Review for 10.1186/S12876-017-0673-Y (2017)

Reviewer ’s report  
 
Title: Magnetic Resonance Imaging Analysis of Brain Function in Patients with Irritable Bowel  
Syndrome  
 
Version: 0 Date: 08 Jul 2017  
 
Reviewer: Anupam Guleria  
 
Reviewer's report:  
 
This fMRI study aimed to examine the relationship of vi sceral sensitivity in IBS patients with the 
cortical activity and to elucidate the role of psychological factors in the pathogenesis of IBS. 
There is already a significant body of work on rectal balloon distention based fMRI studies on 
patients with IBS an d this provides a modest increase in that body of knowledge. This is 
probably an interesting manuscript but is not acceptable in its present form and needs major 
revision before I can recommend it for publication.  
 
 
Major comments  
 
1. A lot of fMRI studies ba sed on rectal balloon distention have been reported in literature 
on patients with IBS and healthy controls. The authors did not give any discussion to 
such studies in the background section and also how the present study differs from such 
previous studies . For example, Yuan et al. 2003 performed a similar study at 30 ml, 60 
ml, 90 ml, and 120 ml rectal balloon -distention. The authors should discuss such a point.  
 
 
2. The description of stimulation protocol is insufficient. The difference between 30 -s 
stimul ation and 30 -s airbag dilation stimulation is not clear. Though it is understood that 
volume was 40, 80 and 120 ml for 30 -s airbag dilation stimulation, it is not clear that 
what was the volume of airbag for 30 -s stimulation? This should be described in mo re 
detail.  
 
 
3. A brief description about "Latin Square sequence stimulation" is required on Page 6.  
 
 
4. The description about the processing and analysis of fMRI data using SPM is missing. 
The detailed description is necessary. Please specify if all the thre e blocks viz. 30 -s rest, 
30-s stimulation, 30 -s airbag dilation stimulation were included in the analysis and if yes 
then mention the contrast of interest. Further the details of ROI analysis are required.  
 
 
5. Did the authors use uncorrected p statistics fo r multiple comparisons? Please provide 
justification and clarification if that is the case. It should also be included in manuscript.  
6. The authors have mentioned that to avoid the statistical error caused by artificial 
distinction, the left and right wer e not distinguished. This is not justifiable and the 
information of left and right hemisphere of activated brain regions is mandatory due to 
their different functioning. I suggest the authors to make a table of the activated brain 
regions with detailed inf ormation such as hemisphere, MNI co -ordinates etc.  
 
 
7. Is the proportion mentioned in the Figure 1 related to the area/volume of activated 
region?  
 
 
8. Figure 2, 3. It would be better with name tags indicating the regions on brain for readers 
who may not fam iliar with brain anatomy.  
 
 
9. No activation is observed in healthy controls even at 120 ml as clear from Figure 2.  
However, Yuan et al., reported a significant activation in healthy controls even at 60 ml. 
Please explain.  
 
 
10. Resolution of figure 3 is very  poor.  
 
 
11. Last line on Page 9, "Additionally, although the 80 ml stimulus failed to have a 
significant effect on female patients with IBS with disease duration < 5 years, the 40 ml 
and 120 ml stimuli increasingly activated brain regions in those subgroups ." What could 
be the reason of no activations at 80 ml though activations were observed at lower 
volume i.e. 40 ml.  
 
 
12. Page 11, Line 50 -52 "However, the activation of parietal, occipital, and temporal lobes 
have been previously rarely reported in the lite rature."  
 
There are several reports where the activation of these regions has been reported during 
rectal balloon distention. A very recent paper on mapping of brain activations to rectal 
balloon distension stimuli (see the link 
http://www.jnmjournal.org/j ournal/view.html?uid=1302&vmd=Full& ) has clearly 
reported the activations in parietal lobe, temporal lobe and fusiform gyrus (a part of 
occipital lobe). Such papers should be referred here.  
 
 
13. Page 13, Line 1, "Thus, it is possible that the subgroup of pa tients with anxiety or 
depression scores < 9 points were the only pati ents in the cohort who actually had IBS."  
 
Does it mean that the patients having anxiety or depression scores > 9 points do not have 
IBS? But it is pointed in the methods section that all  recruited patients with IBS met the 
ROME III criteria. Please explain.  
 
 
14. The severity of symptoms of IBS should be included. It will give an idea that how the 
severity varies for patients with anxiety or depression scores greater than and less than 9 
points.  
 
 
15. Since volume -based manual dilation is inaccurate method and pressure -related distension 
using barostat is recently accepted as standard, the authors should mention it as a 
limitation.  
 
 
16. The average hemodynamic response over time should be plot ted to support the adequacy 
of methodology as all the procedures were done manually.  
 
 
Minor comments  
 
1. Page 3, Results section in abstract, line 57 -58, Repetition of the following lines in the 
same paragraph (the first line is also same).  
 
"The anxiety and depression score of patients with IBS was significantly different from 
healthy controls (P<0.05)."  
 
2. Page 3, Results section in abstract  
 
"Further, the brain regions that were activated at a stimulus dilation of 40 ml versus 120 
ml, and at 80 ml versus 120  ml were significantly different (P<0.05)."  
 
The authors should mention the names of brain regions here also as it will give a quick 
glimpse of results presented in the paper to the readers. Similarly in the last line of this 
section.  
 
 
3. Please define abbreviations before use e.g. CI.  
 
 
4. Repetition of following lines in discussion section: "The visceral sensory nerve center of 
the brain is composed of the ACC, IC, PFC, and THAL."  
 
 
5. Page 12, line 57, 'We cannot completely rule out the p ossible that' possible should be 
replaced with possibility.  
Are the methods app ropriate 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, 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.  
 
Not relevant to this manuscript  
 
Quality of written English  
Please indicate the quality of language in the manuscr ipt: 
 
Acceptable  
 
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, fees, funding, or salary from an  
organisation that may in any way gain or lose financially from the publication of this  
manuscript, either now or in the future?  
 
2. Do you hold any stocks or shares in an organisation that 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 reimbursements, fees, funding, or salary from an organization that 
holds  or has applied f or 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 relation 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.  
 
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