Review for 10.1186/1471-230X-13-2 (2013)

Reviewer's report
Title:Quantitative low mechanical index contrast-enhanced endoscopic
ultrasound for the differential diagnosis of focal pancreatic masses
Version: 1Date:5 September 2012
Reviewer: Michael Hocke
Reviewer's report:
Review:
1. Is the question posed by the authors well defined?
The aim of the study is clearly defined and answered.
2. Are the methods appropriate and well described?
The method is appropriate and reasonable described.
3. Are the data sound?
The data are preliminary however, this is pointed out in the amnuscript.
4. Does the manuscript adhere to relevant standards?
The manuscript is well written and adequate.
5. Are the discussion and conclusions well balanced?
The discussion should be revised - see comment: Major revision.
6. Are the limitations stated?
There are stated at the end of the manuscript.
7. Do the authors clearly acknowledge any work ....?
See Major revisions.
8. Do the title and abstract accurately...?
The title should be changed. The original title implicates that the articel is about
differential diagnosis of pancreatic masses. In fact the authors are dealing only
with two entities of focal pancreatic masses, namely chronic pancreatitis and
pancreatic carcinoma. Other pancreatic masses like neuroendocrine tumors are
not target of the study, therefore the title should only name the investigated
entities. The same problem arises in the introduction of the abstract.
9. Is the writing acceptable?
There are minor spelling mistakes.
a) Major revision:
The study is about the value of low mechanical index contrast enhanced
endoscopic ultrasound for the differential diagnosis of chronic pancreatitis and
pancreatic carcinoma. The main advantage of the study is the introduction of an
automatic analysing system to avoid investigators bias in the interpretation of the
contrast enhanced frames.
In the reviewers view, the present work has some limitations which could be
easily corrected by the investigators group:
1.The process of lo mechanical index CE EUS is described in "Methods".
However the changeable values of the machine settings are not given. In low
contrast enhanced CE EUS the mechanical index can be increased to produce
better picture quality and many work groups do not use the oroginal settings of
the Hitachi company. The change of the setting however can influence the result
and should be therefor given in the manuscript. (Picture value of MI was 0.20
what does not compare to the original machine setting)
2. CELMI EUS is a very resent method and probably comparable with CT or MRI
studies. It certainly is comparable with percutaneous contrast enhanced
ultrasound studies because of basically the same technique. The actual literature
of sonography, CT, and MRI shows a high variety of results of contrast studies in
the discrimination of focal pancreatitis and pancreatic carcinoma. The authors
should discuss these results in connection to the advantages of their method and
point out the possible differencies. This would give the reader a basic
understanding of the advantages and disadvantages of CELMI EUS. (Problems:
10% hypervascularized pancreatic carcinoma?, focal necrosis in chronic
pancreatitis as a reason for lack of enhancing effect in chronic pancreatitis ->
relation to the relativly low number of patients).
3. One study was already published about the same procedure with the same
differential diagnosis with a less promising result for CELMI EUS. The study was
citated by the authors however not discussed. To explain the differenties of the
findings, the study should be mentioned in "discussion". The possible difference
like the use of an automatic analyzing system or the relativly low number of
patients in both studies should be mentioned.
4. High MI contrast enhanced endoscopic ultrasound is meanwhile established
and recommended in the European Guidelines of non liver contrast enhanced
ultrasound. The guidelines should be mentioned in the manuscript and the basic
difference between the two methods (CELMI EUS and CEHMI EUS) pointed out
in the discussion. This would have the advantage that a non specialist reader
does not get confused in this highly sophisticated field.
5. The authors should point out the process of chosing the ROI in the chronic
pancreatitis and pancreatic carcinoma. In the view of the reviewer the best ROI
would be the whole lesion. Because of the postprocessing of the videos the ROI
could be placed in any area and the result could be influenced. In addition it is
hard to point out a lesion for comparison in patients with focal pancreatitis
because of the lack of a difference in the EUS picture (picture example - chronic
pancreatitis). The authors should state the placing and the size of the ROI in
general.
Minor Revision:
Spelling mistake of "Eundoscopic Ultrasound" in Chapter Backround
Missing meaning of the sentence: Furthermore, it has the added benefit of
biological material sampling without risk of tumor seeding. This sentences is
referring to CEH EUS but should refere to Fine needle aspiration.
Level of interest: An article of outstanding merit and interest in its field
Quality of written English: Needs some language corrections before being
published
Statistical review: Yes, but I do not feel adequately qualified to assess the
statistics.
Declaration of competing interests:
'I declare that I have no competing interests'