Feasibility of Ultra-High Resolution Supra-Aortic CT Angiography: An Assessment of Diagnostic Image Quality and Radiation Dose
Round 1
Reviewer 1 Report
General statement: This study is clinically relevant and the manuscript is well written. However, there are some issues regarding this manuscript in the current version. Therefore, minor revisions are needed to improve this work.
Title: Sound
Abstract: Well structured
Introduction: The scientific background and the purpose of this study are well summarized.
MM:
Page 3 Line 74: Who assessed the sufficiency of intra-arterial contrast? Provide more information regarding this decision process.
In general, a comparison to other imaging modality techniques including other CTA protocols or MRA would improve this study. The lack of comparsion should be stated as a limitation in the discussion.
Results: well presented
Dicussion:
As mentioned, the lack of comparsion with other imaging modality techniques including other CTA and MRA protocols should be stated as a limitation in the discussion. Are there comparable studies ?
What are your implications for clinical routine? Should the applied CTA protocol used in every scan if possible? Any exceptions? Please discuss this aspect in more detail.
There are some spelling and grammar mistakes, please revise.
References: Please revise according to the journal's guidelines.
Tables: Appropriate
Figures: Good
Author Response
Dear Reviewer 1,
Thank you very much for your valuable comments, according to which we extensively revised our manuscript. A native speaker corrected grammatical errors as well as the English language style.
- “Page 3 Line 74: Who assessed the sufficiency of intra-arterial contrast? Provide more information regarding this decision process. "
>> We appreciate this comment and have clarified statements regarding cohort inclusion.
“55 consecutive patients (23 men, 32 women, mean age 70.5 years; age range: 37-88 years) who underwent supra-aortic UHR-CTA in our institution were recruited. Of them, five patients did not meet the inclusion criteria due to poor image qualities (beam hardening artefact, distinct motion artefacts) insufficient intra-arterial contrast, or in case, patients could not receive a bolus of contrast medium at a flow rate of 5 ml per second (4 women, 1 man, mean age 60; ranging from 23 - 81 years). A neuroradiologist with 10 years of experience assessed sufficient arterial contrast required for inclusion in the cohort. A final number of 50 participants were subjected to our analysis (n=50; 22 men, 28 women; mean age 70.5 years; age range: 37 - 88 years).”
- "In general, a comparison to other imaging modality techniques including other CTA protocols or MRA would improve this study. The lack of comparsion should be stated as a limitation in the discussion."
>>Thank you for your important remark. We have elaborated on our limitations.
“This study has limitations. First, the retrospective design is associated with a certain selection bias, and the small sample size prevents a pathology-focused assessment of the included cases. The lack of comparison with a normal resolution CT sets an additional limitation to this study. However, our assessments represent an initial evaluation of the diagnostic image quality of the novel UHR-CTA as a basis for future pathology-focused diagnostic accuracy studies. Even though with limited informative value, our findings strongly suggest a highly valuable diagnostic potential of UHR-CTA, presenting with excellent qualitative and quantitative image qualities and concomitant moderate radiation doses. UHR-CTA is therefore likely to introduce new perspectives in neurovascular imaging. This study has limitations. First, the retrospective design is associated with a certain selection bias, and the small sample size prevents a pathology-focused assessment of the included cases. The lack of comparison with a normal resolution CT sets an additional limitation to this study. However, our assessments represent an initial evaluation of the diagnostic image quality of the novel UHR-CTA as a basis for future pathology-focused diagnostic accuracy studies. Even though with limited informative value, our findings strongly suggest a highly valuable diagnostic potential of UHR-CTA, presenting with excellent qualitative and quantitative image qualities and concomitant moderate radiation doses. UHR-CTA is therefore likely to introduce new perspectives in neurovascular imaging.”
- "As mentioned, the lack of comparison with other imaging modality techniques including other CTA and MRA protocols should be stated as a limitation in the discussion. Are there comparable studies?”
>>Thank you for your advice. We have contextualised the study even further.
“Studies on coronary artery and small visceral artery CTAs [11, 12] have recently shown that the UHR-CT system is highly suitable for a significant improvement of image quality, SNR, CNR and an enhanced vascular imaging.”
- "There are some spelling and grammar mistakes, please revise.
>> As mentioned above, proofreading was carried out by a native speaker.
- "What are your implications for clinical routine? Should the applied CTA protocol used in every scan if possible? Any exceptions? Please discuss this aspect in more detail"
>>Thank you very much for highlighting this point. We have discussed this point in further detail.
