Poor agreement between endoscopists and gastrointestinal pathologists for the interpretation of probe-based confocal laser endomicroscopy findings

The Use of Confocal Laser Endomicroscopy in Diagnosing Barrett’s Esophagus and Esophageal Adenocarcinoma

Confocal laser endomicroscopy (CLE) is a diagnostic technique that enables real-time microscopic imaging during microscopic examination and evaluation of epithelial structures with 1000-fold magnification. CLE can be used in the diagnosis of various pathologies, in pneumology, and in urology, and it is very widely utilized in gastroenterology, most importantly in the diagnosis of Barrett’s esophagus (BE), esophageal adenocarcinoma (EAC), biliary strictures, and cystic pancreatic lesions. A literature search was made in MEDLINE/PubMed and Google Scholar databases while focusing on diagnostics using CLE of BE and EAC. We then examined randomized and observational studies, systematic reviews, and meta-analyses relating to the utilization of CLE in BE and EAC diagnostics. Here, we discuss whether CLE can be a suitable diagnostic method for surveillance of BE. Even though many studies have proven that CLE increases diagnostic accuracy in detecting neoplastic transformation of BE, CLE is still not used as a standard diagnostic tool in BE surveillance due to a deficiency of scientific evidence. More studies and data are needed if CLE is to find a place as a new technique in BE surveillance.

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.

Diagnostic Approach to Suspected Perihilar Malignancy

Background

Cholangiocarcinomas are relatively rare tumors most frequently arising from the epithelium of the hilar bile ducts. The diagnosis is often made in advanced (symptomatic) stages, which accounts for the infavorable prognosis with a 5-year survival of less than 10%. Identification of perihilar cholangiocarcinoma (pCCA) is often challenging because there is no single method offering sufficient diagnostic accuracy.

Summary

Most tumors arise in patients without specific risk factors. Clinical symptoms of pCCA are nonspecific and reliable biomarkers are lacking, with carbohydrate antigen 19-9 being the most commonly used tumor marker (but with a low accuracy). Cross-sectional imaging (CT and MRI) is used to identify and map hilar strictures and determine resectability by showing vascular involvement. Endoscopic ultrasound offers additional information on locoregional tumor spread and lymph node involvement. Endoscopic retrograde cholangiography in combination with cholangioscopy gives direct access to and imaging of hilar strictures but it does not always distinguish between pCCA and benign hilar strictures. Tissue acquisition for histological diagnosis is challenging, with frequent sampling errors regardless of the method of biopsy procurement because of the cellular paucity of tumor tissue.

Key Messages

In suspected perihilar malignancy, a mosaic of clinical data has to be taken into account. Histological evaluation of (endoscopically harvested) specimens is pivotal to differential diagnosis. Several new techniques to increase diagnostic accuracy are under investigation (biomarkers and genetic testing among others).

Quantitative Diagnosis of Atrophic Gastritis by Probe-Based Confocal Laser Endomicroscopy

Aims

The aims of this study were to characterize nonatrophic and atrophic gastric mucosa under conventional endoscopy and probe-based confocal laser endomicroscopy (pCLE) modes and to define quantitative diagnostic parameters for these lesions under pCLE.

Method

In phase I, 64 patients with gastric mucosal lesions diagnosed by gastrointestinal endoscopy were enrolled in the study. Normal mucosa and suspicious lesions were evaluated under normal white light imaging (WLI) and pCLE mode. Descriptive characteristic of gastric mucosal inflammation and atrophy under pCLE were defined according to the histology. In phase II, the criteria for nonatrophic gastritis (NAG) and chronic atrophic gastritis (CAG) under pCLE were used to diagnose the mucosal lesions in 431 patients. Diagnostic accuracy of each endoscopy modes was evaluated by measuring the concordance with histology.

Result

A total of 64 patients with 187 positions were enrolled in the first part of this study. According to the histological diagnosis, the vessel diameter was increased in the NAG (11.18 ± 0.1 μm) and CAG (13.21 ± 0.29 μm) and CAG (13.21 ± 0.29 μm) and CAG (13.21 ± 0.29 μm) and CAG (13.21 ± 0.29 μm) and CAG (13.21 ± 0.29 μm) and CAG (13.21 ± 0.29 μm) and CAG (13.21 ± 0.29 

Conclusion

pCLE shows high potential for the diagnosis of gastric inflammation and atrophy based on quantitative criteria and has the ability to be a substitute for histology in the diagnosis of diffuse lesions in the stomach.

Margin diagnosis for endoscopic submucosal dissection of early gastric cancer using multiphoton microscopy

BACKGROUND AND AIMS

Endoscopic submucosal dissection (ESD) has become the primary option for the treatment of early gastric cancer (EGC). Thus, it is necessary to diagnose whether residual cancer cells exist in the ESD specimen margins, which can affect tumor recurrence and survival rates in the future. Multiphoton microscopy (MPM) can be suitably used for nondestructive imaging of biological tissue on a cellular level to enable real-time guidance during endoscopic therapy. Considering this, the objective of this study is to explore the practicality of MPM for the diagnosis of ESD specimen margins in the case of EGC.

