| Objective With the development of high-resolution CT technology,lung volume scanning can be quickly and easily achieved,and based on the "digital lung" lung structure measurement tool,lung volume(m L),lung density(HU),pulmonary vascularity,and emphysema quantitative values can be obtained,which can better display the structural changes of normal and abnormal lung tissues.This study investigates the differences in lung structure between healthy people in high altitude and plain areas by quantitative CT measurements and the differences in lung structure changes between COPD patients and healthy people in high and low altitude areas,and provides quantitative information on digital lung structure for healthy people and COPD patients in high altitude areas.Methods The data and methods of this study include two parts(1)Part I: 1)Healthy people at different altitudes: 324 cases of healthy people at high altitudes who met the inclusion and exclusion criteria were retrospectively collected,including 138 cases of men and 186 cases of women,and were divided into 4 groups according to age and sex(Female group: <50 years and ≥50 years;Male group: <50 years and ≥50 years);2)269 cases of healthy people at low altitudes who met the inclusion and exclusion criteria were retrospectively collected,including 119 cases of men and 150 cases of women,and were divided into 4 groups according to age and sex.Among them,119 cases were males and 150 cases were females,which were divided into 4 groups according to age and gender(Female group: <50 years and ≥50 years;Male group: <50 years and ≥50 years;3)The high-altitude and low-altitude healthy populations were obtained according to age matching for 269 cases,among which 119 cases were males and 150 cases were females;they were divided into 2 groups(highaltitude group and low-altitude group)according to altitude.The matched high and low-altitude groups were grouped according to age and sex(<50years old group,≥50 years old group,and male and female groups).(2)Part II: 1)COPD population at different altitudes: 108 cases of COPD population at high altitude meeting the inclusion and exclusion criteria were retrospectively collected,including 79 cases of GOLD grade 1/2 and 29 cases of GOLD grade 3/4,and divided into 2 groups(GOLD1/2 and GOLD3/4)according to GOLD classification.2)COPD populations at high and low altitudes were obtained by matching according to GOLD classification The population was 62 cases respectively,including 41 cases of GOLD1/2 grade and 21 cases of GOLD3/4 grade.The patients were divided into 2 groups(high and low altitude groups for GOLD1/2;high and low altitude groups for GOLD3/4)according to the same grading of different altitudes.3)Seventy-two cases of the high-altitude healthy population and COPD population were obtained by matching according to age and BMI,respectively,and grouped(healthy population group and COPD population group).The chest CT images of all included patients were analyzed by quantitative CT analysis of the obtained images using the Dexin-FACT software of the Digital Lung Measurement Platform to measure the values of quantitative CT measurements related to COPD.Data from each group were compared and conformed to a normal distribution using the independent samples t-test and skewed distribution using the Mann-Whitney U test,with differences considered statistically significant at P < 0.05.Results: Part I results from(1)High altitude:(1)same sex different age group: no statistically significant differences in pulmonary vascularity(except some lobes),lung volume,lung density,LAA%-950 in the <50 years and ≥50 years groups in males and females(P > 0.05).(2)Different sexes in the same age group: statistically significant differences in pulmonary vascularity and lung volume(P < 0.05)and no statistically significant differences in lung density,LAA%-950(P > 0.05)but statistically significant differences in LAA%-950 in some lung lobes(P >0.05)in the <50 years and ≥50 years male and female groups.2)Low altitude group:(1)same sex different age group: statistically significant(P <0.05)differences in pulmonary vascular partial lobes between men and women in the <50 years and ≥50 years groups;but no statistically significant(P > 0.05)differences in lung volume,lung density,LAA%-950.(2)Different sexes in the same age group: the differences in pulmonary vascularity,lung density,lung volume,and LAA%-950 were statistically significant in the male and female groups at <50 and ≥50 years of age(P <0.05)but not in the lung density part of the lung lobes at <50 years of age.(3)Comparison of quantitative CT measurements between high and low altitude groups:(1)Different altitudes in the same age group(<50 years)Same-sex:men: statistically significant differences in pulmonary vascularity,lung density,LAA%-950(P < 0.05)but not in lung volume(P > 0.05);women:statistically significant differences in pulmonary vascularity(P < 0.05)but not in lung density,LAA%-950(P > 0.05),lung volume,LAA%-950 differences were not statistically significant(P>0.05).(2)Differences in the same age group(≥50 years)at different altitudes Same sex: men: statistically significant(P < 0.05)but not statistically significant(P > 0.05)differences in pulmonary vascularity,lung density,(right middle lobe,left upper lobe,left lower lobe)LAA%-950;women: statistically significant(P > 0.05)differences in pulmonary vascularity,(whole lung,right upper lobe,left upper lobe,left lower lobe)lung volume The difference was statistically significant(P < 0.05)but the difference in lung density,LAA%-950 was not statistically significant(P > 0.05).Part II results(1)Different classifications of GOLD in COPD at high altitude: the differences in lung density were statistically significant(P< 0.05)except for the middle lobe of the right lung and the upper lobe of the left lung,and the GOLD1/2 group was higher than the GOLD3/4 group;the differences in pulmonary vascularity,lung volume,LAA%-950 were statistically significant(P < 0.05)except for some lung lobes,and the GOLD3/4 group was higher than the GOLD1/2 group.(2)Quantitative CT measures between the high-altitude healthy population group and the COPD population group: pulmonary vascularity,lung volume,and LAA%-950 were lower in the healthy population group than in the COPD population group,and the differences were statistically significant(P < 0.05).Lung density was higher in the healthy population group than in the COPD population group,except for the upper lobe of the right lung,and the difference between the two groups was not statistically significant(P>0.05).(3)Classification of COPD at different altitudes:(1)GOLD1/2 grade:pulmonary vascularity and lung volume were higher in the high altitude group than in the low altitude group,but the difference between the two groups was not statistically significant(P>0.05).Lung density was higher in the high-altitude group than in the low-altitude group,and the difference between the two groups was statistically significant(P < 0.05).LAA%-950 was significantly lower in the high-altitude group than in the low-altitude group,and the difference between the two groups was statistically significant(P < 0.05).(2)GOLD grade 3/4: pulmonary vascularity and lung volume were slightly lower in the high-altitude group than in the lowaltitude group,but the difference between the two groups was not statistically significant(P > 0.05).Lung density was higher in the highaltitude group than in the low-altitude group,and the difference was statistically significant(P < 0.05).LAA%-950 was significantly higher in the high-altitude group than in the low-altitude group,and the difference was statistically significant(P < 0.05).Conclusions(1)Automatic computer-aided measurements based on the lung tissue structure can be obtained quickly and easily and applied to assess lung diseases.(2)Lung volumes were approximately the same in high and low altitudes in the healthy population,but pulmonary vascularity and lung density were higher in the high-altitude group than in the low-altitude group,suggesting that there are more pulmonary vessels in the healthy population at high altitude than in the low altitude group.(3)With the increase of GOLD grading in COPD patients,lung vascularity,volume,and emphysema values were higher in COPD grade 3/4 patients than in COPD grade 1/2 patients,suggesting that chest CT measurement index can be used in grading COPD patients.(4)Pulmonary vascularity was greater in COPD grade 1/2 patients at high altitude than in patients at low altitude,but there was no difference in pulmonary vascularity between the two groups in COPD grade 3/4,suggesting that chest CT measurement indexes may overestimate the grading of early COPD patients in highland areas. |
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