Appraisal of needle-based confocal laser endomicroscopy in the diagnosis of pancreatic cysts

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.

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.

Confocal endomicroscopy for evaluation of pancreatic cystic lesions: a systematic review and international Delphi consensus report

Background and study aims  The aim of thi systematic review and consensus report is to standardize the practice of endoscopic ultrasound (EUS-guided needle-based confocal laser endomicroscopy (nCLE) for pancreatic cystic lesion (PCL) evaluation. Methods  We performed an international, systematic, evidence-based review of the applications, outcomes, procedural processes, indications, training, and credentialing of EUS-nCLE in management of PCLs. Based on available clinical evidence, preliminary nCLE consensus statements (nCLE-CS) were developed by an international panel of 15 experts in pancreatic diseases. These statements were then voted and edited by using a modified Delphi approach. An a priori threshold of 80 % agreement was used to establish consensus for each statement. Results  Sixteen nCLE-CS were discussed. Thirteen (81 %) nCLE-CS reached consensus addressing indications (non-communication PCL meeting criteria for EUS-FNA or with prior non-diagnostic EUS-FNA), diagnostic outcomes (improved accuracy for mucinous PCLs and serous cystadenomas with substantial interobserver agreement of image patterns), low incidence of adverse events (fluorescein-associated and pancreatitis), procedural processes (nCLE duration, manipulation of needle with probe), and training (physician knowledge and competence). Conclusion  Based on a high level of agreement pertaining to expert consensus statements, this report standardizes the practice of EUS-nCLE. EUS-nCLE should be systematically considered when EUS-FNA is indicated for PCL evaluation.

Diagnostic approaches for pancreatic cystic lesions

BACKGROUND

Cystic lesions of the pancreas (PCLs) may be inflammatory or proliferative and making an accurate and timely pre-operative diagnosis remains a significant clinical challenge. This is principally due to the heterogeneity of the pathological processes involved. PCLs constitute an entity with diverse histology and although infrequent, the possible potential for malignant transformation of these lesions and the opportunity for curative surgery mandates that our diagnostic approaches are up to date and evidence based. In addition, improved diagnostic accuracy is crucial to prevent unnecessary surgical procedures with the inevitable associated morbidity.

METHODS

This narrative review examines the current diagnostic benchmarks and identifies novel diagnostic techniques that warrant further consideration, a number of which are beginning to be included in routine clinical practice when these PCLs are being investigated. A computerized search was made of MEDLINE, EMBASE and PubMed using the search words 'diagnostic approaches to pancreatic cystic lesions'. All relevant articles in English language or with an English abstract were retrieved and additionally cross referenced.

CONCLUSION

The increasing accuracy of available imaging techniques together with the wider availability of endoluminal ultrasound and the development of additional novel methods to assess PCLs presents an opportunity to significantly improve the pre-operative diagnosis rate. This is essential to classify the type of PCL and hence guide the management particularly with lesions where there is a likelihood of progression to more serious pathology. We have highlighted the need for a comprehensive and standardized algorithm for the diagnosis and management of PCLs.

Confocal endomicroscopy for the diagnosis of pancreatic lesions

Confocal endomicroscopy (EMC) is a thriving technology that allows real-time and non-invasive imaging in vivo. EMC demonstrated its effectiveness to differentiate neoplastic from normal tissue and to search dysplasia. In addition to the significant developments of this technique in Barrett oesophagus, celiac disease, characterization of colonic polyps, or monitoring of chronic inflammatory bowel disease, EMC is currently developing in bilio-pancreatic pathology. Indeed, it is currently used to characterize biliary stenosis as well as pancreatic lesions (especially cystic). The aim of our study was to evaluate through a review of the literature the value of this technique in the characterization of pancreatic lesions.

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 ultrasonography for the evaluation of pancreatic cystic neoplasms

Endoscopic ultrasonography (EUS) is a modality with high spatial resolution that enables comprehensive observation of the entire pancreas and plays an important role in the diagnosis of pancreatic lesions. Recent advances in diagnostic imaging methods such as ultrasound, computed tomography, and magnetic resonance imaging have increased the incidental detection of pancreatic cystic lesions (PCLs). EUS has been recognized as an essential diagnostic method for the detection and evaluation of PCLs. EUS has two important roles: as a detailed (high-resolution) imaging diagnostic method and as an approach for collecting cyst fluid content by EUS-guided fine needle aspiration for pathological diagnosis or biomarker evaluation. Furthermore, in recent years, the usefulness of contrast-enhanced EUS for the differential diagnosis of PCLs or evaluation of grade of malignancy, and a novel imaging technique called needle-based confocal laser endomicroscopy to observe intraductal structures through a needle, has been reported. An understanding of the morphological characteristics of PCLs depicted by ultrasound imaging and of the benefits and limitations of EUS diagnosis in daily practice is needed.

