The new kid on the block for advanced imaging in Barrett's esophagus: a review of volumetric laser endomicroscopy

Challenges in early detection and endoscopic resection of esophageal cancer: There is a long way to go

The publication by Qu et al provided a comprehensive discussion about the epidemiology, etiology, histopathology, early detection, and endoscopic treatment of esophageal carcinoma (EC) and summarized the progress in the advanced technologies for screening and endoscopic resection for EC. In this editorial, we will provide deeper insight into the challenges that hinder practical application of these advanced technologies along with the role of these technologies in upper endoscopy quality. More efforts need to be made to overcome the challenges and add the value of these technologies in upper endoscopy quality. Clinical outcomes of management strategies after noncurative endoscopic dissection for early EC patients need further investigation. The experiences with noncurative endoscopic resection of other organs may have certain implications for noncurative resection of early EC.

Are we Missing Barrett's Esophagus in Our Busy Endoscopy Practice? Improving Detection

Barrett's esophagus (BE) denotes the replacement of stratified squamous epithelium of esophagus by columnar epithelium. It is associated with a significantly increased risk of esophageal adenocarcinoma and hence patients with BE are advised endoscopic surveillance for early detection of dysplastic and neoplastic lesions. Esophageal cancer is the sixth most common cancer in terms of incidence and mortality in India. Around 15 to 25% of esophageal cancers are adenocarcinoma. BE is likely to be an important precursor of esophageal adenocarcinoma and we may be missing patients with BE in our busy endoscopy practice. The detection of BE may be improved by identifying high-risk groups, performing thorough endoscopic examination, and applying newer imaging techniques. The high-risk group includes patients with chronic gastroesophageal reflux disease, obesity, smoking, etc. During endoscopic examination, a careful assessment of the gastroesophageal junction and identification of important landmarks such as gastroesophageal junction and Z line are essential to detect BE. Management of BE depends on the detection of dysplasia and for this four quadrant mucosal biopsy is recommended every 1 to 2 cm. However, random biopsy samples only a small area of mucosa and advanced technologies for real-time detection of dysplasia and neoplasia may overcome this limitation. In this review, we discuss the current scenario of BE in India and ways to improve the detection of BE including dysplastic lesions.

Diagnostic performance of volumetric laser endomicroscopy for Barrett's esophagus dysplasia amongst gastroenterology trainees

BACKGROUND

Volumetric laser endomicroscopy (VLE) is an advanced imaging modality used in Barrett's esophagus (BE) surveillance. VLE image interpretation is challenged by subtle grayscale image variation across a large amount of data. Training in VLE interpretation is not standardized. This study aims to determine if VLE training can be incorporated into a gastroenterology (GI) fellowship curriculum with the use of a self-directed module.

METHODS

A standardized, self-directed training module (30 min) was created explaining the background and established VLE criteria for the diagnosis of BE dysplasia. A VLE image dataset was generated from a multicenter VLE database of targeted biopsies. GI trainees were asked to grade each image for the presence or absence of the following criteria (I) increased surface optical frequency domain imaging (OFDI) signal intensity and (II) atypical glands and provide a final diagnosis (dysplastic vs. non-dysplastic). Diagnostic performance was calculated and results compared to VLE expert interpretation using histology as the gold-standard.

RESULTS

The dataset included 50 VLE images (10 high-grade dysplasia, 40 non-dysplastic BE). VLE images were reviewed in a randomized and blinded fashion by 5 GI trainees with no prior VLE experience and 5 experienced VLE users. Sensitivity, specificity and accuracy of GI trainees was 83.3% (95% CI: 71.5-91.7%), 59.0% (95% CI: 51.6-66.0%), and 64.8% (95% CI: 58.5-70.7%) compared to 80.0% (95% CI: 67.7-89.2%), 79.5% (95% CI: 73.0-85.0%), and 79.6% (95% CI: 74.1-84.4%) for VLE experts respectively. The difference in specificity and accuracy between the two groups were statistically significant with P<0.001.

CONCLUSIONS

A brief training session on VLE is inadequate to reach competency in interpretation of VLE by GI trainees. Additional experience is required to accurately interpret VLE images.

