Review for 10.1186/s12876-025-03637-0 (2025)

Title: Pilot feasibility study to determine the utility of direct access and quantitative magnetic
resonance cholangiopancreatography (MRCP) in the assessment of suspected acute biliary or
ductal gallstone presentations.
Version: 2 Date: 29 Oct 2024
Reviewer's report:
Congratulations on completing your study, especially through the trials of early COVID. The
focus on direct MRCP for cost effectiveness is an interesting and possibly useful one. The paper
as written has some confusing elements and perhaps too broad of scope that distract from the
information provided.
Abstract
- In the Method section, "suspected acute gallstone disease and abnormal were randomized"...
I assume that should be "abnormal LFTs"?
Background
- Citation numbering is out of order in the first two paragraphs, going from 5 to 10-13 to 6-9 to 14
- You state that US has concerns about sensitivity and user dependence but also cast doubt on
the reproducibility of MRCP in the abstract. Are there data comparing the  accuracy of the two
modalities that could provide clarity?
- Your citation 15 used to show that inter-reader variability is high in qualitative MRCP only
applies to PSC patients. To suggest that MRCP is also variable for the identification of gallstones
is disingenuous and should be removed, or a different citation should be provided to support
this claim
Methods
- Why was 16 hours used as the time cutoff for direct MRCP evaluation? This seems arbitrary
- It is somewhat unclear in the Procedures section who decides on what imaging. Did all patients
in the direct MRCP arm get an MRI regardless of the surgical team's assessment or could that
be overruled?
Health Economic Methodology
- Perhaps the most confusing issue here is the idea of time to diagnosis, described as "receipt
of diagnostic report." Receipt by whom? The clinical team? The patient? The time that the
interpreting radiologist signed the report? Throughout the paper it is also unclear what  "final"
means  in terms of imaging. Does it mean the last imaging exam performed before discharge
or surgery, regardless of modality?
- "Definitive diagnosis" as the presence or absences of gallstones. Does this mean
cholecystolithiasis only? Or do you include choledocholithiasis when you say gallstones? This
is an important distinction, because if you are only assessing for stones in the gallbladder itself
then you are likely over-estimating the ability if MRI and ultrasound to provide a definitive
diagnosis, as stones in the CBD are generally more difficult to see than stones in the gallbladder
Outcomes
- Your definition of what is a primary and secondary outcome is not consistent between this
section and the Background. This should be corrected to avoid confusion
Data and Statistical Analysis
- Reference #17 has no names listed
Results
-  It might be useful to describe why your number enrolled is less than half of your power
calculation earlier in the paper. It was jarring to see 27 listed here after just reading about and
anticipated enrollment of 64
- I would suggest that the study flowchart be included as a primary instead of a supplementary
figure.
- There are several confusing aspects of how patients wound up in the different arms of the
study that need to be more clearly addressed. 13 patients were assigned to standard of care but
only 11 were analysed, why was this? Why did one patient in the standard group get a direct
MRCP? In which group was their data analyzed?? Why were the two patients assigned to the
direct group who did NOT receive MRCPs still included in the direct group analysis? All of
these questions should be clearly addressed-and necessary data re-analyzed) as they have the
potential to seriously affect the results of the study (especially with small enrollment numbers)
- In Table 2, the imaging cost numbers in the Standard of Care columns don't appear to add
up correctly
- "Final diagnostic report" is used again here and remains ambiguous. Final report regardless
of modality?
- How were patients "later" diagnosed with CBD stones for the cases in Supplementary Figure
3? ERCP? If so, was ERCP more likely in patients in the standard of care or MRCP arm, and
how did that affect the overall cost?
- I fail to see how the inclusion of MRCP+ data adds to this paper's aims. You say at one point that
MRCP+ data was withheld from the clinical team, but was it available for the radiologist to make
their determination of "gallstones?" Did the radiologists rely on gallbladder or biliary volumes
to make their diagnoses? Since you were unable to perform a comparison between standard
MRCP and MRCP+, I fear that including information about MRCP+ in this paper distracts from
its primary objective, and suggest that this data should be removed
Discussion
- The increased dilation of the CBD and whole biliary tree volumes was not statistically
significant and therefore should not be so strongly emphasized in paragraph 3. Again, what
utility does the MRCP+ data add to this study?