Endoscopic management of Barrett esophagus

Activatable molecular probes for fluorescence-guided surgery, endoscopy and tissue biopsy

The real-time, dynamic optical visualization of lesions and margins ensures not only complete resection of the malignant tissues but also better preservation of the vital organs/tissues during surgical procedures. Most imaging probes with an "always-on" signal encounter high background noise due to their non-specific accumulation in normal tissues. By contrast, activatable molecular probes only "turn on" their signals upon reaction with the targeted biomolecules that are overexpressed in malignant cells, offering high target-to-background ratios with high specificity and sensitivity. This review summarizes the recent progress of activatable molecular probes in surgical imaging and diagnosis. The design principle and mechanism of activatable molecular probes are discussed, followed by specific emphasis on applications ranging from fluorescence-guided surgery to endoscopy and tissue biopsy. Finally, potential challenges and perspectives in the field of activatable molecular probe-enabled surgical imaging are discussed.

Super-achromatic optical coherence tomography capsule for ultrahigh-resolution imaging of esophagus

Endoscopic optical coherence tomography (OCT) is a noninvasive technology allowing for imaging of tissue microanatomies of luminal organs in real time. Conventional endoscopic OCT operates at 1300 nm wavelength region with a suboptimal axial resolution limited to 8-20 μm. In this paper, we present the first ultrahigh-resolution tethered OCT capsule operating at 800 nm and offering about 3- to 4-fold improvement of axial resolution (plus enhanced imaging contrast). The capsule uses diffractive optics to manage chromatic aberration over a full ~200 nm spectral bandwidth centering around 830 nm, enabling to achieve super-achromaticity and an axial resolution of ~2.6 μm in air. The performance of the OCT capsule is demonstrated by volumetric imaging of swine esophagus ex vivo and sheep esophagus in vivo, where fine anatomic structures including the sub-epithelial layers are clearly identified. The ultrahigh resolution and excellent imaging contrast at 800 nm of the tethered capsule suggest the potential of the technology as an enabling tool for surveillance of early esophageal diseases on awake patients without the need for sedation.

Developments in optical imaging for gastrointestinal surgery

To improve outcomes for patients with cancer, in terms of both survival and a reduction in the morbidity and mortality that results from surgical resection and treatment, there are two main areas that require improvement. Accurate early diagnosis of the cancer, at a stage where curative and, ideally, minimally invasive treatment is achievable, is desired as well as identification of tumor margins, lymphatic and distant disease, enabling complete, but not unnecessarily extensive, resection. Optical imaging is making progress in achieving these aims. This review discusses the principles of optical imaging, focusing on fluorescence and spectroscopy, and the current research that is underway in GI tract carcinomas.

Diagnosis and Surveillance of Barrett's Esophagus: Addressing the Transatlantic Divide

BACKGROUND

Barrett's esophagus is a premalignant condition of the esophagus leading to esophageal adenocarcinoma. No consensus exists between the UK and USA concerning the diagnosis of Barrett's esophagus. Although the diagnostic procedure is common, the required findings and diagnostic criteria vary. Both guidelines require endoscopy showing columnar epithelia lining the esophagus, but the US guidelines require the additional finding of intestinal metaplasia on biopsy to confirm diagnosis. Achievement of a consensus is of particular importance due to the established progression from Barrett's esophagus to esophageal adenocarcinoma. Of further importance is the increasing incidence of esophageal adenocarcinoma, a condition with poor overall survival, leading to various opinions on the utility of surveillance in patients.

DISCUSSION

A review of the vast array of literature revealed that substantial evidence exists in favor of both diagnostic criteria; hence, there is no easy way to identify the "correct" method of diagnosing Barrett's esophagus. USA recommends surveillance of Barrett's esophagus, whereas UK does not advocate it unless dysplasia is present. Surveillance was found to be effective, but this varied as did cost-effectiveness. Further research into diagnostic methods for Barrett's esophagus is needed to address areas of limited understanding, such that agreement can be reached and practice standardized. Surveillance was generally advocated, but with different criteria and time intervals, and new methods are being evaluated.

Comparison of endoscopic treatment modalities for Barrett's neoplasia

BACKGROUND

There are few data comparing endoscopic treatment outcomes for Barrett's esophagus (BE).

OBJECTIVE

To compare treatment outcomes in BE patients treated with radiofrequency ablation (RFA), RFA after EMR, and porfimer sodium photodynamic therapy (Ps-PDT).

DESIGN

Retrospective, observational study.

SETTING

Single tertiary center between 2001 and 2013.

PATIENTS

A total of 342 BE patients treated with RFA (n = 119), EMR+RFA (n = 98), and Ps-PDT (n = 125).

MAIN OUTCOME MEASUREMENTS

Rates of complete remission of intestinal metaplasia (CRIM), BE recurrence, and adverse events.

RESULTS

Baseline BE high-grade dysplasia (HGD) and adenocarcinoma were more common in the Ps-PDT group (89%) compared with the EMR-RFA (70%) and RFA (37%) groups. At a median follow-up of 14.2 months, 173 patients (50.6%) achieved CRIM. CRIM was significantly more common in Ps-PDT patients compared with RFA (P < .001) and EMR-RFA (P < .001) patients on multivariable analysis. In patients who achieved CRIM, the rates of subsequent BE recurrence were relatively similar among the 3 groups. Although the rates of bleeding were similar, strictures were less common in RFA patients (2.4%) compared with EMR-RFA (13.3%, P = .001) and Ps-PDT (10.4%, P =.043) patients.

CONCLUSION

This study of endoscopic treatment for Barrett's dysplasia and neoplasia found that complete remission was achieved more often and more rapidly after Ps-PDT with similar disease recurrence rates compared with EMR or RFA. Adverse events were more common after EMR and Ps-PDT. Further studies are required to determine which ablation and resection techniques are ideally suited for each BE patient.

The future developments in endoscopy

Gastrointestinal endoscopy has seen great changes over recent years, and the future seems bright. Looking forward, some advances in technology can be predicted, but the current financial climate may limit their widespread adoption. Increasing subspecialisation with continuing service development and quality assurance are likely to form the basis of the major changes over the next 5 years. Increasing juxtaposition between laparoscopic and endoscopic procedures presents the most exciting opportunities over the 10-year timeframe. This article extrapolates current trends to try to predict the different possibilities for endoscopy over the next decade.

Endoscopic therapies for Barrett's-associated dysplasia: a new paradigm for a new decade

The emergence of endoscopic therapies for Barrett's esophagus (BE)-associated dysplasia has significantly altered the management of this complex disease. Over the past decade, there has been a paradigm shift from that of pure surveillance to a more therapeutic approach in eradicating dysplastic BE. This strategy includes less invasive options than esophagectomy for high-grade dysplasia and early eradication of confirmed low-grade dysplasia. Although multiple modalities exist for endoscopic therapy, endoscopic mucosal resection coupled with radiofrequency ablation appears to be the most effective therapy, with minimal complications. Recent advances in endoscopic eradication therapies for dysplastic BE have fueled excitement for a significant weapon against the rising incidence of esophageal cancer.