Volumetric laser endomicroscopy features of dysplasia at the gastric cardia in Barrett's oesophagus: results from an observational cohort study

Objective

Volumetric laser endomicroscopy (VLE) is an advanced imaging modality used in Barrett’s oesophagus (BE) to help identify dysplasia in the oesophagus. VLE criteria exist for oesophageal dysplasia but not for dysplasia in the gastric cardia. The aim of this study was to determine if there are in vivo VLE features that can predict gastric cardia dysplasia in BE.

Design

This was a single-centre observational cohort study from August 2016 to August 2018. Patients were included if they had BE, were undergoing a VLE exam as standard of care, and had a suspicious target laser marked at the gastric cardia. The following VLE features were correlated to histology to determine if an association existed between histology subtype and VLE feature: wide crypts, irregular surface, one large isolated gland, multiple glands, and complex glands.

Results

A total of 110 in vivo gastric cardia targets in 77 patients with BE were analysed. The following abnormalities were identified: 61 wide crypts, 34 isolated glands, 16 irregular surfaces, 15 multiple glands, and 11 complex glands. Complex glands were the only VLE feature that correlated to any histology subtype. They were present in 71% of targets with high-grade dysplasia (HGD), T1a cancer or T1b cancer and had a sensitivity, specificity, and accuracy of 71%, 99%, and 85%, respectively. Of the 10 patients with complex glands on VLE and HGD/cancer on histology, 4 had a normal-appearing mucosa (40%) on endoscopy.

Conclusion

Identification of complex glands on VLE may aid in detection of HGD or early cancer in the gastric cardia in BE. This is particularly important, as dysplasia at the gastric cardia can be difficult to see endoscopically.

Advances in the diagnosis and surveillance of Barrett's esophagus (with videos)

BACKGROUND AND AIMS

Most patients diagnosed with esophageal adenocarcinoma do not carry a known diagnosis of Barrett's esophagus (BE), suggesting that an improved approach to screening may potentially be of benefit. The use of dysplasia as a biomarker and random biopsy protocols for its detection has limitations. In addition, detecting and appropriately classifying dysplasia in patients with known BE can be difficult.

METHODS

This document reviews several technologies with a recently established or potential role in the diagnosis and/or surveillance of BE as well as risk stratification for progression to esophageal adenocarcinoma.

RESULTS

Two technologies were reviewed for imaging or tissue sampling: (1) wide-area transepithelial sampling and (2) volumetric laser endomicroscopy. Four technologies were reviewed for molecular and biomarker technologies for diagnosis and risk stratification: (1) Cytosponge, (2) mutational load, (3) fluorescence in situ hybridization, and (4) immunohistochemistry.

CONCLUSION

Several technologies discussed in this document may improve dysplasia detection in BE in a wide-field manner. Moreover, the addition of different biomarkers may aid in enhanced risk stratification to optimize approaches to surveillance or treatment for patients with BE.

A roadmap for the clinical implementation of optical-imaging biomarkers

Clinical workflows for the non-invasive detection and characterization of disease states could benefit from optical-imaging biomarkers. In this Perspective, we discuss opportunities and challenges towards the clinical implementation of optical-imaging biomarkers for the early detection of cancer by analysing two case studies: the assessment of skin lesions in primary care, and the surveillance of patients with Barrett's oesophagus in specialist care. We stress the importance of technical and biological validations and clinical-utility assessments, and the need to address implementation bottlenecks. In addition, we define a translational roadmap for the widespread clinical implementation of optical-imaging technologies.

Incremental yield of dysplasia detection in Barrett's esophagus using volumetric laser endomicroscopy with and without laser marking compared with a standardized random biopsy protocol

BACKGROUND AND AIMS

Volumetric laser endomicroscopy (VLE) is a new wide-field advanced imaging technology for Barrett's esophagus (BE). No data exist on incremental yield of dysplasia detection. Our aim is to report the incremental yield of dysplasia detection in BE using VLE.

