Comparison of Performance of Micro-Computed Tomography (Micro-CT) and Synchrotron Radiation CT in Assessing Coronary Stenosis Caused by Calcified Plaques in Coronary Artery Phantoms

Round 1

Reviewer 1 Report

This paper compares the ability to evaluate stenosis in coronary arteries in 3D-printed model coronary phantoms. It shows that the superior resolution of a commercial micro-CT compared to a synchrotron-based CT device resulted in more accurate characterization of the phantoms. I have two concerns:

1. The title of the paper does not reflect the actual study itself. A more appropriate title would be "Comparison of Performance of a Micro-Computed Tomography (Micro-CT) and a Synchrotron Radiation CT in Assessing Coronary Stenosis Caused by Calcified Plaques in Coronary Artery Phantoms", since the current title gives the impression of imaging actual coronary stenosis. Clinical assessment in patients is done currently with CTA, and the blooming issue mentioned in this paper is largely resolved with dual-energy CT.

2. Synchrotron-based CT can achieve the same or better resolution to tabletop micro-CT. It has been amply demonstrated in synchrotron nano resolution imaging. The paper compared specific systems. This point can be made more clear, and the stress should be put on the advantage of resolution in general in evaluating coronary stenosis.

Author Response

This paper compares the ability to evaluate stenosis in coronary arteries in 3D-printed model coronary phantoms. It shows that the superior resolution of a commercial micro-CT compared to a synchrotron-based CT device resulted in more accurate characterization of the phantoms. I have two concerns:

1. The title of the paper does not reflect the actual study itself. A more appropriate title would be "Comparison of Performance of a Micro-Computed Tomography (Micro-CT) and a Synchrotron Radiation CT in Assessing Coronary Stenosis Caused by Calcified Plaques in Coronary Artery Phantoms", since the current title gives the impression of imaging actual coronary stenosis. Clinical assessment in patients is done currently with CTA, and the blooming issue mentioned in this paper is largely resolved with dual-energy CT.

Response: Thank you for your comment. The manuscript title has been changed from “Comparison of Performance of Micro-Computed Tomography (Micro-CT) and Synchrotron Radiation CT in Assessment of Coronary Stenosis Caused by Calcified Plaques” to “Comparison of Performance of Micro-Computed Tomography (Micro-CT) and Synchrotron Radiation CT in Assessing Coronary Stenosis Caused by Calcified Plaques in Coronary Artery Phantoms” for addressing this comment.

2. Synchrotron-based CT can achieve the same or better resolution to tabletop micro-CT. It has been amply demonstrated in synchrotron nano resolution imaging. The paper compared specific systems. This point can be made more clear, and the stress should be put on the advantage of resolution in general in evaluating coronary stenosis.

Response: Thank you for your comment. For addressing this comment, the last two sentences of Abstract and the first two sentences of Conclusions have been changed to the followings. 

Abstract:

“Our results show that the high-resolution micro-CT used in this study outperformed the Australian Synchrotron SRCT in both calcified plaque and coronary stenosis assessment. These findings will become clinically important for cardiovascular event prediction and enable reclassification of individuals with low and intermediate risk into appropriate risk categories when the technical challenges of micro-CT in clinical practice such as the small field of view and demanding on image processing power are addressed.”

Conclusions: 

“Our results show that the high-resolution micro-CT used in this study outperformed the Australian Synchrotron SRCT in calcified plaques and coronary stenosis assessment with regard to blooming artifact reduction. This highlights the importance of using high-resolution imaging for the improvement of assessing calcified coronary plaques and a reduction in false positive rates. This study’s findings will become clinically important for cardiovascular risk prediction and allow reclassification of individuals with low and intermediate risk into the appropriate risk categories when the technical challenges of using micro-CT in clinical practice such as small FOV and highly demanding image processing power are addressed.”

