Validity and Absolute Reliability of Axial Vertebral Rotation Measurements in Thoracic and Lumbar Vertebrae

Round 1

Reviewer 1 Report

A very interesting study with a good design and analysis of the reasons for the difference in the results of the validity and reliability of the study of the thoracic and lumbar spine.

At the same time, the authors' opinion on possible ways to increase validity and reliability using software or methodological approaches is interesting.

It is advisable to describe in more detail the features of the software. Although detailed elsewhere (Hurtado-Aviles, J .; Roca-González, J .; Kurochka, KS; Sanz-Mengibar, JM; Santonja-Medina, F. Developing of a 372 Mathematical Model to Perform Measurements of Axial Vertebral Rotation on Computer-Aided and Automated Diagnosis 373 S_y_s_t_e_m_s _, _ _U_s_i_n_g_ _R_a_i_m_o_n_d_i_'s_ _M_e_t_h_o_d _._ _Radiol. Res. 1–9. research.

What could be the reason for choosing the wrong level of measurement of the vertebral bodies?

In general, the study meets the requirements of the journal, has a high scientific level, value for scientific and practical use in vertebrology. The research methods are described in sufficient detail and correspond to the objectives of the research. The results obtained are consistent with the objectives of the study. The conclusions are substantiated and based on the results obtained.

The manuscript does not need revision and reduction. Additional data on ways to improve the accuracy of diagnostics and software features can be entered at the discretion of the authors.

Information for discussion.

It is desirable to clarify the terminology regarding torsion and rotation. In our understanding, torsion is a pathological deformity of a vertebra with a fixed rotation position in the axial plane. Rotation is the normal functional mobility of the vertebrae relative to each other in the axial plane.

Author Response

Author's Reply to the Review Report (Reviewer 1)

Comments and Suggestions for Authors

A very interesting study with a good design and analysis of the reasons for the difference in the results of the validity and reliability of the study of the thoracic and lumbar spine.

At the same time, the authors' opinion on possible ways to increase validity and reliability using software or methodological approaches is interesting.

First, we would like to thank you for your comments and for allowing us to address the issues you raise to improve the manuscript’s quality. We will provide a point-by-point response to your comments and objections and indicate the modifications we propose to the manuscript to incorporate your comments.

The possibility of increasing the vertebra’s size with the mouse’s scroll wheel allows the correct determination of the reference points. Frequently, determining the width of the vertebra is difficult due to the overlap of structures, particularly in the dorsal vertebrae, and focusing on the width of the adjacent vertebrae can make that easier. (We have added this information in the Discussion section.)

The other less reliable potential source of error is the determination of the most rotated vertebra, which is avoided by measuring the vertebrae adjacent (cranial and caudal) to the one most rotated suspected. Sometimes we will be surprised to find that the vertebra we thought was more rotated is not.

It is advisable to describe in more detail the features of the software. Although detailed elsewhere (Hurtado-Aviles, J .; Roca-González, J .; Kurochka, KS; Sanz-Mengibar, JM; Santonja-Medina, F. Developing of a Mathematical Model to Perform Measurements of Axial Vertebral Rotation on Computer-Aided and Automated Diagnosis Systems,  Using Raimondi's Method . Radiol. Res. 1–9. Research).

We have added in different M&M paragraphs the description of what we use for software development and the equation used.

The software was developed in C++ under the Microsoft Visual Studio 2019 development environment and used the OpenCV 3.4.10 artificial vision libraries and the DCMTK libraries, from OFFIS - Institute for Information Technology, to operate with DICOM (Digital Imaging and Communication On Medicine) files.

The software incorporates additional tools, such as the ability to zoom in on regions of interest and to vary the contrast (fractional difference in optical density of the brightness between two regions of an image) of the digitalised X-ray image.

To perform the AVR calculation, the observer opens the X-ray image and selects the most rotated vertebra (in case of doubt among two vertebrae, the operator measured both). The observer zooms in on the vertebra and selects with a mouse click the two closest points of the vertebral body's lateral faces, and the two opposite sides of the shadow of the pedicle rotated towards the centre of the vertebra in the anteroposterior projection (Fig. 1).  Based on these points’ position, the software calculates the vertebral body’s width (D) and the distance from the centre of the pedicle to the side of the vertebral body (d). From their relationship, it applies Raimondi’s method according to the following equation:

AVR=(20.22483-330.5077(D/d)+33.46082(D/d)^2)/(1-3.93825(D/d)-1.322272(D/d)^2 )

What could be the reason for choosing the wrong level of measurement of the vertebral bodies?

