Ultrasound Elastography: Basic Principles and Examples of Clinical Applications with Artificial Intelligence—A Review
, Natascha Claudia D'Amico 2, Giulia Maria Danesini 1, Chiara Foschini 1, Giancarlo Oliva 3, Carlo Martinenghi 4 and Michaela Cellina 3,*
Round 1
Reviewer 1 Report
The manuscript presents a short outline of the basic physical principles involved in ultrasound elastography. There are many reviews and book that seems to dive deeper offering a better understanding of the basic physical principles that any researcher and end user of elastography should know. Some of them are actually in the list of reference. Consequently, what is the utility of this paper?
Just some examples:
- Bamber et al. EFSUMB Guidelines and Recommendations on the Clinical Use of Ultrasound Elastography. Part 1: Basic Principles and Technology. Ultraschall Med. 2013, 34, 169-184.
- Cosgrove et al. EFSUMB guidelines and recommendations on the clinical use of ultrasound elastography. Part 2: Clinical applications. Ultraschall Med. 2013, 34, 238–253.
- Sigrist et al. Ultrasound elastography: a review of techniques and clinical applications. Theranostics 2018, 7, 5, 1303.
- Nenadic et al. Ultrasound elastography for biomedical applications and medicine. Wiley Series in Acoustics, Noise and Vibration. 2019. Joh Willey & Sons Ltd.
Some spotted errors:
Most equations show comas and dots wrongly placed. Also, most of them do not have references.
Line 35: Where it says ‘paragraph’ it should say something different, like section or subsection.
Lines 42-44: The promised section with AI applications in USE is missing.
Line 96: Tension is normally reserved for a pulling distributed force over an area that yields to a elongation deformation, for a more general term, I would recommend to use "stress".
Line 127: Equation 2? There is no shear wave velocity in equation 2.
Equation 12: This is mistaken, E should be replaced by M, the p-wave modulus, which for soft tissue, is in the order of GPa. E is smaller, usually by 6 order of magnitude.
Line 188: It is not E, is M.
Line 196: Careful. That is correct for shear waves. For p waves wave velocity varies very little in soft tissue.
Line 265: Strain Imaging does not provide a quantitative result but a qualitative one.
Lines 278 – 321: Excessively long figure caption. Most of the it should go into the body text of the manuscript.
Author Response
The authors thank the reviewer for the work and precious suggestions.
We performed extensive changes of the manuscript to fit the reviewer's indication and further improve the quality of our article.
The manuscript presents a short outline of the basic physical principles involved in ultrasound elastography. There are many reviews and book that seems to dive deeper offering a better understanding of the basic physical principles that any researcher and end user of elastography should know. Some of them are actually in the list of reference. Consequently, what is the utility of this paper?
Just some examples:
- Bamber et al. EFSUMB Guidelines and Recommendations on the Clinical Use of Ultrasound Elastography. Part 1: Basic Principles and Technology. Ultraschall Med. 2013, 34, 169-184.
- Cosgrove et al. EFSUMB guidelines and recommendations on the clinical use of ultrasound elastography. Part 2: Clinical applications. Ultraschall Med. 2013, 34, 238–253.
- Sigrist et al. Ultrasound elastography: a review of techniques and clinical applications. Theranostics 2018, 7, 5, 1303.
-Nenadic et al. Ultrasound elastography for biomedical applications and medicine. Wiley Series in Acoustics, Noise and Vibration. 2019. Joh Willey & Sons Ltd.
We thank the reviewer for this consideration. We are aware that other work on this topic are available, and several are suggested in the text. However, most are mainly written by engineers for engineers, while others, including the eminent review by Sigrist et al. which we use as a reference as well, presents only the final equations assuming already a basic knowledge of some physical principles.
In this new version of the manuscript we provide a complete step-by-step explanation of the equations and starting from the basic definition of elasticity.
Some spotted errors:
Most equations show comas and dots wrongly placed. Also, most of them do not have references.
We've fixed errors and added references.
We revised and corrected all the equation, as suggested.
Line 35: Where it says ‘paragraph’ it should say something different, like section or subsection.
Thank you for the comment, we replaced this term.
Lines 42-44: The promised section with AI applications in USE is missing.
We apologize for the mistake, this sentence remained from a previous version of the manuscrit. We already planned to expand the work and therefore, based on your suggestions, we extensively revised the manuscript by adding a section on clinical applications.
Line 96: Tension is normally reserved for a pulling distributed force over an area that yields to a elongation deformation, for a more general term, I would recommend to use "stress".
Thank you for the comment, we replaced the term accordingly.
