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Abstract – Study dates
Location: Abstract, 2nd sentence: “…between March 11, 2023, to March 31, 2023, and excluded 375 cases.”
Comment: “Not consistent with dates in the manuscript.”
Page 5 17.58 mGy • cm and 0.16 mS\l,
Comment: "What was nominal DLP and ED?"
Many Citations are Dual Energy yet the imaging studies performed appear to be done at a single energy.
This change in approach changes beam hardening artifacts.
Figure 1 left side " traditional two issues" not following what this is for.
Page 7 - How often was the scanner recalibrated? several years results will drift.
Page 9 - "“We retrieved data on 723 patients who underwent head and neck CTA at our hospital from March 11, 2022, to March 31, 2024, and excluded 375 patients who did not meet the established criteria"
Comment - Include the number of people selected. making the reader do the math does not instill confidence in the work. it appears to try and downplay the size of the study. You only had 348 included iin the study .. < than1/2 the indicated size and even less than the excluded population.
Page 10:
Comments more specificity of flow rate, duration, and periodicity should be included to allow the reader to
discriminate the differences between the protocols,why were different injection propotocols done in the earlier studies before march 25, 2023 and
after? Why did the protocol change?
page 12: “…60 mL of contrast, followed by a second phase that injected 40 mL of saline. The flow rate was 5 mL/s and the total injection duration was 20 minutes. Conversely, the pulse group was administered a pulsed multi-phase contrast injection protocol. In this group, the first phase injected 35 mL of contrast, followed by the second phase with 5 mL of saline. From the fourth to the fifth phase, the contrast agent and saline were alternately injected to achieve mixed injection of them. The injection volume of contrast agent or saline was 5 mL per phase.”
Comment - 20 minutes for an injection of 5mUs would be 6 Liters of media????
what does a pulsed multiphase injection look like? flow rate for duration, repeat rate total volume, etc .... refer to table 2
Page 15 - only 2 image quality reviewers will have a bias.
Page 16: “The CT attenuation values of the arteries in both groups exceeded 300 HU.”
Comment - how was this assessed? average over some ROI? averaged over vessel segment? how was the ROI determined?
Page 17 Table - How were ROI's defined?
Page 18 What are the image quality metrics the clinicians are evaluating?
Page 20 “using dual-flow technology effectively reduced the beam hardening artifacts caused by high-attenuation contrast in veins and the right ventricle in CCTA examinations.[12] The CT attenuation value of veins were decreased by approximately 46%, which aligns with our research findings. In our protocol, the amount of contrast agent was reduced by 5 mL compared to Cao’s protocol.”
comment: citation 12 uses subjective results on on ly 24 cases to characterize beam hardening
"Cao’s protocol" needs clarification of what the protocol is or at least a citation.
Page 22: "“approach reduces beam hardening artifacts, improves image quality, and decreases the contrast dose."
comment; how was this assessed or measured. it appears the authors are repeating someone elses results without performing any analysis here.
An argument was made that both contrasts agent dose and radiation dose are reduced. Though there may be bias, in having only two observers judge image quality.
Conclusions on beam hardening are not founded in this paper.
comment; how was this assessed or measured. it appears the authors are repeating someone elses results without performing any analysis here or it appears to be relying on work not published here for this claim.
The authors present the results from a retrospective study to determine the feasibility of a pulsed multiphase contrast media injection scheme in head and neck computed tomography. Overall the article is well presented.
One major inconsistency is the description of the pulsed multiphase injection throughout the article.
In the abstract in page 3 it says " 30 ml of contrast media, followed by alternating injections of 15 ml of contrast media and 15 ml of physiological saline, and concluding with additional 35ml of physiological saline.
In methods and material line 131 it says for pulsed multi-phase contrast injection protocol, first phase 35 ml of contrast followed by second phase with 5ml of saline. From the fourth to fith phase the contrast agent and saline were alternatively injected to achieve mixed injection of then at 5ml per phase
Figure 2 shows different interpretation of the description.
From this inconsistency its hard to evaluate the usefulness of this method and this work.
In the methods and materials section in line 130 and 134 the authors indicate the flow rate as 5mL/s and the injection duration was 20 minutes. This is very confusing, since simple mathematics would suggest the total volume for the above condition was 6000mL which is a lot of fluid to give a patient.
Well presented with proper statistical analysis.
In my opinion there are a few inconsistencies in the experimental design
1) Choice of x-ray exposure parameters for the two types of injection. the authors claim lower dose to the patient when using pulsed injection, but the kv used for the spin was manually selected to be lower than conventional injection.
2) Table 1 indicates pulse group used 60mL of contrast and 55 ml of Saline. Conventional group had 75 mL of contrast and 40 mL of saline. Why not use the same total contrast and saline for both groups. Will the results change when contrast in conventional group is lowered from 75 ml to 60ml and saline in increased from 40ml to 55ml.
The authors claim the pulsed injection method
1) reduces contrast agent dose: Table 2 show the contrast difference was 15 ml . Why not do the same for the conventional group and see if the findings are any different
2) lowers radiation dose: Lower100 kV was chosen for pulsed group compared to conventional group 120 kV. Why not keep the kV same in the both.
3) minimized beam hardening artifacts: Why not use lower concentration iodine and check if the results are any different.
4) Enhances quality of head and neck CTA images: The findings show there is no statistical difference in SNR and CNR of target vessels between two groups. There was no statistical difference in CT values of target vessels between the two groups except for subclavian vein and superior vena cava. Why not use lower contrast concentration in conventional group to get similar HU of subclavian vein and superior vena cava.
The figures must be designed for black and white printing as well. For example figure 2 on black and white print show no difference between contrast media and NaCL.
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