“This study has limitations. First, the retrospective design is associated with a certain selection bias, and the small sample size prevents a pathology-focused assessment of the included cases. The lack of comparison with a normal resolution CT and its dose exposure sets an additional limitation to this study. However, our assessments represent an initial evaluation of the diagnostic image quality of the novel UHR-CTA as a basis for future pathology-focused diagnostic accuracy studies.”
- References: Please revise according to the journal's guidelines."
>> done.
Reviewer 2 Report
General comments:
The authors evaluated the clinical feasibility of a new ultra-high-resolution CT technology in the setting of neuro-CT-Angiography. The authors nicely show very good depiction of cerebral vessels. Especially small and peripheral vessels may benefit from the increased spatial resolution. Quantitative and qualitative analyses were done with good results. Interestingly, radiation dose was moderate. Iterative reconstruction may have led to these moderate dose levels while keeping image quality satisfactory. The manuscript is well-written and the results are of particular relevance. The technology may have the potential to increase diagnostic performance of CTA in neurovascular disease. Minor language editing needs to be performed and the following specific comments need to be addressed before eventual acceptance.
Specific comments:
Title: Please remove „comprehensive“
Abstract:
Background: ok
Methods: ok
Results: ok
Conclusion: Omit “further”
Keywords: Please make sure you are using MeSH Terms
Introduction: Well-written. Please index the abbreviation “CT“appropriately.
Materials and Methods:
Patients: The sentence “CTA images of 55 consecutive patients (23 men, 32 women, mean age 70.5 years; age range: 37-88 years) who underwent supra-aortic UHR-CTA in our institution.” Is incomplete.
Statistical analysis: add the agreement methodology to this part.
Results:
Ok
Discussion:
“It should also be emphasized at this point that even the smallest perforating arteries” Please rephrase. This sentence is striking, please rephrase.
Please replace “Despite that, UHR diagnostics” with “However, UHR-CTA…”
Line 293: Please stick to the abbreviation UHR-CTA. Furthermore, this sentence is too strong. Please tone it down.
Please discuss the resulting radiation dose in further detail.
Conclusion: Omit “further”
References: ok
Figures: Very nice
Tables: ok
Author Response
Dear Reviewer 2,
Thank you for the reviewing our manuscript and your valuable remarks.
We hope we were able to improve the suggested and constructive comments and criticisms. A native speaker corrected grammatical errors as well as the English language style.”
- "Title: Please remove „comprehensive“"
>>Thank you. The title has been revised.
- "Conclusion: Omit “further”"
>> Done.
- "Patients: The sentence “CTA images of 55 consecutive patients (23 men, 32 women, mean age 70.5 years; age range: 37-88 years) who underwent supra-aortic UHR-CTA in our institution.” Is incomplete."
>> Thank you for your remark. We corrected the sentence according to your comment.
- "Statistical analysis: add the agreement methodology to this part."
>>Thank you. We now added the agreement methodology.
“Mean, median and standard deviation and interrater reliability for continuous variables were calculated (Cohens-kappa-coefficient) and determined using SPSS (IBM SPSS Statistics for Windows, Version 23.0. Armonk, NY: IBM Corp.).”
- “It should also be emphasized at this point that even the smallest perforating arteries” Please rephrase. This sentence is striking, please rephrase.
>>Thank you for your remark. We rephrased the sentence and contextualized it.
“In particular, a high vascular contrast and a distinctly defined demarcation of the extracranial as well as the intracranial vessels could be demonstrated. Noteworthy, even the smallest perforating arteries (e.g. LSA, as shown in Fig.3) vascularizing the deep brain structures become diagnostically accessible by UHR-CTA, which is generally not the case when using conventional CTA.”
- Please replace “Despite that, UHR diagnostics” with “However, UHR-CTA…”
>> Done
- Line 293: Please stick to the abbreviation UHR-CTA. Furthermore, this sentence is too strong. Please tone it down.
>>We have replaced and corrected these sentences.
- Please discuss the resulting radiation dose in further detail.
>> We appreciate the reviewer’s important comment. We now elaborated on radiation dose in further detail.
“The lack of comparison with a normal resolution CT and its dose exposure sets an additional limitation to this study. However, our assessments represent an initial evaluation of the diagnostic image quality of the novel UHR-CTA as a basis for future pathology-focused diagnostic accuracy studies. Even though with limited informative value, our findings strongly suggest a highly valuable diagnostic potential of UHR-CTA, presenting with excellent qualitative and quantitative image qualities and concomitant moderate radiation doses. UHR-CTA is therefore likely to introduce new perspectives in neurovascular imaging.”
