Long COVID in Young Patients: Impact on Lung Volume Evaluated Using Multidetector CT

Round 1

Reviewer 1 Report

Manuscript: Long COVID in young patients: impact on lung volume evaluated using MDCT

Overview: In the current paper, authors analyzed lung volumes through a quantitative analysis on Chest CT scans in young patients (18-40 years) after being diagnosed with COVID-19.

I have the following suggestions in order to improve the value of the manuscript:

1) Major observations:

a)     Once I start reading the manuscript, I was eager to identify possible explanations regarding the findings. Even though, there was a lesser lung volume based on quantitative analysis on Chest CT scans in patients recovering from COVID-19 which is not unexpected. It should have a better impact if authors analyzed Lung Function (using lung volumes and lung diffusion). The justification of this suggestion is that measuring lung volumes is currently the gold standard. Therefore, must need to be incorporated to strengthen the findings, otherwise may not have a clinical impact.

b)    Another major point is to know if the authors analysed the results according to the severity and the need of supplementary oxygen. This point is crucial since several documents have been published highlighting this hypothesis. If we don’t further discuss who were the patients based on severity, How or where the results should be applied?

c)     Authors must clarify the possible bias related to the technical procedure since majority of imaging studies are operator dependent. Does the CT scan was obtained at full inspiration / expiration?

d)    Also, since using AI to determine any specific variable depends on gold-standard reference, this study lacks the support with pulmonary function tests.

e)     Also, and I quote “Right lobe volume” and “left lobe volume” does represent an specific lobe? Or is the right and left lung volumes respectively.

2) Minor observations

a) Adding a table where the authors describe the between groups quantitative measurement lung volumes differences should be added.

b) Authors should analyze if the factors considered affecting lung volumes are truly risk factors.

Moderate editing of english language

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

Bellini et al. retrospectively investigate the lung volume of Sar-Cov-2 infected and naive populations by CT scan reconstruction technique. The design is rigorous, there is a significantly different between the two groups. However, there was only one method to detect the parameters, which is suggested to add more methods to confirm. 

Major points:

1. The time period covers more various seasons in the control group (4 seasons) than in the covid-19 group (2 seasons). Although it was difficult to recruit the same-year population without covid-19, it is suggested to limit the same months period to different years. 

2. Since the golden standard of lung capacity is the parameters from lung function tests or spirometry detection, such as FVC, and TLC. So it should also collect patients' LFT data to adjust the CT image calculation. Since the authors also mentioned the different brands of CT machines in the study. 

3. More pathophysiology reasons or explanations for the lung volume change phenomenon should be researched. Such as if the blood inflammation cytokine was different in the two populations. 

Minor point:

The thickness of CT scanning should be clarified. Since different reconstruction thicknesses will cause fluctuations in the volume calculation.

In all, the study is interesting and defines the difference between the infected and non-infected populations of SAR-Cov-2. However, in the current stage, the manuscript did not reach the publishing standard.  

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

None

Minor edits.

Author Response

We would like to thank the reviewer for the careful reading of the manuscript and the constructive remarks.

The manuscript has now been revised and expanded following reviewer’s comments.