from IC to find the optimal pathologic target for surgery according to individuals, considering surgical risks and outcomes. Methods: We retrospectively analyzed 232 patients with BD-IPMN diagnosed based on pathology after surgery and preoperative images. The primary outcome was identifying preoperative factors distinguishing HGD from LGD, and HGD from IC. Results: In patients with LGD/HGD, a solid component or an enhancing mural nodule ≥ 5 mm (OR = 9.29; 95% CI: 3.3−54.12; p < 0.000) and thickened/enhancing cyst walls (OR = 6.95; 95% CI: 1.68−33.13; p = 0.008) were associated with HGD. In patients with malignant lesions (HGD/IC), increased serum CA 19-9 (OR = 12.59; 95% CI: 1.81−87.44; p = 0.006) was associated with IC. Conclusions: The predictive factors for HGD were the presence of a solid component or an enhancing mural nodule ≥ 5 mm and thickened/enhancing cyst walls compared with LGD, and if accompanied by increased CA 19-9, it might be necessary to urgently evaluate the lesion due to the possibility of progression to IC. Based on this finding, we need to find HGD as the optimal pathologic target for surgery to improve survival in low-surgical-risk patients, and IC could be assumed to be the optimal pathologic target for surgery in high-surgical-risk patients because of high morbidity and mortality associated with surgery.

Pancreatic Cystic Lesions: A Focused Review on Cyst Clinicopathological Features and Advanced Diagnostics

Macroscopic, endomicroscopic, and histologic findings and correlation are an integral part of the diagnostic evaluation of pancreatic cystic lesions (PCLs), as complementing morphologic features seen by different specialties are combined to contribute to a final diagnosis. However, malignancy risk stratification of PCLs with worrisome features can still be challenging even after endoscopic ultrasound guided-fine needle aspiration (EUS-FNA) with cytological evaluation. This review aims to summarize cyst clinicopathological features from the pathologists' perspective, coupled with knowledge from advanced diagnostics-confocal laser endomicroscopy and cyst fluid molecular analysis, to demonstrate the state-of-art risk stratification of PCLs. This review includes illustrative photos of surgical specimens, endomicroscopic and histologic images, and a summary of cyst fluid molecular markers.

Historical perspective on needle development: From the past to the future

With the introduction of EUS, endoscopy was no longer limited to luminal indications. However, the method was unable to distinguish malignant from benign lesions. Consequently, needles designed for tissue acquisition under EUS-guidance was designed. Initially, the needles were designed for fine needle aspiration (FNA); nevertheless, with increased requirement for the precured tissue in terms of quality and quantity, newly design needles aimed at obtaining tissue cores for histological assessment were developed. Recent studies demonstrate superiority of these fine needle biopsy needles (FNB) compared to FNA needles.

Accuracy and agreement of a large panel of endosonographers for endomicroscopy-guided virtual biopsy of pancreatic cystic lesions

BACKGROUND

Although emerging data evidences that EUS-guided needle-based confocal laser endomicroscopy (nCLE) accurately diagnoses pancreatic cystic lesions (PCLs), there are a lack of interobserver agreement (IOA) studies utilizing reference histopathological diagnosis and for specific PCL subtypes. Hence, we sought to assess the IOA, intra-observer reliability (IOR), and diagnostic performance of EUS-nCLE using a large cohort of patients with histopathological diagnosis amongst a broad panel of international observers.

METHODS

EUS-nCLE videos (n = 76) of subjects with PCLs [intraductal papillary mucinous neoplasm (IPMN), mucinous cystic neoplasm (MCN), serous cystadenoma (SCA), pseudocyst, and cystic-neuroendocrine tumors/solid pseudopapillary neoplasm (cystic-NET/SPN)], simulating clinical prevalence rates were obtained from 3 prospective studies. An international panel of 13 endosonographers with nCLE experience, blinded to all PCL data, evaluated the video library twice with a two-week washout for PCL differentiation (mucinous vs. non-mucinous) and subtype diagnosis.

