Quantitative Characterization of Age-Related Changes in Peripheral Vessels of a Human Palm Using Raster-Scan Optoacoustic Angiography

Round 1

Reviewer 1 Report

Please see attached file.

Comments for author File: Comments.pdf

Author Response

We appreciate referee’ useful comments that helped us to improve, as we believe, the presentation of our results and the overall quality of the manuscript. We have responded to all the comments and have highlighted in yellow the corresponding changes in the manuscript.
Please find attached our response to referee’ specific comments as well as a changes made in the manuscript. We stress that we have implemented all suggestions made by the referees, and resubmit the revised manuscript.

Author Response File: Author Response.pdf

Reviewer 2 Report

 Dear Authors

your extension of the methodology of optonacoustics into the medical field is commendable. Your introduction gives an almost perfect overview of the field and points out relevant work by others. Your sample size is sufficient, though personally I would have liked to see a little more, ~ twice as much. My critique would be that I would like to see uncertainty values included in Table 1. Also, the use of p<0.05 as a discriminator is always a little 'too optimistic for me'.  I chased up on the history of that value and it was defined by Fisher himself almost 100 years ago and he regretted that it became such a standard, as the statistical correlation is rather on the optimistic side. However, it has since become the standard of evaluation in a lot of fields. I would however suggest that for further investigations to try to implement a more stringent benchmark, like the Fisher Exact Test when applicable. You are already heading in the right direction using the Duncan's test method. Setup and data, and data analysis are well depicted. The conclusion should summarize again and mention some of the values which you deduced.  

I therefore recommend the article for publication, subject to a manifold of 'minor corrections', mainly of grammatical nature. There were quite a few and for the next publication, I would recommend you use a editor's service to avoid that manifold of minor mistakes. 

As for the citations, I noticed the journal names only showed the first word in Capital, like for the heading. I am not a fan of that, as all words within a journal name should be in large, e.g., 'Cardiovascular Diabetology' ... Anyhow that may be the MDPI layout policy at the moment. 

Here is the long list of corrections that need to be applied:

Often you refer to e.g. paper [23] or so in the citation, I would name here the main author and the et al., .So, e.g., 'in the paper by Smith et al. [23]'

