Dual-Energy CT Arthrography: Advanced Muscolo-Skelatal Applications in Clinical Practice

Round 1

Reviewer 1 Report

The authors aim to provide an overview of the potential DECT-applications for CT arthrography. The article is well structured, easily comprehendible and well written in general. 

However, I would appreciate if the authors focused more on the following issues and provided a more critical interpretation of some aspects:

-       What is the clinical need for VNC CT-A (3D reconstructions, VRT required by surgeons was only briefly mentioned without great detail)

-       I would like to see a critical discussion of sensitivity and specificity of BME-imagines. In my clinical experience, especially specificity is quite low (I am aware of multiple publications stating its feasibility). Possible drawbacks: high bone density, you patient age, etc..

-       The chapter “metallic artifact reduction” seems a little short. Drawbacks of presented MAR option could be altered image information, altered hyper-/hypodense artifacts at different VMI levels, etc..

-       DECT seems hardly suitable for assessing tendons and ligaments compared to MRI. I would expect a more critical presentation.

Outlook new imaging techniques? Especially photon-counting CT may provide substantial benefits, e.g. by means of UHR scans without dose penalty (compared to EID detectors and Siemens Somatom Force which requires an additional comb filter for UHR mode). However, BME is not yet supported by PCD software while all 

Minor language issues throughout the manuscript ought to be corrected, possibly be a native speaker (e.g.: Line 25: minor language issue - “map” ought to be plural; Line 35: “jointlesions” ought to be 2 words, please omit the following semicolon.)

Author Response

REV 1

The authors aim to provide an overview of the potential DECT-applications for CT arthrography. The article is well structured, easily comprehendible and well written in general. 

However, I would appreciate if the authors focused more on the following issues and provided a more critical interpretation of some aspects:

-       What is the clinical need for VNC CT-A (3D reconstructions, VRT required by surgeons was only briefly mentioned without great detail)

Authors: thank you for the comment. This clinical need is of great importance for the surgeon as it can assess pre-operatively an accurate damage overview, especially for those patients with shoulder luxation, by identifying both cartilaginous and bone defects.

Also, 3D reconstruction, allowed by CT, are now often requested by orthopedic surgeons for hip, knee, ankle and elbow as well. 3D reconstructions are needed for a best surgical planning. In this scenario, CT could play a key role representing a one stop one shop exam, allowing both intra-articular evaluation and 3D assessment of the involved joint.

Also, there are organizational issues, with an increasing demand for shoulder, wrist and hip arthrographies even in relatively aged patients (for example to demonstrate the presence of some specific lesions in insurance policy issues). In these cases, CT can successfully replace MRI, being quite accurate and reliable, and without the additional problem of radiation burden that regards young patients.

These consideration will be included in the intro section.

-       I would like to see a critical discussion of sensitivity and specificity of BME-imagines. In my clinical experience, especially specificity is quite low (I am aware of multiple publications stating its feasibility). Possible drawbacks: high bone density, young patient age, etc..

Authors: thank you for the comment. We included the following paragraph in the BME section.

BME detection rate is higher in cases with severe edema in comparison to patients with mild edema and tend to increase in elderly patients because of the relative increase of yellow marrow and thinning of cortical bone [28]. Although specificity could be low, especially in case of young patients with thick cortical bone, or peri-articular bone sclerosis, DECT could play a role when MRI availability is limited or MRI is contraindicated [28].

-       The chapter “metallic artifact reduction” seems a little short. Drawbacks of presented MAR option could be altered image information, altered hyper-/hypodense artifacts at different VMI levels, etc..

Authors: thank you for the comment. We have added the implications of the use of MAR in DECT, for example in the identification of BME.

However it is important to note that MAR have a limited role in DECTA.

-       DECT seems hardly suitable for assessing tendons and ligaments compared to MRI. I would expect a more critical presentation.

Authors: we agree that DECT is slightly less sensitive than MRI in the evaluation of small lesions of tendons and ligaments, but by the injection of contrast material we can increase the conspicuity of the lesions up to 1-2 mm, similar to MRI. We have extended this concept in the manuscript.

- Outlook new imaging techniques? Especially photon-counting CT may provide substantial benefits, e.g. by means of UHR scans without dose penalty (compared to EID detectors and Siemens Somatom Force which requires an additional comb filter for UHR mode). However, BME is not yet supported by PCD software while all 

Authors: thank you for the comment. Further techniques are developing from these results, such as photon-counting CT, with a very high spatial resolution at a relative low dose radiation.

Comments on the Quality of English Language

Minor language issues throughout the manuscript ought to be corrected, possibly be a native speaker (e.g.: Line 25: minor language issue - “map” ought to be plural; Line 35: “jointlesions” ought to be 2 words, please omit the following semicolon.)

Authors: thank you for the comments. We have corrected those parts.

REV 2

The article describes the advanced CT arthrography methods.

The article is very interesting as it explores an area of musculoskeletal radiology that is not widely known even to healht operators working in the field.
There is limited literature on the subject and in particular I think a narrative review providing an overview of the topic would be useful.
The article is well written and well structured. The iconography is excellent. In particular: introduction is detailed, the discussion of the different methods is clear, the conclusions are consistent with the topics addressed, the iconography is excellent. References are appropriate.
I only have a couple of requests for the authors:
1) the type of article should be clarified in the title or at the end of the introduction;

Authors: thank you for the comment. We have added the information at the end of the introduction.