RESULTS

The IOA (κ = 0.82, 95% CI 0.77-0.87) and IOR (κ = 0.82, 95% CI 0.78-0.85) were "almost perfect" to differentiate mucinous vs. non-mucinous PCLs. For PCL subtype, IOA was highest for SCA (almost perfect; κ = 0.85), followed by IPMN (substantial, κ = 0.72), and cystic-NET/SPN (substantial, κ = 0.73). The IOA was moderate for MCN (κ = 0.47), and pseudocyst (κ = 0.57). Compared to histopathology, observers differentiated mucinous vs. non-mucinous PCLs with high accuracy (94.8%, 95% CI 93.3-96.1). For detecting specific PCLs subtypes, EUS-nCLE was highly accurate in diagnosing non-mucinous cysts (SCA: 98%; cystic-NET/SPN: 96%; pseudocyst: 96%) and slightly less accurate for mucinous lesions (IPMN: 86%; MCN: 84%).

CONCLUSION

Diagnosis of PCLs by EUS-nCLE guided virtual biopsy is very accurate and reliable for the most prevalent pancreatic cysts in clinical practice.

Deep Learning for Automatic Differentiation of Mucinous versus Non-Mucinous Pancreatic Cystic Lesions: A Pilot Study

Endoscopic ultrasound (EUS) morphology can aid in the discrimination between mucinous and non-mucinous pancreatic cystic lesions (PCLs) but has several limitations that can be overcome by artificial intelligence. We developed a convolutional neural network (CNN) algorithm for the automatic diagnosis of mucinous PCLs. Images retrieved from videos of EUS examinations for PCL characterization were used for the development, training, and validation of a CNN for mucinous cyst diagnosis. The performance of the CNN was measured calculating the area under the receiving operator characteristic curve (AUC), sensitivity, specificity, and positive and negative predictive values. A total of 5505 images from 28 pancreatic cysts were used (3725 from mucinous lesions and 1780 from non-mucinous cysts). The model had an overall accuracy of 98.5%, sensitivity of 98.3%, specificity of 98.9% and AUC of 1. The image processing speed of the CNN was 7.2 ms per frame. We developed a deep learning algorithm that differentiated mucinous and non-mucinous cysts with high accuracy. The present CNN may constitute an important tool to help risk stratify PCLs.

Comparison of Society Guidelines for the Management and Surveillance of Pancreatic Cysts: A Review

Importance

The identification of incidental pancreas cystic lesions (PCLs) has increased in recent decades with the expanded use and improved sensitivity of cross-sectional imaging. Because the overall risk of malignancy associated with PCLs is low, yet the relative morbidity of pancreatic surgery is high, evidence-based guidelines are necessary for appropriate surveillance and management. Therefore, this article provides a review of existing guidelines regarding surveillance and management of PCLs and highlights recent advances in the diagnostic evaluation of cysts and the postresection management of mucinous lesions.

Observations

There are 5 main guidelines related to the management of PCLs: the American Gastrointestinal Association (AGA) guidelines, the American College of Gastroenterology (ACG) guidelines, the American College of Radiology (ACR) recommendations, the European evidence-based guidelines, and the International Association of Pancreatology (IAP)/Fukuoka guidelines. These guidelines are based on retrospective studies that do not account or control for most tumor- and patient-specific factors. These guidelines also vary in scope, recommendations for surgical resection vs surveillance, as well as duration and type of follow-up.

Conclusions and Relevance

PCL guidelines should be viewed within the context of the data limitations on which they are based. PCL subtype-specific guidelines on surveillance and treatment are needed. In the future, the integration of cyst-specific genomic analysis, as well as evolutions in advanced diagnostic tools, such as cyst fluid next-generation sequencing and EUS-guided confocal laser endomicroscopy, may also better inform treatment guidelines. Owing to the current low-quality evidence on which many guidelines are based and the inherent morbidity of pancreas surgery, it is imperative that patients with PCLs are referred to institutions with advanced diagnostics and a multidisciplinary approach to patient surveillance and management.