Sentences: length, and number of branches /add comma
Sentence: collaterals, and suppression of vascular reactivity /add comma
Sentence:  described, and the prognostic value for the development /add comma
Sentence: or vasospasm, decreased circulation in the periphery, Here: remove comma and put 'and' instead
Sentence:  leading to late diagnosis   change to: leading to a late diagnosis
Sentence: increased vessel length demonstrated using capillaroscopy    change to increased vessel length were demonstrated using capillaroscopy
Sentence: for processing three-dimensional OA images based on a graph representation of vascular net. for processing three dimensional OA images based on a graph representation of the vascular net.
Sentence:  length of the vessels and the branching of the  insert comma before and
Sentence: interface between US detector' change to interface between the US detector
Sentence: The first stage of the OA images analysis'  change to The first stage of the OA image analysis
Sentence; consiquently' change to consequently
Sentence: At the second stage' change to In the second stage
Sentence: total length of all vessels change to 'A total length of all vessels'
Sentence: rib average change' to 'average rib'
Sentence: different age groups the total  insert comma: different age groups, the total
Sentence:  In addition, for each image the blood content' insert comma after image,
Sentence: age groups was assessed using One-Way ANOVA  change was to 'were'
Sentence change to: In accordance with the modern anatomy paradigm, normal skin microcirculation is organized in two plexuses parallel to the skin’s surface
Sentence change to: In superficial layers, blood content demonstrates a high correlation with age group: group 1 demonstrates low blood content at typical depths up to 300 µm as compared to lower plexus, while group 2 demonstrates the comparable value of blood content for both superficial layers and lower plexus.
Sentence change to: The ratio of blood content at two characteristic depths, shown with dashed lines in Fig. 3d, demonstrated statistically significant differences between the three age groups and increase with age (Fig.3e).
Sentence: White dashes change to White dashed line
Sentence change to: Vessel amount per volume unit and vessel average length decrease with age, whereas the blood content in the whole volume increases because the vessel’s diameter becomes larger with age (Fig.2c).
Sentence change to:L Various parameters were obtained from the OA angiographic images and averaged over each of the three age groups.
Sentence change to: he corresponding p-values (probability values) for parameters that statistically significant (p<0.05) are shown in Table 2.
Sentences change to: A decrease with increasing age was revealed for the following parameters: the total number of branches, the total number of nodes, the vessel density, the total length of all vessels, and the average length of one vessel. The average rib length varied insignificantly.
Sentence: in average change to 'on average'
Sentence change to: In our paper, the vessel density as well as the vessel amount per volume unit were calculated in all imaging volumes up to 2 mm and decreased with age (Fig. 5c), but were not statistically significant.
Sentences: Fig. 3d demonstrates that the major difference in blood content is observed at depths up to 400 µm. Moreover, since the vessel sizes are significantly larger in Group 3 as compared to Groups 1 and 2 (Fig. 2,4), one can expect a consistency of our results with OCT observations [21]
Sentence: It is important to note that a gradual decrease in vessel length and branching with age, revealed in our work, accompanies an increase in the OA signal level. Loss of superficial capillary loops, an increase in the transparency of the skin, and the availability of deep vessels for observation accompanying the aging process [34], inhibition of blood flow, and stasis [35] may be the reasons for the revealed increase in the OA signal level with age.
Sentence: ratio of blood change to 'the ration of blood'
Sentence: Remove comma before and in last sentence: pathological 'changes and predict the probable course of the disease.'

 

 

 

 

Author Response

We appreciate referee’ useful comments that helped us to improve, as we believe, the presentation of our results and the overall quality of the manuscript. We have responded to all the comments and have highlighted in yellow the corresponding changes in the manuscript.
Please find attached our response to referee’ specific comments as well as a changes made in the manuscript. We stress that we have implemented all suggestions made by the referees, and resubmit the revised manuscript

Author Response File: Author Response.pdf

Reviewer 3 Report

The manuscript entitled “Quantitative characteristics of age-related changes in peripheral vessels from in vivo optoacoustic angiographic images” reports a method to investigate the vascular changes in the skin which is based on optoacoustic angiography. Finally, based on the data obtained several parameters were used to characterize the skin and show the changes caused due to advancing age.

The method presented is of great interest, however some issues need to be addressed.

The authors have used for their study volunteers with Caucasian skin (Fitzpatrick type II-III). Do they think the method could have limitation if the person investigate would have a Fitzpatrick type IV or higher?

Did the authors tried to perform measurements for the fingers? For the Raynaud's syndrome the problem is locate in same cases at the fingers.

In fig 3 the axis in the panel e are hard to read.

For fig 2, 3, 4 and table 1 were are presented one example for each age group the author should rephrase it to make it clearer for the readers.

Some of the p values reported in table 2 are not the same with the one reported in fig 5 although the same parameters are represented.

For example, for Vessel intensity FN, in figure 5 all conditions are statistically different. However, in table 2 condition 2 and 3 are not different.

The results should be discussed in more details.

Finally, based on the results significant difference can be reported only one comparing the first age group with the third one. This should be stated in clear in the manuscript.

Author Response

We appreciate referee’ useful comments that helped us to improve, as we believe, the presentation of our results and the overall quality of the manuscript. We have responded to all the comments and have highlighted in yellow the corresponding changes in the manuscript.
Please find attached our response to referee’ specific comments as well as a changes made in the manuscript. We stress that we have implemented all suggestions made by the referees, and resubmit the revised manuscript

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

All my concerns have been addressed. This paper can be accepted for publication

Reviewer 3 Report

The manuscript improved and can be accepted in the present form.