Review for 10.1186/s12876-020-01534-2 (2020)

Reviewer’s report
Title: 
Narrow band imaging under less-air condition improves the visibility of
superficial esophageal squamous cell carcinoma
Version: 
0 
Date: 
11 May 2020
Reviewer's report:
In this manuscript, the authors report that less-air conditions can improve
visibility of flat ESCC lesions during NBI inspection of the esophagus. These
results can be potentially impactful since the diagnostic characteristics of many
advanced imaging modalities, including NBI, depend on not only the endoscopic
imaging performance, but also how it is used when put in hands of endoscopists
with varied levels of expertise. In the reviewer's opinion, the study proposes an
easy-to-use technique that can improve clinical visibility of flat esophageal
lesions, and it can be made stronger by addressing the following comments.
Major comments:
1. The reviewer's major comment is that the authors can better study the potential
contributing factors for improved visibility. To make the best use of the
technique, it is crucial for the endoscopists, especially novices, to better
understand the working principle. In the manuscript, the authors hypothesized
that the enhanced visibility may arise from either thickening of esophageal wall
or brighter images with a closer imaging distance. While it is challenging to
directly study the former, the latter seems to be supported by examples images in
Figure 1, showing that all images under less-air conditions reveal a closer view
of the lesions. These few examples suggest that the imaging working distance, as
well as the perspective, can be important in visualizing those flat lesions.
Therefore, in the reviewer's opinion, it is important to analyze and quantify the
images in terms of brightness, perspective and magnification, which is feasible
with the reported dataset. The reviewer believes this will provide insight on how
the reported technique can be most effectively used during clinical practice.
2. The authors reported less-air condition improved visibility, but the other
important question is whether the technique also contributed to improved
diagnostic yield. If not, the added value of suctioning air can be limited. For
example, are all lesions still distinguishable with the standard air condition, even
in cases where visibility is worse than less-air condition? Or did less-air
conditions allow for more accurate diagnosis of flat lesions?
3. The authors also mentioned that a soft black hood was used at the endoscope
tip. In addition, mild magnification was used in less-air conditions. Were those
associated with enhanced visibility? If so, could either of them play a role in
better visualization of flat lesions?
4. As the authors stated, image brightness in NBI can be linked to diagnostic
performance, which has also been reported in previous studies. In the current
study, since different endoscopes have been used, it is important to know
whether they all support second-generation (brighter) NBI. If not, the dataset can
be further stratified and analyzed.
Are the methods appropriate and well described?
If not, please specify what is required in your comments to the authors.
Yes
Does the work include the necessary controls?
If not, please specify which controls are required in your comments to the
authors.
Yes
Are the conclusions drawn adequately supported by the data shown?
If not, please explain in your comments to the authors.
Yes
Are you able to assess any statistics in the manuscript or would you
recommend an additional statistical review?
If an additional statistical review is recommended, please specify what aspects
require further assessment in your comments to the editors.
I am able to assess the statistics
Quality of written English
Please indicate the quality of language in the manuscript:
Acceptable
Declaration of competing interests
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questions:
1
. 
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salary from an organisation that may in any way gain or lose financially
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or in the future?
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Do you hold or are you currently applying for any patents relating to the
content of the manuscript?
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Have you received reimbursements, fees, funding, or salary from an
organization that holds or has applied for patents relating to the content of
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paper?
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