MRI-Based Pancreatic Atrophy Is Associated With Malignancy or Invasive Carcinoma in Intraductal Papillary Mucinous Neoplasm

Background

Abrupt change in the caliber of the main pancreatic duct (MPD) with distal pancreatic atrophy (PA) was considered as one of worrisome features in the International Association of Pancreatology guideline and American College of Gastroenterology guideline for the management of intraductal papillary mucinous neoplasms (IPMNs). However, this feature was not included in other guidelines. Moreover, the association between PA alone and malignancy in IPMNs has not been fully evaluated. In the present study, we investigated the role of image-based PA in identifying malignant IPMNs or invasive carcinoma.

Methods

A total of 186 patients with IPMNs were included for analysis. The tumor size, location, MPD diameter, presence of a mural nodule (MN), and PA were evaluated using magnetic resonance imaging. Demographic information and serum carbohydrate antigen 19-9 and carcinoembryonic antigen (CEA) levels were also collected. IPMNs with high-grade dysplasia and associated invasive carcinoma were regarded as malignant IPMNs.

Results

PA was observed in 34 cases (18.3%). The occurrence of malignant IPMNs or invasive carcinoma in patients with PA were significantly higher than in those without PA (52.9% vs. 22.3%; 44.1% vs. 8.9%, all P < 0.01). Multivariate logistic regression analysis showed that PA was an independently associated factor for malignant IPMNs [odds ratio (OR) = 2.69, 95% confidence interval (CI): 1.07-6.78] or invasive carcinoma (OR = 7.78, 95%CI: 2.62-23.10) after modified with confounders. Subgroup analysis in MPD-involved IPMNs also indicated that PA was an independently associated factor for invasive carcinoma (OR = 9.72, 95%CI: 2.43-38.88). PA had a similar performance with MPD plus MN [the area under the curve (AUC) was both 0.71] in identifying malignancy. PA had a higher performance in identifying invasive carcinoma in MPD-involved IPMNs than MN (AUC = 0.71 vs. 0.65, P = 0.02).

Conclusion

Our data showed that imaging-based PA was associated with malignancy or invasive carcinoma regardless of abrupt change in the caliber of MPD in IPMNs. PA had an acceptable performance in identifying malignant IPMNs.

State-of-the-Art Update of Pancreatic Cysts

Andrew Canakis.

Advanced Imaging of the Biliary System and Pancreas

Despite advances in noninvasive techniques for imaging the pancreaticobiliary system, several disease processes including indeterminate biliary strictures as well as neuroendocrine tumors, inflammatory pseudotumors, and complex cysts of the pancreas remain difficult to characterize. New endoscopic imaging technologies have emerged to address these challenges. Cholangioscopy and intraductal ultrasound (IDUS) are powerful tools to characterize subtle biliary concretions and strictures. Confocal Laser Endomicroscopy (CLE) and Optical Coherence Tomography (OCT) are emerging approaches for the most difficult biliary lesions. Contrast harmonic endoscopic ultrasound (CH-EUS), elastography, and 3D-EUS are improving the approach to subtle pancreatic lesions, particularly in the context of indeterminate tissue sampling. Pancreatoscopy, pancreatic IDUS, and intracystic CLE hold promise to further improve the assessment of pancreatic cysts. We aim to comprehensively review the emerging clinical evidence for these innovative endoscopic imaging techniques.

Intracystic Glucose and Carcinoembryonic Antigen in Differentiating Histologically Confirmed Pancreatic Mucinous Neoplastic Cysts

INTRODUCTION

Differentiating mucinous neoplastic pancreatic cysts (MNPC) from cysts without malignant potential can be challenging. Guidelines recommend using fluid carcinoembryonic antigen (CEA) to differentiate MNPC; however, its sensitivity and specificity vary widely. Intracystic glucose concentration has shown promise in differentiating MNPC, but data are limited to frozen specimens and cohorts of patients without histologic diagnoses. This study aimed to compare glucose and CEA concentrations in differentiating MNPC using fresh fluid obtained from cysts with confirmatory histologic diagnoses.