Line 127: Equation 2? There is no shear wave velocity in equation 2.
We apologize for the mistake, and corrected with the correct equation.
Equation 12: This is mistaken, E should be replaced by M, the p-wave modulus, which for soft tissue, is in the order of GPa. E is smaller, usually by 6 order of magnitude.
Line 188: It is not E, is M.
We apologize for the error. However, we introduced the parameter (K) according to the vast majority of authors which derive the velocity of the longitudinal waves from the bulk modulus (Shiina et al., Sigrist et al., Wells et al.). We know that in geophysical models the module M is used to describe pressure waves propagation. However, using M would require introducing further concepts like the 1^ Lamé constant and other equations, which is beyond the scope of our text. Sigrist et al., which was suggested by the reviewer in the beginning, find K a suitable approximation.
Line 196: Careful. That is correct for shear waves. For p waves wave velocity varies very little in soft tissue.
We apologize for the mistake and corrected it
Line 265: Strain Imaging does not provide a quantitative result but a qualitative one.
We apologize for the mistake and corrected it.
Lines 278 – 321: Excessively long figure caption. Most of the it should go into the body text of the manuscript.
We tried to reformulate the caption and reduce their lenght.
Thank you very much
Best regards
The authors
Reviewer 2 Report
In the paper, the authors presented the physical basis of elastography. They acquainted the reader with the basic physical laws and presented various techniques and types of elastography. For a review on the use of elastography in medicine, there are too few citations from the real application of this solution. The authors in their work completely omitted and underestimated the important topic of elastography in intestinal diseases.
Currently, this is an area in gastroenterology that encounters problems regarding the use of elastography for diagnosis and tracking the therapeutic progress of patients. It has been proven in some articles that despite good results, elastography methods cannot be successfully used in diagnostics because protocols are missing.
1. Why did you omit the use of elastography in inflammatory bowel diseases?
At a time when this is a serious diagnostic problem, it is necessary to quote those articles that perfectly address the problem of using elastography in inflammatory bowel diseases in your article (https://www.mdpi.com/2075-4418/12/9/2070/htm, https://www.mdpi.com/2075-4418/11/9/1609/htm). Complete the introduction in which you do not mention the intestines as an organ for diagnosis.
The rest of the article is flawless. Only the long descriptions under the figures draw attention. Is it not possible to transfer extended texts from the descriptions to the main text of the article?
What do you have to do:
1. Cite 2 articles on the use of elastography in the diagnosis of inflammatory bowel diseases.
2. Complete the part of the introduction about the intestines.
3. Consider shortening or moving the text of dispute Figures to the main text.
Author Response
The authors thank the reviewer for the work, the positive comments and the precious suggestions.
We executed an extensive revision of the manuscript and modified it according to the reviewer's commment.
In the paper, the authors presented the physical basis of elastography. They acquainted the reader with the basic physical laws and presented various techniques and types of elastography. For a review on the use of elastography in medicine, there are too few citations from the real application of this solution. The authors in their work completely omitted and underestimated the important topic of elastography in intestinal diseases.
Currently, this is an area in gastroenterology that encounters problems regarding the use of elastography for diagnosis and tracking the therapeutic progress of patients. It has been proven in some articles that despite good results, elastography methods cannot be successfully used in diagnostics because protocols are missing.
1. Why did you omit the use of elastography in inflammatory bowel diseases?
At a time when this is a serious diagnostic problem, it is necessary to quote those articles that perfectly address the problem of using elastography in inflammatory bowel diseases in your article (https://www.mdpi.com/2075-4418/12/9/2070/htm, https://www.mdpi.com/2075-4418/11/9/1609/htm). Complete the introduction in which you do not mention the intestines as an organ for diagnosis.
The rest of the article is flawless. Only the long descriptions under the figures draw attention. Is it not possible to transfer extended texts from the descriptions to the main text of the article?
What do you have to do:
1. Cite 2 articles on the use of elastography in the diagnosis of inflammatory bowel diseases.
2. Complete the part of the introduction about the intestines.
3. Consider shortening or moving the text of dispute Figures to the main text.
We widen the manuscript by inserting a whole section on the clinical applications of US elastography in the clinical practice for distinct anatomical district and we inserted a section on the inflammatory bowel diasese as suggested.
We inserted the recommended references, as well.
We reformulated the captions, shortening them when possible.
Thank you very much
The authors
Round 2
Reviewer 2 Report
Thank you for following the suggestions. The work enriched with an additional subchapter is currently a very good review of the clinical application of elastography in diagnostics. It is a major contribution to this still developing field.