The Impact of Repeating Endosonography with Confocal Endomicroscopy for the Diagnosis of Cystic Neuroendocrine Tumor

Cystic pancreatic neuroendocrine tumors represent around 13% of all neuroendocrine tumors (Hurtado-Pardo 2017). There has been an increase in the incidence of cases due to improvement in imaging modalities. This is a case of a 68-year-old male with the incidental finding of a pancreatic cyst on CT. Initial Endoscopic Ultrasound with Fine Needle Aspiration (EUS-FNA) showed sonographic and cytology features suggestive of a pancreatic pseudocyst. However the cyst persisted with no change in size after aspiration leading to a follow-up EUS- FNA, which was combined with needle based confocal laser endomicroscopy (nCLE). The nCLE features were consistent with a cystic pancreatic neuroendocrine tumor, which was later confirmed on histology after surgical resection.

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

BACKGROUND AND STUDY AIMS

 Endoscopic ultrasound fine-needle aspiration (EUS-FNA) is a keystone in diagnosing and staging of pancreatic masses. Recently, a microfiber that can pass through a 19-gauge needle has been introduced for confocal laser endomicroscopy (nCLE). The aims of this study were to evaluate the diagnostic value and the reproducibility of nCLE criteria for solid malignant lesions.

PATIENTS AND METHODS

 This prospective dual-center study included patients with pancreatic masses suspicious of malignancy referred for EUS-FNA. Endomicroscopic imaging was performed under EUS-guidance until organ-specific structures were obtained. Afterwards, standard cytology was obtained and patients were followed for up to 12 months. All nCLE parameters included in former studies were correlated with the final diagnosis (dark lobular structures/normal acinar cells, dark cell aggregates > 40 µm, dilated irregular vessels with fluorescein leakage, fine white fibrous bands, small black cell movements, pseudoglandular structures). Finally, three CLE novices and three CLE experts assessed the unedited movies from all patients.

RESULTS

 Twenty-eight patients were enrolled in the study. A final diagnosis was obtained in 24 patients (86 %). One patient (3 %) died before a diagnosis was obtained, while 3 were lost to follow-up (11 %). In 18/24 patients (74 %) the diagnosis was malignant. The mean sensitivity, specificity, and accuracy for the nCLE parameters ranged from 19 - 93 %, 0 - 56 %, 26 - 69 %, respectively. The inter-observer values ranged from κ = 0.20 - 0.41 for novices and κ = -0.02 - 0.38 for experts.

CONCLUSIONS

 The diagnostic value of nCLE in solid pancreatic masses is questionable and the inter-observer agreement for both novices and CLE experts appears limited.

A prospective study of endoscopic ultrasonography features, cyst fluid carcinoembryonic antigen, and fluid cytology for the differentiation of small pancreatic cystic neoplasms

Background and Objectives

With improvements in imaging technologies, pancreatic cystic lesions (PCLs) have been increasingly identified in recent years. However, the imaging modalities used to differentiate the categories of pancreatic cysts remain limited, which may cause confusion when planning treatment. Due to progress in endoscopic ultrasonography-guided fine-needle aspiration (EUS-FNA) technology, auxiliary diagnosis by the detection of cystic fluid has become a recent trend.

Methods

From March 2015 to April 2016, 120 patients with PCLs were enrolled in this study. According to the results of EUS, cyst fluid carcinoembryonic antigen (CEA) analysis, and cystic fluid cytology, the patients were divided into two groups: a nonmucinous and a mucinous group. Of those, 61 patients who had undergone surgical resection were included in the analysis. The clinical features, biochemical and tumor markers of cyst fluid as well as the cytological test results of the patients were compared with histopathology results.

Results

A cyst size of 4.0 cm was used as the boundary value; a cyst ≤4.0 cm was defined as a small PCL. 87 (72.5%) lesions were ≤4.0 cm, and 33 (27.5%) lesions were >4.0 cm. Regarding the analysis of CEA and carbohydrate antigens 19-9 (CA19-9), significant differences were found between the nonmucinous and mucinous groups (P < 0.05) according to nonparametric independent samples tests. The EUS, cystic fluid CEA, and cystic fluid cytology results were compared with the tissue pathology findings using McNemar's test (P < 0.05) and showed a sensitivity of 90% and a specificity of 84%.

Conclusion

A diagnostic combination of EUS, cyst fluid CEA, and cystic fluid cytology could be used to differentiate small pancreatic cystic neoplasms. Cystic fluid cytology analysis is helpful for planning treatment for pancreatic cystic tumors that pose a surgical risk.

