Review for 10.1186/s12876-020-01228-9 (2020)

Reviewer ’s report  
 
Title: Diagnosis of vascular invasion in pancreatic ductal adenocarcinoma using endoscopic 
ultrasound elastography  
 
Version: 0 Date: 11 Feb 2020  
 
Reviewer: Stefano Francesco Crinò  
 
Reviewer's report:  
 
In this retrospective study, Authors aimed to evaluate the role of EUS elastography for the 
vascular staging of pancreatic cancer.  
 
The conce pt is interesting and the manuscript is well written. However, this study has several 
limitations.  
 
 
Methods:  
 
- In an inclusion period od about 4 years, Authors used several different scopes and 
ultrasound machines. Moreover, both radial and linear echoendo scopes were used. I have 
a concern that the use of different machines may have impacted the results.  
 
- Because of the retrospective design of the study and the relatively long inclusion period, 
it is likely that the elastography technique used was not stan dardized for all patients. Did 
you perform EUS -EG with the purpose of vascular staging in all patients? Or you 
reviewed the images of elastography performed "simply" for tumor characterization?  
 
- Which was the definition of vascular invasion on surgical pathology? How many vascular 
resections were performed for pancreatic head lesions? I guess it is easy to pathologically 
evaluate the vascular invasion of splenic vein/artery when these vessels are resected 
during distal pancreatectomy, but how you evaluated the vascular infiltration in 
duodenopancreatectomy specimens?  
 
- You stated: "Both EUS -EG and EUS B -mode findings were retrospectively reviewed by 
two gastroenterologists". What exactly you review ed? I guess the EUS images. How 
many elastography images were available per patient? How many cases of discrepant 
findings did you observe?  
 
- Difficult cases were selected based on CT finding of tumor contacting vessels. How did 
you evaluate the diagnosti c ability of CT in this subgroup? Did you consider the final 
opinion of the radiologist? How many of these patients were clearly evaluated on EUS 
B-mode?  
 
- 14 patients had a tumor that contacted no vessels. These cases should be excluded 
because the vascul ar staging was clear.  
 
- Were dynamic CT performed using a pancreatic protocol in all cases?  
 
- You stated: "Of subjects in whom vascular invasion was not assessed in EUS -EG...". It 
seems that EUS -EG was not performed in all cases. This could bias the result s if more 
"difficult" cases had been evaluated only on CT or EUS B -mode. How many "difficult" 
patients underwent EUS -EG? An analysis of patients who underwent all three modalities 
should be performed.  
 
- "The interobserver agreements of EUS B -mode and EUS -EG findings for vascular 
invasion were moderated (κ=0.596, P &lt;0.0001) and substantial (κ=0.634, P &lt;0.0001). 
What the p -value refers to?  
 
- In how many patients the finding was "an abnormal vessel missing a hyperechoic layer 
vascular surface" on EUS B -mode? This is the most difficult situation where EUS -EG 
could add some value.  
 
Are the methods appropriate and well described?  
If not, please specify what is required in your comments to the authors.  
 
No 
 
Does the work include the necessary controls?  
If not, plea se specify which controls are required in your comments to the authors.  
 
No 
 
Are the conclusions drawn adequately supported by the data shown?  
If not, please explain in your comments to the authors.  
 
No 
 
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 speci fy what aspects require further 
assessment in your comments to the editors.  
 
I am able to assess the statistics  
 
Quality of written Engli sh 
Please indicate the quality of language in the manuscript:  
 
Needs some language corrections before being published  
 
Declaration of competing interests  
Please complete a declaration of competing interests, considering the following questions:  
 
1.  Have  you in the past five years received reimbursements, f ees, funding, or salary 
from an organisation that may in any way gain or lose financial ly from the 
publication of this manuscript, either now or in the future?  
 
2.  Do you hold any stocks or shares in an organisation t hat may in any way gain or 
lose financially from the publication of this manuscript, either now or in the 
future?  
 
3.  Do you hold or are you currently applying for any patents  relating to the content 
of the manuscript?  
 
4.  Have you received rei mbursements, fees, funding, or salary from an organization 
that holds or has applied for patents relating to the content of the manuscript?  
 
5.  Do you have any other financial competing interests?  
 
6.  Do you have any non -financial competing interests in rela tion to this paper?  
 
If you can answer no to all of the above, write 'I declare that I have  no competing interests' 
below. If your reply is yes to any, please give details below.  
 
I declare that I have no competing interests  
 
I agree to the open peer review p olicy of the journal. I understan d that my name will be included 
on my report to the authors and, if the manuscript is accepted f or publication, m y named report 
including any attachments I upload will be posted on the website along with the authors' 
respon ses. I agree for my report to be made available under an Open Access Creative Commons 
CC-BY license ( http://creativecommons.org/licenses/by/4.0/ ). I understand that any comments 
which I do not wish to be included in my named report can be included as confi dential comments 
to the editors, which will not be published.  
 
I agree to the open peer review policy of the journal