High Resolution CT Airway Reconstruction Parameters And Its Application In Evaluation Of Small Airway Structure Changes Caused By Carbon Black Exposure

Object:1.Explore the best imaging parameters to assess changes in airway structure,setting the reference value range;2.Analyze the effects of carbon black exposure and exposure concentration on airway structure;3.To explore the correlation between changes in lung structure and function of workers exposed to carbon black,and their application in studying early health damage in exposed populations.Methods:1.Examing the general population by High resolution CT,using image post-processing software to measure paramters of the right upper lobe bronchus tip,right lower lobe bronchial lateral basal segment,left upper lobe bronchial superior branch apical segment and left lower lobe bronchial lateral basal.The airway parameters of level 6 and level 9 of the segment are reconstructed,and a method for measuring small airways is established.Evaluate the reference value range of the general population,and use a linear mixed-effects model to adjust the age,gender,overweight,smoking status,number of packs,lung segment,and reconstruction method to analyze the influencing factors of airway parameters.2.High resolution CT examination was performed on workers exposed to carbon black,and combined with image post-processing software,the right upper lobe bronchus tip,right lower lobe bronchus lateral basal segment,left upper lobe bronchus superior branch apical segment and left lower lobe bronchial lateral basal were measured which contained level 6 and level 9.Using a linear mixed-effects model,adjust age,gender,overweight,smoking status,number of packs,lung segment and reconstruction method,analyze the effect of carbon black exposure on airway parameters and the relationship between airway parameters and lung function indicators.3.Sputum induction was performed on the research subjects and stored using Saccomano solution;slides were prepared after centrifugation and DBPS cleaning,and the slides were quickly stained with Diff-qiuk solution.Finally,image J software was used to photograph the sputum smears of the research subjects and quantitative analysis of charcoal particles in macrophages.Test the lung function of the study subjects.4.The relationship between carbon black exposure dose and small airway changes,as well as small airway changes and lung function measurement parameters were analyzed to verify the effectiveness of biomarkers.Results:1.Through the analysis of the small airway parameters of High resolution CT reconstruction,the airway wall area percentage was selected as the biomarker parameter of airway changes.The sixth-grade of airway wall area percentage in the Left B1+2 to carina is（53.01±13.35）%,Left B9 to carina is（50.44±12.98）%,Right B1 to carina is（52.73±12.22）%,and Right B9 to carina is（52.93±11.85）%.The nineth-grade of airway wall area percentage in the Left B1+2 to carina is（44.08±14.66）%,Left B9 to carina is（42.44±15.89）%,Right B1 to carina is（46.51±14.03）%,and Right B9 to carina is（43.54±15.87）%.The airway wall area percentage of the overweight or obese people to the total trachea area is higher than that of the normal people（all P value<0.05）.2.Carbon black exposure caused thickening of the tracheal wall,reduced tracheal lumen,and unchanged total tracheal area.Compared with controled people,the 6^th WA%of exposure workers increased by 8.60（P<0.0001）;9^th WA%increased by 7.31（P<0.003）.There was a positive correlation between CCAM of macrophage carbon particles in sputum and 6^th WA%and 9^th WA%.For every 10%increase in macrophage carbon content,6^th WA%increased by 4.08（P=0.001）;9^th WA%increased by 3.88（P=0.03）.Airway parameter WA%was negatively correlated with lung function parameters FEV1,FEV1/FVC.For every unit increase in the sixth-grade WA%,FEV1 decreased by 20m L（P<0.0001）;FEV1/FVC decreased by 0.14%（P=0.001）.For each unit of WA%increase in nineth-grade,FEV1 decreased by 11 mL（P<0.0001）;FEV1/FVC decreased by 0.12%（P=0.0002）.Macrophage carbon content in sputum was negatively correlated with FEV1and FVC.For every 10%increase in macrophage carbon content,FEV1 decreased by 210m L（P<0.0004）;FVC decreased by 260 mL（P<0.0001）.The decrease in FEV1 causedby carbon black exposure is mediated by tracheal wall thickening.Conclusion:1.The airway wall area percentage obtained by High resolution CT three-position reconstructionairway parameters can be used as an image student marker for small airway structure changes;2.Carbon black exposure caused airway wall thickening,tracheal lumen stenosis,and decreased lung function,and the exposure concentration was positively correlated with the change in WA%.Meanwhile the decrease in lung function caused by exposure was mediated by airway wall thickening.WA%can specifically evaluate the functional and structural changes in lung caused by carbon black,so this parameter can be used as a biomarker for lung imaging.