Needle-based confocal laser endomicroscopy for the diagnosis of pancreatic cystic lesions: an international external interobserver and intraobserver study (with videos)

BACKGROUND AND AIMS

EUS-guided needle-based confocal laser endomicroscopy (nCLE) characteristics of common types of pancreatic cystic lesions (PCLs) have been identified; however, surgical histopathology was available in a minority of cases. We sought to assess the performance characteristics of EUS nCLE for differentiating mucinous from non-mucinous PCLs in a larger series of patients with a definitive diagnosis.

METHODS

Six endosonographers (nCLE experience >30 cases each) blinded to all clinical data, reviewed nCLE images of PCLs from 29 patients with surgical (n = 23) or clinical (n = 6) correlation. After 2 weeks, the assessors reviewed the same images in a different sequence. A tutorial on available and novel nCLE image patterns was provided before each review. The performance characteristics of nCLE and the κ statistic for interobserver agreement (IOA, 95% confidence interval [CI]), and intraobserver reliability (IOR, mean ± standard deviation [SD]) for identification of nCLE image patterns were calculated. Landis and Koch interpretation of κ values was used.

RESULTS

A total of 29 (16 mucinous PCLs, 13 non-mucinous PCLs) nCLE patient videos were reviewed. The overall sensitivity, specificity, and accuracy for the diagnosis of mucinous PCLs were 95%, 94%, and 95%, respectively. The IOA and IOR (mean ± SD) were κ = 0.81 (almost perfect); 95% CI, 0.71-0.90; and κ = 0.86 ± 0.11 (almost perfect), respectively. The overall specificity, sensitivity, and accuracy for the diagnosis of serous cystadenomas (SCAs) were 99%, 98%, and 98%, respectively. The IOA and IOR (mean ± SD) for recognizing the characteristic image pattern of SCA were κ = 0.83 (almost perfect); 95% CI, 0.73-0.92; and κ = 0.85 ± 0.11 (almost perfect), respectively.

CONCLUSIONS

EUS-guided nCLE can provide virtual histology of PCLs with a high degree of accuracy and inter- and intraobserver agreement in differentiating mucinous versus non-mucinous PCLs. These preliminary results support larger multicenter studies to evaluate EUS nCLE. (Clinical trial registration number: NCT02516488.).

Endoscopic ultrasonography evaluation for pancreatic cysts: Necessity or overkill?

Incidental pancreatic cysts have become gradually more recognized in clinical practice as a result of increased use of transabdominal ultrasound, computed tomography (CT) and magnetic resonance imaging (MRI). These lesions consist of inflammatory cysts (pseudocysts) and pancreatic cystic neoplasms (PCN) which have been classified as benign, premalignant and malignant. The diagnosis and management strategy of incidentally discovered pancreatic cysts can be challenging as the majority of them are PCN and CT or MRI alone may not be sufficient to provide an accurate diagnosis. Endoscopic ultrasound (EUS)-guided fine-needle aspiration provides a method to obtain cyst fluid for analysis and the recently developed EUS-based technology including contrast-enhanced ultrasound, cystoscopy and needle-based confocal laser endomicroscopy allows endosonographers to gain additional useful information. The current data suggest that EUS evaluation of pancreatic cysts offers some benefits especially in cases of inconclusive CT or MRI.

Needle-Based Confocal Laser Endomicroscopy for Evaluation of Cystic Neoplasms of the Pancreas

BACKGROUND

The accurate diagnosis of cystic neoplasms of the pancreas (CNP) with current diagnostic methods is limited. Endoscopic ultrasound (EUS)-guided needle-based confocal laser endomicroscopy (nCLE) is a new technique which can obtain images from the cyst wall during EUS-fine needle aspiration (EUS-FNA). The aim of this study was to assess the safety, feasibility, and diagnostic value of nCLE for CNP.

METHODS

Patients who underwent EUS-FNA to evaluate a CNP larger than 2 cm were enrolled. The cyst was punctured with 19-G FNA needle preloaded with an nCLE probe. The images from different areas of the cyst wall were recorded. Using the final diagnosis defined by surgery or EUS-FNA cyst fluid analysis, the accuracy of the confocal images was defined.

RESULTS

The procedure and image acquisition was successful in 18 of the 20 patients. Predefined typical structures for mucinous cysts were visualized in 8 of 12 (66%) cysts but none of the non-mucinous cysts. The superficial vascular network which is a typical finding of serous cysts was observed in 2 of 3 patients. The sensitivity, specificity, and diagnostic accuracy of the findings of epithelial structures by nCLE were 66, 100, and 80%, respectively, for a mucinous cyst diagnosis. All patients tolerated the procedure well, and no adverse effects were determined.

CONCLUSION

nCLE was found to be safe and feasible with high technical success, in this pilot study. With an overall accuracy of 80%, it has the potential to contribute to the diagnosis of CNP with specific imaging.

