Endoscopic imaging in Barrett’s esophagus

Abstract

Barrett’s esophagus is the only known precursor that predisposes patients to the development of esophageal adenocarcinoma. The current recommended surveillance method is targeted biopsies of any abnormalities followed by random four-quadrant biopsies every 2 cm using standard white light endoscopy. Compliance with this and sampling error are two of the biggest problems. Several novel imaging technologies have been developed to aid the diagnosis of early neoplasia in Barrett’s esophagus. There are emerging data that some of these new modalities can increase the yield of detecting dysplasia. This review will discuss some of the present available techniques and technologies including chromoendoscopy, narrow-band imaging, autofluorescence imaging, optical coherence tomography, confocal endomicroscopy and endocytoscopy. Based on the current evidence, these imaging modalities appear to be promising as adjunctive tools to white light endoscopy. A few of them, nevertheless, remain experimental due to expense, lack of expertise, generalizability as well as reproducibility of results.

Keywords:

• acetic acid
• autofluorescence imaging
• Barrett’s esophagus
• chromoendoscopy
• confocal endomicroscopy
• endocystoscopy
• indigo carmine
• methylene blue
• narrow-band imaging
• optical coherence tomography

Acknowledgements

The authors are thankful to Lyell McEwin Hospital, University of Adelaide for a library contribution of an article to aid in the preparation of this manuscript.

Financial & competing interests disclosure

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

No writing assistance was utilized in the production of this manuscript.

Key issues

• Despite being the most studied dye, methylene blue has been found in a meta-analysis to have no added value to random biopsy.

• Acetic acid is the preferable agent for chromoendoscopy as it is easily available and cost-effective. It has high diagnostic accuracy for both specialized intestinal metaplasia and early neoplasia and reduces the number of biopsy per patient for diagnosis.

• Narrow-band imaging (NBI) has higher sensitivity than high-definition white light endoscopy in detecting dysplastic lesions. With NBI, mucosal morphology can be studied through pit and microvasculature pattern recognition. Distorted pit and irregular microvasculature would be considered as high-risk lesions, as compared to round pit and regular microvasculature.

• Autofluorescence imaging uses the red–green–blue sequential illumination to form part of trimodal imaging video endoscopes. It is known to enhance lesion detection, but its diagnostic role is limited due to poor specificity.

• Optical coherence tomography is a light-based imaging modality that allows visualization of all three layers of the epithelium. It increases the detection rate of early neoplasia and buried glands. Several factors such as poor inter-observer agreement, lack of training and suboptimal image quality prevent its routine use in clinical practice.

• Confocal endomicroscopy provides narrow field visualization but high-resolution cross-sectional images of the mucosa. It has high sensitivity and specificity in detecting early neoplasia, but must be used with a wide field technology (white light endoscopy or NBI). Because of its high negative predictive value, patients can forego biopsy if shown to have no dysplasia.

• Endocytoscopy is an ultra-high magnification technique that enables in vivo surface morphology assessment with the potential to guide biopsy and histological diagnosis. Similar to confocal endomicroscopy, there are issues with image stabilization and adequacy of microscopic examination skills. Limited data exist with this technology.

• Although promising, ongoing trials and training are further required to assess the effectiveness of these novel imaging modalities. Diagnostic criteria need to be standardized to improve the reproducibility.