METHODS

First, a total of 20 surgical samples was imaged using the proposed MPM technique to obtain two-photo excited fluorescence signal from the intrinsic fluorescent substances within cells and second-harmonic generation signal from collagen; these signals were used to determine MPM pathological features for margin diagnosis. Then, a double-blind study of 50 samples was conducted to evaluate the diagnosis results based on the obtained MPM pathological features.

RESULTS

Multiphoton microscopy can accurately identify the cytological and morphological differences between tissue in the negative and positive margin. The sensitivity, specificity, accuracy, negative predictive, and positive predictive values of MPM in the diagnosis of ESD specimen margins were 97.62, 75.00, 94.00, 95.35, and 85.71%, respectively.

CONCLUSION

These results indicate that MPM can be used as an effective, real-time, and label-free novel method to determine intraoperative resection margins.

Validation of Probe-based Confocal Laser Endomicroscopy (pCLE) Criteria for Diagnosing Colon Polyp Histology

BACKGROUND

Validated probe-based confocal endomicroscopy (pCLE) criteria for distinguishing hyperplastic polyps (HPs) and tubular adenomas (TA) have not yet been developed.

AIM

To develop pCLE criteria for distinguishing HP from TA and evaluate its performance characteristics among experts.

METHODS

pCLE criteria for colon polyp histology were developed and tested in 2 phases prospectively. Phase I: 8 preliminary criteria were developed and tested internally. Criteria achieving an accuracy of >75% (epithelial surface: regular vs. irregular; goblet cells: increased vs. decreased; gland axis: horizontal vs. vertical; gland shape: slit/stellate vs. villiform; image scale: gray vs. dark) were evaluated in Phase II of study wherein external assessors evaluated these criteria in a separate set of pCLE videos. Accuracy and interobserver agreement (95% confidence intervals) were determined for colon histology prediction.

RESULTS

Phase I (criteria development/internal testing): 8 criteria were assessed by 4 pCLE experts using 28 videos (14 HP/14 TA). Five of 8 pCLE criteria met selection for phase II (accuracy >75%). Phase II (external validation): 36 pCLE colon polyp videos (HP 16/TA 20) were evaluated by 8 external assessors. Overall accuracy in diagnosis of colon polyp histology was 84.9% (95% confidence interval, 81.7-87.7). Of predictions made with high confidence (75%), histology was predicted with an accuracy of 91%, sensitivity 83%, specificity 100%, negative predictive value 87% and positive predictive value 98%. Interobserver agreement was substantial (κ=0.73).

CONCLUSIONS

We demonstrate the development and validation of pCLE criteria for prediction of colon polyp histology. Using these criteria, overall accuracy in differentiating TA from HP was high with substantial interobserver agreement.

Confocal Laser Endomicroscopy for Diagnosing Malignant Pleural Effusions

Background

Confocal laser endomicroscopy (CLE) enables “in vivo” microscopic tissue diagnosis based on tissue reflectance or tissue fluorescence upon application of fluorescence agents. The aim of the present study was to evaluate CLE as a new diagnostic approach for differentiation between malignant versus non-malignant pleural effusions.

Material/Methods

In 100 patients with pleural effusions, thoracentesis was performed. Cresyl violet and acriflavine were used as contrast agents for probe-based CLE of effusions. CLE video sequences were assessed by 4 independent investigators (2 experienced in this technique, 2 with only basic knowledge). In addition, all CLE samples were evaluated by an expert pathologist (p). Results were compared with conventional cytology of effusions and histology of cell blocks.

Results

CLE reliably permitted identification of malignant cells in pleural effusions. Sensitivity for detection of malignant effusions was 87% (p: 87%) and 81% (p: 72%) for acriflavine and cresyl violet, respectively. With regard to specificity, acriflavine and cresyl violet yielded a mean value of 99% (p: 100%) and 92% (p: 100%).

Conclusions

In this pilot study, CLE permitted simple and rapid detection of malignant pleural effusions. Larger prospective studies are warranted to corroborate our findings.

Emerging Technologies for the Diagnosis of Perihilar Cholangiocarcinoma

The diagnosis of malignant biliary strictures remains problematic, especially in the perihilar region and in primary sclerosing cholangitis (PSC). Conventional cytology obtained during endoscopic retrograde cholangiography (ERC)-guided brushings of biliary strictures is suboptimal due to limited sensitivity, albeit it remains the gold standard with a high specificity. Emerging technologies are being developed and validated to address this pressing unmet patient need. Such technologies include enhanced visualization of the biliary tree by cholangioscopy, intraductal ultrasound, and confocal laser endomicroscopy. Conventional cytology can be aided by employing complementary and advanced cytologic techniques such as fluorescent in situ hybridization (FISH), and this technique should be widely adapted. Interrogation of bile and serum by examining extracellular vesicle number and cargo, and exploiting next-generation sequencing and proteomic technologies, is also being explored. Examination of circulating cell-free deoxyribonucleic acid (cfDNA) for differentially methylated regions is a promising test which is being rigorously validated. The special expertise required for these analyses has to date hampered their validation and adaptation. Herein, we will review these emerging technologies to inform the reader of the progress made and encourage further studies, as well as adaptation of validated approaches.