METHODS

This multicenter cohort study consisted of patients undergoing endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) for pancreatic cysts during January 2013-May 2020. Patients were included if the cyst exhibited a histologic diagnosis and if both CEA and glucose were analyzed from fresh fluid. Receiver operating curve (ROC) characteristics were analyzed, and various diagnostic parameters were compared.

RESULTS

Ninety-three patients, of whom 59 presented with MNPC, met the eligibility criteria. The area under the receiver operating curve (AUROC) was 0.96 for glucose and 0.81 for CEA (difference 0.145, P = 0.003). A CEA concentration of ≥192 ng/mL had sensitivity of 62.7% and specificity of 88.2% in differentiating MNPC, whereas glucose concentration of ≤25 mg/dL had sensitivity and specificity of 88.1% and 91.2%, respectively.

DISCUSSION

Intracystic glucose is superior to CEA concentration for differentiating MNPC when analyzed from freshly obtained fluid of cysts with histologic diagnoses. The advantage of glucose is augmented by its low cost and ease of implementation, and therefore, its widespread adoption should come without barriers. Glucose has supplanted CEA as the best fluid biomarker in differentiating MNPC.

Recent advances in the diagnostic evaluation of pancreatic cystic lesions

Pancreatic cystic lesions (PCLs) are becoming more prevalent due to more frequent abdominal imaging and the increasing age of the general population. It has become crucial to identify these PCLs and subsequently risk stratify them to guide management. Given the high morbidity associated with pancreatic surgery, only those PCLs at high risk for malignancy should undergo such treatment. However, current diagnostic testing is suboptimal at accurately diagnosing and risk stratifying PCLs. Therefore, research has focused on developing new techniques for differentiating mucinous from non-mucinous PCLs and identifying high risk lesions for malignancy. Cross sectional imaging radiomics can potentially improve the predictive accuracy of primary risk stratification of PCLs at the time of detection to guide invasive testing. While cyst fluid glucose has reemerged as a potential biomarker, cyst fluid molecular markers have improved accuracy for identifying specific types of PCLs. Endoscopic ultrasound guided approaches such as confocal laser endomicroscopy and through the needle microforceps biopsy have shown a good correlation with histopathological findings and are evolving techniques for identifying and risk stratifying PCLs. While most of these recent diagnostics are only practiced at selective tertiary care centers, they hold a promise that management of PCLs will only get better in the future.

Efficacy and safety of EUS-guided through-the-needle microforceps biopsy sampling in categorizing the type of pancreatic cystic lesions

BACKGROUND AND AIMS

EUS-guided through-the-needle biopsy sampling (EUS-TTNB) using microbiopsy forceps is performed for the accurate diagnosis of pancreatic cystic lesions (PCLs). However, there are no standardized protocols for this procedure, and the amount of data on its efficacy is limited. Here, we evaluated the feasibility, efficacy, and safety of EUS-TTNB in categorizing the types of PCLs and identified the factors associated with diagnostic failure.

METHODS

The prospectively collected and maintained EUS-TTNB database at Asan Medical Center was reviewed to identify patients with PCLs who underwent EUS-TTNB between January 2019 and January 2021. The primary outcomes were technical success, diagnostic yield, and adverse events. Factors contributing to diagnostic failure and the discrepancies in the diagnosis made by conventional modalities (ie, EUS morphology, cross-sectional imaging, and cystic fluid analysis) were also evaluated.