METHODS

This is a retrospective study from a prospectively maintained database from 2011 to 2017 comparing the dysplasia yield of 4 different surveillance strategies in an academic BE tertiary care referral center. The groups were (1) random biopsies (RB), (2) Seattle protocol random biopsies (SP), (3) VLE without laser marking (VLE), and (4) VLE with laser marking (VLEL).

RESULTS

A total of 448 consecutive patients (79 RB, 95 SP, 168 VLE, and 106 VLEL) met the inclusion criteria. After adjusting for visible lesions, the total dysplasia yield was 5.7%, 19.6%, 24.8%, and 33.7%, respectively. When compared with just the SP group, the VLEL group had statistically higher rates of overall dysplasia yield (19.6% vs 33.7%, P = .03; odds ratio, 2.1, P = .03). Both the VLEL and VLE groups had statistically significant differences in neoplasia (high-grade dysplasia and intramucosal cancer) detection compared with the SP group (14% vs 1%, P = .001 and 11% vs 1%, P = .003).

CONCLUSION

A surveillance strategy involving VLEL led to a statistically significant higher yield of dysplasia and neoplasia detection compared with a standard random biopsy protocol. These results support the use of VLEL for surveillance in BE in academic centers.

Identification of volumetric laser endomicroscopy features of colon polyps with histologic correlation

BACKGROUND AND AIMS

There are limited data on the use of volumetric laser endomicroscopy (VLE) for imaging colon polyps. Our aim was to identify VLE features of colon polyps.

METHODS

A total of 45 patients were included; 43 underwent endoscopic mucosal resection of colorectal polyps 2 cm or greater. These polyps were then scanned with VLE immediately after resection. Two patients who underwent partial colonic resection served as controls.

RESULTS

Forty-three polyps were included with review of matching histology: 3 intramucosal cancer (IMCA), 5 tubular adenoma (TAs)/tubulovillous adenoma (TVA) with high-grade dysplasia (HGD), 9 TVA with only low-grade dysplasia (LGD), 5 serrated adenoma, and 21 TA with LGD. All TAs and TVAs were hyper-reflective compared with normal tissue. Effacement occurred in 82.4% (14/17) of the colonic polyps with advanced pathology (TVA with HGD/IMCA) compared with 11.6% (3/26) with non-advanced pathology (TA with LGD and serrated adenoma) (P < .0001). Forty-seven percent (8/17) of polyps with advanced pathology had greater than 5 glands on VLE compared with none in the non-advanced pathology group (P = .0001). An irregular surface mainly occurred in polyps with high-grade pathology (HGD/IMCA) versus TAs. Eighty-eight percent of polyps with HGD/IMC had an irregular surface (7/8) versus 6% (2/35) of TAs (P < .0001).

CONCLUSIONS

In this ex vivo clinicopathologic study, we show that there are distinct VLE features of colon polyps that may help identify polyps or features of a higher-grade lesion. This may have implications for possible in vivo application to aid in dysplasia or polyp detection.

Emerging optical methods for endoscopic surveillance of Barrett's oesophagus

Barrett's oesophagus is an acquired metaplastic condition that predisposes patients to the development of oesophageal adenocarcinoma, prompting the use of surveillance regimes to detect early malignancy for endoscopic therapy with curative intent. The currently accepted surveillance regime uses white light endoscopy together with random biopsies, but has poor sensitivity and discards information from numerous light-tissue interactions that could be exploited to probe structural, functional, and molecular changes in the tissue. Advanced optical methods are now emerging that are highly sensitive to these changes and hold potential to improve surveillance of Barrett's oesophagus if they can be applied endoscopically. The next decade will see some of these exciting new methods applied to surveillance of Barrett's oesophagus in new device architectures for the first time, potentially leading to a long-awaited improvement in the standard of care.