Imaging of pancreatic cystic lesions with confocal laser endomicroscopy: an ex vivo pilot study

BACKGROUND

The differential diagnosis of pancreatic cystic lesions (PCLs) is an increasingly common clinical challenge. Confocal laser endomicroscopy (CLE) may differentiate PCLs by imaging of the cyst wall. However, clinical experience is still limited, and better image definition and characterization of the cyst wall in a spectrum of cysts are needed. This experimental study aimed to expose detailed imaging characteristics of PCLs by CLE.

METHODS

Patients who underwent surgery of a PCL were enrolled. During surgery, intravenous fluorescein (2.5 ml of 10%) was injected just prior to the ligation of blood vessels supplying the pancreas. The freshly excised specimens were transected along the long axis to fully expose the luminal surface. A Gastroflex-UHD CLE probe (pCLE) was used manually to acquire images directly from the surface of cyst wall. The specimen subsequently underwent cross-sectional histology. All recorded data were analyzed by two investigators for predefined and original image findings of PCLs.

RESULTS

Ten cases were recruited into the study. All patients underwent surgery because of a mucinous cyst with worrisome features or a symptomatic PCL. Imaging was successful in all patients and differently shaped papillary projections (PP) were visualized in eight patients. Pathological examination of those patients confirmed 6 cases with Intraductal Papillary Mucinous Neoplasm (IPMN) and 2 cases with Mucinous Cystic Neoplasm (MCN). In two patients with serous cystadenoma, typical vascular network was visualized in one patient, and microcystic structures in the other. Three of the IPMNs were malignant. The loss of papillary margin integrity and significant fragmentation together with irregularity was detected in malignant IPMNs by CLE.

CONCLUSIONS

Pancreatic cyst epithelial wall can be visualized successfully by pCLE in ex vivo surgical specimens. Different papillary projections have been seen in all cases of IPMNs and MCNs. CLE has potential for identifying IPMN subtypes and for grading dysplasia.

Can endoscopic ultrasound-guided needle-based confocal laser endomicroscopy replace fine-needle aspiration for pancreatic and mediastinal diseases?

New applications of confocal laser endomicroscopy (CLE) have been developed, such as needle-based CLE (nCLE) for pancreatic masses, pancreatic cystic tumors, and lymph nodes. nCLE is feasible during endoscopic ultrasound (EUS) examination, and preliminary results are very encouraging and suggest this technology may be used in future as a useful adjunct in cases of inconclusive EUS-guided fine-needle aspiration. The aim of this paper is to give an update in this new technology and to define its place in the diagnosis of pancreatic masses and mediastinal diseases.

Validation of diagnostic characteristics of needle based confocal laser endomicroscopy in differentiation of pancreatic cystic lesions

Background and aims: Endoscopic ultrasound (EUS)-guided needle-based Confocal Laser Endomicroscopy (nCLE) characteristics of pancreatic cystic lesions (PCLs) have been identified in studies where the gold standard surgical histopathology was available in a minority of patients. There are diverging reports of interobserver agreement (IOA) and paucity of intraobserver reliability (IOR). Thus, we sought to validate current EUS-nCLE criteria of PCLs in a larger consecutive series of surgical patients. Methods: A retrospective analysis of patients who underwent EUS-nCLE at a single center was performed. For calculation of IOA (Fleiss' kappa) and IOR (Cohen's kappa), blinded nCLE-naïve observers (n = 6) reviewed nCLE videos of PCLs in two phases separated by a 2-week washout period. Results: EUS-nCLE was performed in 49 subjects, and a definitive diagnosis was available in 26 patients. The overall sensitivity, specificity, and accuracy for diagnosing a mucinous PCL were 94 %, 82 %, and 89 %, respectively. The IOA for differentiating mucinous vs. non-mucinous PCL was "substantial" (κ = 0.67, 95 %CI 0.57, 0.77). The mean (± standard deviation) IOR was "substantial" (κ = 0.78 ± 0.13) for diagnosing mucinous PCLs. Both the IOAs and mean IORs were "substantial" for detection of known nCLE image patterns of papillae/epithelial bands of mucinous PCLs (IOA κ = 0.63; IOR κ = 0.76 ± 0.11), bright particles on a dark background of pseudocysts (IOA κ = 0.71; IOR κ = 0.78 ± 0.12), and fern-pattern or superficial vascular network of serous cystadenomas (IOA κ = 0.62; IOR κ = 0.68 ± 0.20). Three (6.1 % of 49) patients developed post-fine needle aspiration (FNA) pancreatitis. Conclusion: Characteristic EUS-nCLE patterns can be consistently identified and improve the diagnostic accuracy of PCLs. These results support further investigations to optimize EUS-nCLE while minimizing adverse events.

STUDY REGISTRATION

NCT02516488.