Reviewer 2 Report

Dear authors,

I have studied with great interest the manuscript “Comparison of Performance of Micro-Computed Tomography (Micro-CT) and Synchrotron Radiation CT in Assessment of Coronary Stenosis Caused by Calcified Plaques”

The main question addressed by the research was compare performance of high-resolution micro-computed tomography with synchrotron radiation computed tomography in the assessment of calcified plaques and a previously published dataset of coronary stenosis assessment. The authors confirmed that that high-resolution micro-computed tomography outperforms synchrotron radiation computed tomography in both calcified plaque and coronary stenosis assessment.

The topic is original because this finding will become clinically important for cardiovascular event prediction and enable reclassification of individuals with low and intermediate risk into appropriate risk categories when the technical challenges of micro-CT in clinical practice such as the small field of view and demanding on image processing power are addressed. The manuscript is clearly exposed and well written, the text clear and easy to read. The figures and tables correspond to the description in the text, are well designed and reflect important information. The references are appropriate.

I have no comments to improve the quality of the presentation. I express my gratitude to the authors for their great work done.

Author Response

I have studied with great interest the manuscript “Comparison of Performance of Micro-Computed Tomography (Micro-CT) and Synchrotron Radiation CT in Assessment of Coronary Stenosis Caused by Calcified Plaques”

The main question addressed by the research was compare performance of high-resolution micro-computed tomography with synchrotron radiation computed tomography in the assessment of calcified plaques and a previously published dataset of coronary stenosis assessment. The authors confirmed that that high-resolution micro-computed tomography outperforms synchrotron radiation computed tomography in both calcified plaque and coronary stenosis assessment.

The topic is original because this finding will become clinically important for cardiovascular event prediction and enable reclassification of individuals with low and intermediate risk into appropriate risk categories when the technical challenges of micro-CT in clinical practice such as the small field of view and demanding on image processing power are addressed. The manuscript is clearly exposed and well written, the text clear and easy to read. The figures and tables correspond to the description in the text, are well designed and reflect important information. The references are appropriate.

I have no comments to improve the quality of the presentation. I express my gratitude to the authors for their great work done.

Response: Thank you for your comments.

Reviewer 3 Report

Curtise K. C. Ng et. al present an article regarding the comparison of performance of micro-Computed Tomography and Synchrotron Radiation CT in Assessment of Coronary Stenosis Caused by Calcified Plaques.

The manuscript is well-written, adding new fundumental data on this interesting topic and the figures are well presented. However, some notes need to be implemented.

1. Introduction: please, implement this paragraph by citing the latest ESC Guidelines on Chronic Coronary Syndromes.

2. A specific table should be added to indicate the use of these techniques in clinical practice and in which setting (e.g. acute or chronic coronary syndrome, risk stratification, etc).

3. It is recommended to conclude the discussion by indicating the "Future directions and perspectives" of these techniques.

Author Response

Curtise K. C. Ng et. al present an article regarding the comparison of performance of micro-Computed Tomography and Synchrotron Radiation CT in Assessment of Coronary Stenosis Caused by Calcified Plaques.

The manuscript is well-written, adding new fundamental data on this interesting topic and the figures are well presented.

Response: Thank you for your comments.

However, some notes need to be implemented.

1. Introduction: please, implement this paragraph by citing the latest ESC Guidelines on Chronic Coronary Syndromes.

Response: This has been included as suggested. Further, the introduction has been expanded.

2. A specific table should be added to indicate the use of these techniques in clinical practice and in which setting (e.g. acute or chronic coronary syndrome, risk stratification, etc).

Response: We thank reviewer’s suggestion on adding a table to show these protocols. However, given the limited FOV and super high resolution of micro-CT, it is impractical to compare the scanning protocols between micro-CT and standard medical CT scanning protocols. Our results emphasise the importance of using high resolution for improvement of assessing calcified plaques.

3. It is recommended to conclude the discussion by indicating the "Future directions and perspectives" of these techniques.

Response: This has been added as another section.