Future of diagnosing neoplasia in Barrett's esophagus: volumetric laser endomicroscopy

Esophageal adenocarcinoma (EAC) is one of the deadliest carcinoma faced by gastroenterologists. Any insult to esophagus that causes replacement of normal squamous epithelium with columnar intestinal epithelium is labelled as the initiating event of the metaplasia-neoplasia sequence. Barrett's esophagus is the precursor to EAC. Currently, endoscopically obtained biopsies are used to detect neoplastic changes in patients with Barrett's esophagus (BE); however, it is not cost effective and hence a better screening modality is needed. Volumetric laser endomicroscopy (VLE) has been under study for the past few years and has shown promising results to overcome the shortcoming faced in the biopsy samplings. It is a second-generation optical coherence tomography (OCT) that provides high-resolution cross-sectional imaging of the esophageal mucosa using near-infrared light. The principle is similar to endosonography, but image formation in OCT depends on variations in the reflection of light from different tissue layers rather than ultrasonic waves.

Use of volumetric laser endomicroscopy for determining candidates for endoscopic therapy in superficial esophageal squamous cell carcinoma

Background

Accurate staging of superficial esophageal squamous cell cancer (ESCC) for endoscopic therapy is challenging. Optical coherence tomography (OCT) has been shown to be superior to high-resolution endoscopic ultrasound (EUS). Volumetric Laser Endomicroscopy (VLE), a second-generation OCT, has recently become commercially available.

Objective

To assess if VLE can determine which patients with superficial ESSC can undergo endoscopic therapy.

Methods

This is a multi-center retrospective study. Patients were included if (a) they had visible ESCC, (b) they underwent VLE and EUS for staging, and c) if superficial disease was suspected then endoscopic resection had to be performed to have accurate histology to compare the VLE scan to. VLE scans were then compared to the gold standard: histology for superficial disease and EUS for disease T1b and greater.

Results

Seventeen patients were included with the following disease: squamous intraepithelial neoplasia (4 patients), T1a disease (6 patients), T1b (2 patients), T2 disease (2 patients) and T3 disease (3 patients). VLE was able to distinguish superficial disease, defined as disease limited up to the lamina propria, from non-superficial disease in all cases.

Conclusions

VLE may be able to determine which ESCC patients are candidates for endoscopic therapy. Prospective studies are needed to confirm this.

New Approaches to Gastroesophageal Reflux Disease

BACKGROUND

Gastroesophageal reflux disease (GERD) is the most common gastrointestinal disorder of the esophagus. It is a chronic, progressive disorder that presents most typically with heartburn and regurgitation and atypically with chest pain, dysphagia, chronic cough, globus, or sore throat. The mainstay for diagnosis and characterization of the disorder is esophagoduodenoscopy (EGD), high-resolution esophageal manometry, and symptom-associated ambulatory esophageal pH impedance monitoring. Additional studies that can be useful in certain clinical presentations include gastric scintigraphy and oral contrast upper gastrointestinal radiographic series.

DISCUSSION

Refractory GERD can be surgically managed with various techniques. In obese individuals, laparoscopic Roux-en-Y gastric bypass should be considered due to significant symptom improvement and lower incidence of recurrent symptoms with weight loss. Otherwise, laparoscopic Nissen fundoplication is the preferred surgical technique for treatment of this disease with concomitant hiatal hernia repair when present for either procedure. The short-term risks associated with these procedures include esophageal or gastric injury, pneumothorax, wound infection, and dysphagia. Emerging techniques for treatment of this disease include the Linx Reflux Management System, EndoStim LES Stimulation System, Esophyx® and MUSE™ endoscopic fundoplication devices, and the Stretta endoscopic ablation system. Outcomes after surgical management of refractory GERD are highly dependent on adherence to strict surgical indications and appropriate patient-specific procedure selection.

Past, present and future of Barrett's oesophagus

Barrett's oesophagus is a condition which predisposes towards development of oesophageal adenocarcinoma, a highly lethal tumour which has been increasing in incidence in the Western world over the past three decades. There have been tremendous advances in the field of Barrett's oesophagus, not only in diagnostic modalities, but also in therapeutic strategies available to treat this premalignant disease. In this review, we discuss the past, present and future of Barrett's oesophagus. We describe the historical and new evolving diagnostic criteria of Barrett's oesophagus, while also comparing and contrasting the British Society of Gastroenterology guidelines, American College of Gastroenterology guidelines and International Benign Barrett's and CAncer Taskforce (BOBCAT) for Barrett's oesophagus. Advances in endoscopic modalities such as confocal and volumetric laser endomicroscopy, and a non-endoscopic sampling device, the Cytosponge, are described which could aid in identification of Barrett's oesophagus. With regards to therapy we review the evidence for the utility of endoscopic mucosal resection and radiofrequency ablation when coupled with better characterization of dysplasia. These endoscopic advances have transformed the management of Barrett's oesophagus from a primarily surgical disease into an endoscopically managed condition.