The main reason for incorrect level determination and worse reliability is that the vertebra to be measured (the one with the highest torsion) is often determined with the naked eye and measured. We measure at least the two most twisted vertebrae at the apex of the scoliotic curve (in case of doubt three) and use the value of the vertebra with the highest degree of twisting. The software facilitates the measurement by enlarging the vertebra’s size with the mouse wheel and because it calculates the degree of torsion automatically after determining the four reference points that are precise for this method.

In general, the study meets the requirements of the journal, has a high scientific level, value for scientific and practical use in vertebrology. The research methods are described in sufficient detail and correspond to the objectives of the research. The results obtained are consistent with the objectives of the study. The conclusions are substantiated and based on the results obtained.

We appreciate the positive assessment of our research. Thank you very much.

The manuscript does not need revision and reduction. Additional data on ways to improve the accuracy of diagnostics and software features can be entered at the discretion of the authors.

As mentioned in your previous comments, we have incorporated some of the aspects you mention into the manuscript’s text, and we think it adds to the manuscript’s quality. Thank you very much.

Information for discussion.

It is desirable to clarify the terminology regarding torsion and rotation. In our understanding, torsion is a pathological deformity of a vertebra with a fixed rotation position in the axial plane. Rotation is the normal functional mobility of the vertebrae relative to each other in the axial plane.

We fully agree with your comment. The problem is that in the literature, the term “vertebral rotation” has been the one used in most of the articles consulted (AVR, axial vertebral rotation), and to avoid creating misunderstanding to the readers, we have employed the same terminology. Nevertheless, we have added your reflection in the Discussion section, and we mentioned this in the introduction.

Stokes IA. Three-dimensional terminology of spinal deformity. A report presented to the Scoliosis Research Society by the Scoliosis Research Society Working Group on 3-D terminology of spinal deformity. Spine (Phila Pa 1976). 1994 Jan 15;19(2):236-48.

Thank you again for the constructive criticism of our manuscript and for your time.

Reviewer 2 Report

An interesting paper where the authors have evaluated the validity and absolute reliability of thoracic and lumbar vertebrae AVR measurements. Some comments to the authors are given:

1- No need to end the article title with a dot.

2- The introduction part is very short. The authors must mention the previous work and what they have added. This will contribute to the novelty of the research.

3- The caption of figure 1 is not appropriate. Please check it. I think some of the surrounding text has been attached with the figure caption.

4- The captions of figures 2, 3, and 4 are given above the figures. The figure caption should be below the figure. 

5- The authors should restate what they have done at the beginning of the conclusion part. Also, I suggest rewriting the main conclusions. 

Author Response

Author's Reply to the Review Report (Reviewer 2)

Comments and Suggestions for Authors

An interesting paper where the authors have evaluated the validity and absolute reliability of thoracic and lumbar vertebrae AVR measurements. Some comments to the authors are given:

We want to thank you for your comments to improve the manuscript’s quality. We will respond point by point and indicate the modifications we propose to incorporate your comments. Thank you.

• No need to end the article title with a dot.

As you suggest, we have removed the dot from the title.

• The introduction part is very short. The authors must mention the previous work and what they have added. This will contribute to the novelty of the research.

We have added to the Introduction section important definitions, information on other measurement systems, and, as you indicate, information on a recently accepted paper (in press) in which we compare software-assisted and conventional measurements.

• The caption of figure 1 is not appropriate. Please check it. I think some of the surrounding text has been attached with the figure caption.

We had included the description of measurement’s implementation in the caption, but we agree with you to modify the figure caption and change the narrative to M&M.

• The captions of figures 2, 3, and 4 are given above the figures. The figure caption should be below the figure.

We have corrected the error. Thank you.

• The authors should restate what they have done at the beginning of the conclusion part. Also, I suggest rewriting the main conclusions.

As you indicate, we have modified the conclusions, starting with the highlights of our research:

We conclude that software assisted AVR measurements in frontal spine X-rays of patients with scoliosis at the lumbar level are more accurate and valid than at the thoracic level. AVR measurements of the thoracic vertebrae show a mean bias error of 3.6 times higher and very similar reliability (1.88° vs 1.83°) to the AVR of lumbar vertebrae measurements in an assessment with absolute reliability and validity criteria. Despite this difference, at both levels (thoracic and lumbar), the degree of inter-rater agreement with the software TraumaMeter v.873 was almost perfect.

Thank you again for the constructive criticism of our manuscript and for your time.