RESULTS

Forty-five patients were analyzed. EUS-TTNB was successfully performed in all patients (technical success, 100%). Histologic diagnosis of PCLs was made in 37 patients (diagnostic yield, 82%). When comparing EUS-TTNB with a presumptive diagnosis, EUS-TTNB changed the diagnosis in 10 patients in terms of the categorization of the types of PCLs. The diagnostic yield was significantly higher in those who had 4 or more visible biopsy specimens per session (93%) than in those with fewer than 4 visible biopsy specimens per session (67%; P = .045). During follow-up, 3 patients (7%) experienced adverse events (2 acute pancreatitis, 1 intracystic bleeding), and no life-threatening adverse event occurred.

CONCLUSIONS

EUS-TTNB showed high technical feasibility, diagnostic yield, and good safety profile. EUS-TTNB may improve the categorization of the types of PCLs. Studies with standardized procedure protocols are needed to reduce the diagnostic failure for the types of PCLs.

Confocal Laser Endomicroscopy in the Diagnosis of Biliary and Pancreatic Disorders: A Systematic Analysis

Background/Aims

Endoscopic visualization of the microscopic anatomy can facilitate the real-time diagnosis of pancreatobiliary disorders and provide guidance for treatment. This study aimed to review the technique, image classification, and diagnostic performance of confocal laser endomicroscopy (CLE).

Methods

We conducted a systematic review of CLE in pancreatic and biliary ducts of humans, and have provided a narrative of the technique, image classification, diagnostic performance, ongoing research, and limitations.

Results

Probe-based CLE differentiates malignant from benign biliary strictures (sensitivity, ≥89%; specificity, ≥61%). Needle-based CLE differentiates mucinous from non-mucinous pancreatic cysts (sensitivity, 59%; specificity, ≥94%) and identifies dysplasia. Pancreatitis may develop in 2-7% of pancreatic cyst cases. Needle-based CLE has potential applications in adenocarcinoma, neuroendocrine tumors, and pancreatitis (chronic or autoimmune). Costs, catheter lifespan, endoscopist training, and interobserver variability are challenges for routine utilization.

Conclusions

CLE reveals microscopic pancreatobiliary system anatomy with adequate specificity and sensitivity. Reducing costs and simplifying image interpretation will promote utilization by advanced endoscopists.

Contrast-enhanced EUS for the characterization of mural nodules within pancreatic cystic neoplasms: systematic review and meta-analysis

BACKGROUND AND AIMS

Pancreatic cystic neoplasms (PCNs) carry a considerable malignancy risk. Along with main duct dilation, the presence of enhanced mural nodules represents a significant risk factor for malignancy. Several articles assessed the role of contrast-enhanced EUS (CE-EUS) for the identification of malignant features in mural nodules. We evaluate the pooled diagnostic performance of CE-EUS for the identification of high-grade dysplasia or invasive carcinoma among mural nodules in PCNs.

METHODS

A systematic review (Medline, PubMed, EMBASE) and meta-analysis were conducted. Subgroup analysis was used to assess the usefulness of a dedicated contrast-harmonic (CH-EUS). The primary outcome was pooled sensitivity for identification of high-grade dysplasia or invasive carcinoma.

RESULTS

Ten studies (532 patients) were included. Pooled sensitivity of CE-EUS was 88.2% (95% confidence interval [CI], 82.7%-92.5%), specificity 79.1% (95% CI, 74.5%-83.3%), and diagnostic accuracy 89.6% (95% CI, 83.4%-95.8%). Eight studies (320 patients) were conducted using CH-EUS: pooled sensitivity increased to 97.0% (95% CI, 92.5%-99.2%), specificity to 90.4% (95% CI, 85.2%-94.2%), and diagnostic accuracy to 95.6% (95% CI, 92.6%-98.7%). At 42% disease prevalence (pretest probability), a positive CH-EUS increased the disease probability to 88%, whereas a negative test decreased the disease probability to 2%. The number needed to diagnose was 1.5 (95% CI, 1.7-1.3) for CE-EUS and just 1.2 (95% CI, 1.3-1.1) for CH-EUS.