2) in my opinion, the problem of accessibility to these techniques, which is unfortunately scarce, should be discussed much more within the article.

Authors: thank you for the comment. We have added a discussion in the introduction paraghraph.

Reviewer 2 Report

The article describes the advanced CT arthrography methods.

The article is very interesting as it explores an area of musculoskeletal radiology that is not widely known even to healht operators working in the field.
There is limited literature on the subject and in particular I think a narrative review providing an overview of the topic would be useful.
The article is well written and well structured. The iconography is excellent. In particular: introduction is detailed, the discussion of the different methods is clear, the conclusions are consistent with the topics addressed, the iconography is excellent. References are appropriate.
I only have a couple of requests for the authors:
1) the type of article should be clarified in the title or at the end of the introduction;
2) in my opinion, the problem of accessibility to these techniques, which is unfortunately scarce, should be discussed much more within the article.
Thank you.

Author Response

REV 1

The authors aim to provide an overview of the potential DECT-applications for CT arthrography. The article is well structured, easily comprehendible and well written in general. 

However, I would appreciate if the authors focused more on the following issues and provided a more critical interpretation of some aspects:

-       What is the clinical need for VNC CT-A (3D reconstructions, VRT required by surgeons was only briefly mentioned without great detail)

Authors: thank you for the comment. This clinical need is of great importance for the surgeon as it can assess pre-operatively an accurate damage overview, especially for those patients with shoulder luxation, by identifying both cartilaginous and bone defects.

Also, 3D reconstruction, allowed by CT, are now often requested by orthopedic surgeons for hip, knee, ankle and elbow as well. 3D reconstructions are needed for a best surgical planning. In this scenario, CT could play a key role representing a one stop one shop exam, allowing both intra-articular evaluation and 3D assessment of the involved joint.

Also, there are organizational issues, with an increasing demand for shoulder, wrist and hip arthrographies even in relatively aged patients (for example to demonstrate the presence of some specific lesions in insurance policy issues). In these cases, CT can successfully replace MRI, being quite accurate and reliable, and without the additional problem of radiation burden that regards young patients.

These consideration will be included in the intro section.

-       I would like to see a critical discussion of sensitivity and specificity of BME-imagines. In my clinical experience, especially specificity is quite low (I am aware of multiple publications stating its feasibility). Possible drawbacks: high bone density, young patient age, etc..

Authors: thank you for the comment. We included the following paragraph in the BME section.

BME detection rate is higher in cases with severe edema in comparison to patients with mild edema and tend to increase in elderly patients because of the relative increase of yellow marrow and thinning of cortical bone [28]. Although specificity could be low, especially in case of young patients with thick cortical bone, or peri-articular bone sclerosis, DECT could play a role when MRI availability is limited or MRI is contraindicated [28].

-       The chapter “metallic artifact reduction” seems a little short. Drawbacks of presented MAR option could be altered image information, altered hyper-/hypodense artifacts at different VMI levels, etc..

Authors: thank you for the comment. We have added the implications of the use of MAR in DECT, for example in the identification of BME.

However it is important to note that MAR have a limited role in DECTA.

-       DECT seems hardly suitable for assessing tendons and ligaments compared to MRI. I would expect a more critical presentation.

Authors: we agree that DECT is slightly less sensitive than MRI in the evaluation of small lesions of tendons and ligaments, but by the injection of contrast material we can increase the conspicuity of the lesions up to 1-2 mm, similar to MRI. We have extended this concept in the manuscript.

- Outlook new imaging techniques? Especially photon-counting CT may provide substantial benefits, e.g. by means of UHR scans without dose penalty (compared to EID detectors and Siemens Somatom Force which requires an additional comb filter for UHR mode). However, BME is not yet supported by PCD software while all 

Authors: thank you for the comment. Further techniques are developing from these results, such as photon-counting CT, with a very high spatial resolution at a relative low dose radiation.

Comments on the Quality of English Language

Minor language issues throughout the manuscript ought to be corrected, possibly be a native speaker (e.g.: Line 25: minor language issue - “map” ought to be plural; Line 35: “jointlesions” ought to be 2 words, please omit the following semicolon.)

Authors: thank you for the comments. We have corrected those parts.

REV 2

The article describes the advanced CT arthrography methods.

The article is very interesting as it explores an area of musculoskeletal radiology that is not widely known even to healht operators working in the field.
There is limited literature on the subject and in particular I think a narrative review providing an overview of the topic would be useful.
The article is well written and well structured. The iconography is excellent. In particular: introduction is detailed, the discussion of the different methods is clear, the conclusions are consistent with the topics addressed, the iconography is excellent. References are appropriate.
I only have a couple of requests for the authors:
1) the type of article should be clarified in the title or at the end of the introduction;

Authors: thank you for the comment. We have added the information at the end of the introduction.

2) in my opinion, the problem of accessibility to these techniques, which is unfortunately scarce, should be discussed much more within the article.

Authors: thank you for the comment. We have added a discussion in the introduction paraghraph.