Review for 10.1186/1471-230X-12-83 (2012)

Reviewer's report
Title:Capsule endoscopy with flexible spectral imaging color enhancement
reduces the bile-pigments effect and improves the detectability of small bowel
lesions.
Version: 1Date:23 March 2012
Reviewer: Edward Ciaccio
Reviewer's report:
Capsule endoscopy with flexible spectral imaging 1 color enhancement reduces
the bile-pigments effect and improves the detectability of small bowel lesions.
Eiji Sakai et al.
All suggestions are major and compulsory unless otherwise noted.
General Comments
In this study the investigators report on an method for improved detection of
small bowel lesions by capsule endoscopy (CE) trainees. The method is based
on RGB color filtering of videocapsule images that were obtained in a selected
12 patients. In these patients a total of 142 lesions were identified by two capsule
endoscopy experts. In the study the affect of degree of quality of bowel
preparation and when bile pigments are present on lesion detection was also
determined. Overall, the investigators found that detection by the trainees can be
improved by using color filtering of capsule endoscopy images with a flexible
spectral imaging color enhancement (FICE) setting of 1.
This study is likely to be of interest as a technique to improve readability of
capsule endoscopy images by trainees, and even by experienced endoscopists.
It would be helpful to shorten training time and improve accuracy. The ability of
color filtering to visually improve image quality and enhance detail has been
shown in prior studies. Yet, there is no actual quantitative increase in the
information content contained in the filtered images. Rather, the information
content is reduced, while ideally only salient information is retained.
I do however have some reservations with the study in its current form. Several
aspects of the methodology are unclear to me. Specifically, it is unclear how the
concurrence between the two expert CEs was determined when identifying 142
lesions. Ideally, both expert CEs would identify lesions blindly, and the
concurrence rate would be determined between them. Also, I wonder how
detection by trainees differed based upon the two lesion types. I am also unsure
whether it is statistically valid to pool videos, patients, lesions, and trainee results
together for purposes of classification, as I think was done in the study. This
makes N large but it may not be valid to do so. It is also unclear exactly what the
final value of N was for each test. Furthermore, I am uncertain whether all
trainees inspected all four color filtering types or not.
In the Specific Comments section I do also have some detailed remarks.
Specific Comments
P3 Abstract
‘A total of 60 angioectasia, 26 were identified by conventional CE; 40 by FICE
setting
4 1; 38 by FICE setting 2; 31 by FICE setting3;’
Not sure what this is reporting – there were four trainees. Did only one of the four
trainees evaluate each particular lesion? If so then justify the statistically validity.
‘…. with significant differences at FICE 5 setting 1 and 2 (P=0.0017 and P=0.014,
respectively).’
Significant differences with respect to what?
P8
‘Each CE video was viewed 5 under all the four settings (for example, case1;
trainee A: conventional, B: setting 1, C: 6 setting 2, D: setting 3).’
So, not all trainees reviewed videos under the same filtering conditions? Then
how was this selected for? Did trainee A always review conventional, etc.? Is this
valid for statistical purposes?
Results p9
Is the data in Table 1 pooled? If so, justify pooling of both observers (trainees)
and lesions.
P10
‘For each thumbnail, the RBG value …’
What is a thumbnail? Is it a white circular area? Needs to be stated. Thumbnail
has not been defined.
‘… the RBG value and brightness (1 average of ten mucosal 2 points
surrounding the small bowel lesion …’
Why 'surrounding' the small bowel lesion? Why not within the small bowel lesion
area?
‘To evaluate the factor that would be most useful for defining whether bile
pigments are present or not, ROC 4 analysis was performed’
What are the sensitivity and specificity? What is being tested? What thresholds
are used for the RGB levels if any?
‘ROC analysis revealed that the B value was the most useful … ’
This is the first time that 'B value' is introduced in the manuscript, and it is never
defined.
‘Based on this this finding, we set the cutoff value at 71.8 …’
‘this’ is repeated. 71.8 – what are the units?
I am not sure that N = 4 is enough readers.
P 12 bottom
‘Although our results indicated the potential clinical usefulness of CE-FICE, there
are
18 some limitations in this study’
Should be start of a new paragraph with subheading ‘Limitations’.
P21
‘Visibility was evaluated using a 4-point qualitative evaluation scale: A=excellent,
10 visualization of # 90% of the mucosa, no or minimal fluid, debris and bubbles
… ’
How was the percent coverage determined? How were fluid, debris, and bubbles
defined?
P22
‘(ROC) analysis revealed that the B value is the most useful factor to determine
the bile
pigments condition (area under the curve (AUC): 0.95, P<0.0001) (C).’
What is a B value? If it pertains to the RGB measurement it must be stated. And
how does this relate to Figure 1?
P22 Table 1
Are these averages for all trainees? Is this pooled data for all trainees? Did the
four trainees each evaluate all 142 lesions? The authors should justify their
statistical methodology.
P23
‘… FICE settig …’
setting
Figure 3
This figure really needs a better explanation. What is AUC? Please explain all
aspects of the table, the ROC curve, and the image white circles and why they
were selected.
Level of interest: An article whose findings are important to those with closely
related research interests
Quality of written English: Needs some language corrections before being
published
Statistical review: Yes, and I have assessed the statistics in my report.
Declaration of competing interests:
I declare that I have no competing interests.