CONCLUSIONS

This study provided robust evidence on CE-EUS value for the characterization of mural nodules within PCNs. A dedicated contrast-harmonic mode, namely CH-EUS, provided an increased diagnostic yield in the identification and characterization of malignant mural nodules.

Management of pancreatic cysts and guidelines: what the gastroenterologist needs to know

The prevalence of pancreatic cysts has increased significantly over the last decade, partly secondary to increased quality and frequency of cross-sectional imaging. While the majority never progress to cancer, a small number will and need to be followed. The management of pancreatic cysts can be both confusing and intimidating due to the multiple guidelines with varying recommendations. Despite the differences in the specifics of the guidelines, they all agree on several high-risk features that should get the attention of any clinician when assessing a pancreatic cyst: presence of a mural nodule or solid component, dilation of the main pancreatic duct (or presence of main duct intraductal papillary mucinous neoplasm), pancreatic cyst size ⩾3–4 cm, or positive cytology on pancreatic cyst fluid aspiration. Other important criteria to consider include rapid cyst growth (⩾5 mm/year), elevated serum carbohydrate antigen 19-9 levels, new-onset diabetes mellitus, or acute pancreatitis thought to be related to the cystic lesion.

High performance in risk stratification of intraductal papillary mucinous neoplasms by confocal laser endomicroscopy image analysis with convolutional neural networks (with video)

BACKGROUND AND AIMS

EUS-guided needle-based confocal laser endomicroscopy (EUS-nCLE) can differentiate high-grade dysplasia/adenocarcinoma (HGD-Ca) in intraductal papillary mucinous neoplasms (IPMNs) but requires manual interpretation. We sought to derive predictive computer-aided diagnosis (CAD) and artificial intelligence (AI) algorithms to facilitate accurate diagnosis and risk stratification of IPMNs.

METHODS

A post hoc analysis of a single-center prospective study evaluating EUS-nCLE (2015-2019; INDEX study) was conducted using 15,027 video frames from 35 consecutive patients with histopathologically proven IPMNs (18 with HGD-Ca). We designed 2 CAD-convolutional neural network (CNN) algorithms: (1) a guided segmentation-based model (SBM), where the CNN-AI system was trained to detect and measure papillary epithelial thickness and darkness (indicative of cellular and nuclear stratification), and (2) a reasonably agnostic holistic-based model (HBM) where the CNN-AI system automatically extracted nCLE features for risk stratification. For the detection of HGD-Ca in IPMNs, the diagnostic performance of the CNN-CAD algorithms was compared with that of the American Gastroenterological Association (AGA) and revised Fukuoka guidelines.

RESULTS

Compared with the guidelines, both n-CLE-guided CNN-CAD algorithms yielded higher sensitivity (HBM, 83.3%; SBM, 83.3%; AGA, 55.6%; Fukuoka, 55.6%) and accuracy (SBM, 82.9%; HBM, 85.7%; AGA, 68.6%; Fukuoka, 74.3%) for diagnosing HGD-Ca, with comparable specificity (SBM, 82.4%; HBM, 88.2%; AGA, 82.4%; Fukuoka, 94.1%). Both CNN-CAD algorithms, the guided (SBM) and agnostic (HBM) models, were comparable in risk stratifying IPMNs.

CONCLUSION

EUS-nCLE-based CNN-CAD algorithms can accurately risk stratify IPMNs. Future multicenter validation studies and AI model improvements could enhance the accuracy and fully automatize the process for real-time interpretation.

Efficacy of EUS-guided needle-based confocal laser endomicroscopy in the diagnosis of pancreatic lesions: A systematic review and meta-analysis

Background and Objectives:

Needle-based confocal laser endomicroscopy (nCLE) is a procedure in which an AQ-Flex nCLE mini-probe is passed through an EUS-FNA needle into a pancreatic lesion to enable subsurface in vivo tissue analysis. In this study, we conducted a systematic review and meta-analysis of nCLE for the diagnosis of pancreatic lesions.