Volumetric laser endomicroscopy in the management of Barrett's esophagus

PURPOSE OF REVIEW

The incidence of esophageal adenocarcinoma is on the rise despite widespread appreciation that the precursor lesion is Barrett's esophagus. Studies have shown that some patients known to have Barrett's esophagus develop cancer despite their enrollment in conventional endoscopic surveillance programs. This highlights the need for advanced endoscopic imaging to help identify early neoplasia and prevent its progression to esophageal cancer. Recently, a wide-field, second-generation optical coherence tomography endoscopic platform called volumetric laser endomicroscopy (VLE) was cleared by the Food and Drug Administration and made commercially available for advanced imaging in Barrett's esophagus.

RECENT FINDINGS

The current review discusses current literature on VLE imaging in Barrett's esophagus. Based on ex-vivo studies, criteria have been established for identifying Barrett's esophagus-associated neoplasia. In addition, recent studies, case series, and case reports have demonstrated that VLE is well tolerated, efficacious, and can target neoplasia.

SUMMARY

VLE is a new advanced imaging platform for Barrett's esophagus with considerable promise to target Barrett's esophagus-associated neoplasia. The following are needed to establish VLE's clinical role: studies showing incremental yield of dysplasia detection using VLE, studies to determine VLE's in-vivo diagnostic accuracy for identifying and classifying Barrett's esophagus-associated neoplasia, and studies on the cost-efficacy of VLE.

Volumetric laser endomicroscopy in Barrett's esophagus: interobserver agreement for interpretation of Barrett's esophagus and associated neoplasia among high-frequency users

BACKGROUND AND AIMS

Targeting neoplasia in Barrett's esophagus (BE) is challenging. Volumetric laser endomicroscopy (VLE) is a new imaging technique that allows for real time cross-sectional microstructure imaging that can detect BE neoplasia. The interobserver agreement among users in practice is unknown.

METHODS

Eight high-volume users of VLE from different academic centers in the United States evaluated 120 stored VLE images blinded to the endoscopic and clinical findings. There were 30 images for each tissue type: gastric cardia, esophageal squamous mucosa, nonneoplastic BE, and neoplastic BE. Each image with BE had corresponding histology confirming the tissue diagnosis. Each normal esophagus and gastric cardia had matching endoscopic images confirming normal mucosa. These were considered the criterion standard. Respondents were asked to classify the images into 1 of each category. Agreement among the users was measured.

RESULTS

The overall agreement among users was almost perfect (kappa = 0.81; 95% confidence interval [CI], 0.79-0.83). For esophageal squamous and gastric cardia, the agreement was almost perfect (kappa 0.95 and 0.86, respectively [95% CI, 0.92-0.98 and 0.83-0.89]). For nonneoplastic BE and neoplastic BE, the agreement was strong (kappa 0.66 [95% CI, 0.63-0.69] and 0.79 [95% CI, 0.75-0.82], respectively). When compared with the criterion standard, the median accuracy for identifying normal squamous mucosa, normal gastric mucosa, nonneoplastic BE, neoplastic BE, and all tissue types was 99% (95% CI, 98%-100%), 97% (95% CI, 95%-99%), 93% (95% CI, 88%-98%), 95% (95% CI, 91%-99%), and 96% (95% CI, 94%-99%), respectively.

CONCLUSIONS

VLE has a high level of agreement and accuracy among high-volume users.