Materials and Methods:

We conducted a comprehensive search of several databases and conference proceedings, including PubMed, EMBASE, Google-Scholar, MEDLINE, SCOPUS, and Web of Science databases (earliest inception to March 2020). The primary outcomes assessed the pooled rate of diagnostic accuracy for nCLE and the secondary outcomes assessed the pooled rate of sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and adverse events (AE) of nCLE to diagnose premalignant/malignant pancreatic lesions.

Results:

Eleven studies on 443 patients were included in our analysis. The pooled rate of diagnostic accuracy of EUS nCLE was 83% (95 confidence interval [CI] = 79–87; I² = 0). The pooled rate of sensitivity, specificity, PPV and NPV of EUS nCLE was 85.29% (95% CI = 76.9–93.68; I² = 85%), 90.49% (95% CI = 82.24–98.74; I² = 64%), 94.15% (95% CI = 88.55–99.76; I² = 68%), and 73.44% (95% CI = 60.16–86.72; I² = 93%), respectively. The total AE rate was 5.41% (±5.92) with postprocedure pancreatitis being the most common AE at 2.28% (±3.73).

Conclusion:

In summary, this study highlights the rate of diagnostic accuracy, sensitivity, specificity, and PPV for distinguishing premalignant/malignant lesions. Pancreatic lesions need to be further defined with more validation studies to characterize CLE diagnosis criteria and to evaluate its use as an adjunct to EUS-FNA.

Pre-Operative Imaging and Pathological Diagnosis of Localized High-Grade Pancreatic Intra-Epithelial Neoplasia without Invasive Carcinoma

Pancreatic ductal adenocarcinoma (PDAC) arises from precursor lesions, such as pancreatic intra-epithelial neoplasia (PanIN) and intraductal papillary mucinous neoplasm (IPMN). The prognosis of high-grade precancerous lesions, including high-grade PanIN and high-grade IPMN, without invasive carcinoma is good, despite the overall poor prognosis of PDAC. High-grade PanIN, as a lesion preceding invasive PDAC, is therefore a primary target for intervention. However, detection of localized high-grade PanIN is difficult when using standard radiological approaches. Therefore, most studies of high-grade PanIN have been conducted using specimens that harbor invasive PDAC. Recently, imaging characteristics of high-grade PanIN have been revealed. Obstruction of the pancreatic duct due to high-grade PanIN may induce a loss of acinar cells replaced by fibrosis and lobular parenchymal atrophy. These changes and additional inflammation around the branch pancreatic ducts (BPDs) result in main pancreatic duct (MPD) stenosis, dilation, retention cysts (BPD dilation), focal pancreatic parenchymal atrophy, and/or hypoechoic changes around the MPD. These indirect imaging findings have become important clues for localized, high-grade PanIN detection. To obtain pre-operative histopathological confirmation of suspected cases, serial pancreatic-juice aspiration cytologic examination is effective. In this review, we outline current knowledge on imaging characteristics of high-grade PanIN.

A new needle-based confocal laser endomicroscopy pattern of malignant pancreatic mucinous cystic lesions (with video)

Background and Objectives:

The diagnosis of malignant pancreatic cystic lesions (PCLs) remains challenging. Needle-based confocal laser endomicroscopy (nCLE) is an emerging promising imaging technique capable of real-time in vivo microscopic imaging of the cyst wall. We aimed to develop and validate a new nCLE diagnostic criteria for malignant mucinous cystic lesions (MLs).

Methods:

Patients referred for EUS-FNA of indeterminate PCLs with at least one worrisome features according to Fukouka consensus were consecutively prospectively enrolled from July 2016 to July 2018. The final diagnosis was based on surgical histology, cytopathology, or committee consensus. Five investigators nonblindly reviewed nCLE features and identified potential diagnostic feature for malignant MLs, which was also reviewed in histology imaging accordingly. Furthermore, the nCLE diagnostic feature was evaluated with an independent nCLE dataset by two investigators in a double-blind manner.

Results:

A nCLE pattern of dark aggregates of neoplastic cells was identified as diagnostic for MLs, which was consistent with histological findings of irregular branching and budding in malignant MLs. An independent validation revealed that the accuracy, sensitivity, and specificity of this feature for the diagnosis of malignant MLs were 94%, 75%, and 100%, respectively.

Conclusion:

The new nCLE criterion is promising for diagnosis of malignant MLs which warrants further confirmation in large cohort.

Intraductal Pancreatic Mucinous Neoplasms: A Tumor-Biology Based Approach for Risk Stratification

Pancreatic ductal adenocarcinoma is one of the most lethal human cancers. Its precursor lesions include pancreatic intra-epithelial neoplasia, mucinous cystic neoplasm, and intraductal papillary mucinous neoplasm (IPMN). IPMNs usually present as an incidental finding at imaging in 2.6% of the population and, according to the degree of dysplasia, they are classified as low- or high-grade lesions. Since the risk of malignant transformation is not accurately predictable, the management of these lesions is based on morphological and clinical parameters, such as presence of mural nodule, main pancreatic duct dilation, presence of symptoms, or high-grade dysplasia. Although the main genetic alterations associated to IPMNs have been elucidated, they are still not helpful for disease risk stratification. The growing body of genomic and epigenomic studies along with the more recent development of organotypic cultures provide the opportunity to improve our understanding of the malignant transformation process, which will likely deliver biomarkers to help discriminate between low- and high-risk lesions. Recent insights on the topic are herein summarized.

New Devices for Endoscopic Treatments in Gastroenterology: A Narrative Review

Endoscopy is in a period of continuous innovations in terms of image quality, endoscopes, post-processing software and lastly, application of Artificial Intelligence. Therapeutic boundaries have expanded, widening the grey zone between endoscopy and surgery, and increasing endoscopic approaches in clinical scenarios where, until a few years ago, surgery was the only option. New scopes and accessories have made it easier to access critical areas such as the biliary tree and the small bowel intestine. In the field of hepato-pancreato-biliary endoscopy (HPB), it is now possible to directly access the biliary ducts or cystic lesions though dedicated stents and scopes, rather than having to rely only on fluoroscopy and ultrasound, increasing the diagnostic and therapeutic options by applying a three-dimensional approach. This narrative review will give an overview of some of the most relevant emerging fields in luminal and HPB endoscopy, highlighting advantages and main limitations of the techniques, and providing considerations for future development.

The Role of Needle-Based Confocal Laser Endomicroscopy in the Evaluation of Pancreatic Cystic Lesions: A Systematic Review

The prevalence of pancreatic cystic lesions (PCLs) has increased recently due to the increased use of cross-sectional abdominal imaging and the ageing global population. Current diagnostic techniques are inadequate to distinguish between PCLs that require surgery, close surveillance, or expectant management. This has resulted in increased morbidity from both inappropriately aggressive and conservative management strategies. Needle-based confocal laser endomicroscopy (nCLE) has allowed microscopic examination and visual delineation of the surface epithelium of PCLs. Landmark studies in this decade have correlated nCLE and histological findings and identified characteristics differentiating various types of PCLs. Subsequent studies have confirmed the high diagnostic yield of nCLE and its diagnostic utility in PCLs with an equivocal diagnosis. Moreover, nCLE has been shown to improve the diagnostic yield of PCLs. This will help avoid unnecessary pancreatic surgery, which carries significant morbidity and mortality risks. The early detection of high-grade dysplasia in PCLs will provide early surgical treatment and improve outcomes for pancreatic cancer. Despite the high upfront cost of nCLE, the improved diagnostic accuracy and resultant appropriate management have resulted in improved cost effectiveness. Refining the procedure technique and limiting the procedure length have significantly improved the safety of nCLE. A structured training program and device improvements to allow more complete mapping of the pancreatic cyst epithelium will be crucial for the widespread adoption of this promising technology.