The Role of Adjunct Imaging in Endoscopic Detection of Dysplasia in Barrett's Esophagus

Advances in imaging technologies have demonstrated promise in early detection of dysplasia and cancer in Barrett's esophagus (BE). Optical chromoendoscopy, dye-based chromoendoscopy, and novel technologies have provided the opportunity to visualize the cellular and subcellular structures. Only narrow-band imaging and acetic acid chromoendoscopy have reached benchmarks for clinical use. Volumetric laser endomicroscopy and molecular imaging are not established for routine use. Best practice in management of BE should be focused on careful endoscopic examination, resection, or ablation of the entire abnormal lesion, as well as the use of available imaging technique that has good diagnostic accuracy.

Evaluation of NinePoint Medical's Nvision VLE device for gastrointestinal applications

INTRODUCTION

The incidence of esophageal adenocarcinoma (EAC) has increased over the last few decades. With a known precursor lesion, Barrett's esophagus, this remains a target for screening and surveillance with the goal of detecting and providing curative treatment for early neoplasia. Areas covered: Current surveillance techniques rely on white light endoscopy and random tissue sampling which is time consuming, costly and prone to sampling error. Volumetric laser endomicroscopy (VLE), a second-generation optical coherence technology, has emerged as an advanced imaging modality with the potential to improve dysplasia detection, surveillance and subsequently prevent esophageal adenocarcinoma. This review will focus on the use of VLE for advanced imaging of Barrett's esophagus and summarize its current and potential uses elsewhere in the GI tract. Expert commentary: NinePoint's VLE imaging device enables imaging of large segments of BE facilitating identification of luminal and subsurface abnormalities that may have otherwise been missed. Its diagnostic accuracy is improving and laser-marking system adds the capacity for accurate VLE-histologic correlation. With the adoption of dysplasia scoring systems that utilize very few VLE imaging features, inexperienced endoscopists will likely be able to pick out areas concerning for dysplasia to target therapy.

The ecosystem that powered the translation of OCT from fundamental research to clinical and commercial impact [Invited]

25 years is a relatively short period of time for a medical technology to become a standard of care impacting the treatment of millions of people every year. Yet 25 years ago there were no OCT companies, no OCT products, no OCT markets, and only one journal article published using the term OCT (optical coherence tomography). OCT has had a tremendous scientific, clinical, and economic impact on society. Today, it is estimated that there are ~30 Million OCT imaging procedures performed worldwide every year and the OCT system market is approaching $1B per year. OCT has helped diagnose patients with retinal disease at early treatable stages, preventing or greatly reducing irreversible vision loss. The technology has facilitated pharmaceutical development and contributed to fundamental understanding of disease mechanisms in multiple fields. The invention and translation of OCT from fundamental research to daily clinical practice would not have been possible without a complex ecosystem involving interaction among physics, engineering, and clinical medicine; government funding of fundamental and clinical research; collaborative and competitive research in the academic sector; entrepreneurship and industry; addressing real clinical needs; harnessing the innovation that occurs at the boundaries of disciplines; and economic and societal impact. This invited review paper discusses the translation of OCT from fundamental research to clinical practice and commercial impact, as well as describes the ecosystem that helped power OCT to where it is today and will continue to drive future advances. While OCT is an example of a technology that has had a powerful impact, there are many biomedical technologies which are poised for translation to clinical practice, and it is our hope that highlighting this ecosystem will help accelerate their translation and clinical impact.

Advanced Imaging Techniques in Gastrointestinal Endoscopy

The fundamental approach to endoscopy is to identify concerning and potentially premalignant lesions in the gastrointestinal tract, sample or resect the area of interest, await histologic results, and subsequently formulate a treatment and/or surveillance strategy. Detecting subtle lesions and deciding whether they are clinically significant are challenges that rely on the endoscopist's observation skills and experience. Enhanced imaging technologies have been developed to aid in lesion identification and classification, enabling better visualization of the lumen from a wide-field view while also enabling real-time near-field, including cellular level, imaging of the tissue. These innovations can potentially help reduce the rate of missed lesions, the need for extensive surveillance biopsies, and the frequency of surveillance. Several of these advanced imaging technologies are discussed in this review.