Measurement Of Airway Diameter Of Normal Adult By Low-dose Multi-slice Spiral CT And Analysis Of Its Relevant Factors

Objective:By using low-dosed multi-slice spiral computed tomography to measure Chinese normal adult trachea diameter in inspiratory and expiratory phase with window width 1500 Hu and window level-450 Hu,to analyse correlation of different influencing factors with airway diameter,such as inspiratory phase and expiratory phase,gender,age,height,weight and body mass index.To assist the clinical to select suitable size of airway stent and tracheal intubation.Materials and Methods:243 subjects for routine chest low-dose multi-slice CT scan in our hospital were collected.Their clinical information and CT images of deep inspiratory phase and deep expiratory phase scanning were also collected.And then reconstructing CT images to ultrathin CT and measured trachea and bronchus diameter of different parts by the window width 1500 Hu and window level-450 Hu.In the tracheal diameter section,transverse-midclavicular tracheal diameter,anteroposteriormidclavicular tracheal diameter,transverse-aortic arch tangent tracheal diameter and anteroposterior-aortic arch tangent tracheal diameter were measured in the axial CT scans.And combined with the auxiliary line,transverse-aortic arch tangent tracheal diameter were measured in the coronal CT scans.Left and right main bronchus internal diameters were measured at the place of subcarinal 1 cm.Statistical method: This study used SPSS 20.0 software for statistical analysis.By t text and Pearson,we analysed correlation of different gender,age,height,weight,body mass index,and respiratory phases of airway diameters of different parts,left and right main bronchus lengths.All statistical tests were two-sided.There was a statistically significant difference when P<0.05,and an obvious statistically significant difference when P<0.01.The statistical results of the measurement data are expressed as mean±standard deviation(?X±S).Result: The 243 subjects were 127 men and 116 women,their age were 20~79 years old,average(48.06±16.23)years old.All the parameters measured of the trachea and bronchus,including diameter of different parts of the trachea,diameter and length of the left and right main bronchus,were statistically significant for different gender and different respiratory phases(P<0.01).And difference of the trachea diameters in inspiratory phase and breath difference was different.The difference of anteroposterior-midclavicular tracheal diameter,anteroposterior-aortic arch tangent tracheal diameter was more obvious than other parts.There was a linear correlation between trachea diameter of the inspiratory phase and the inspiratory phase.The linear relationship in males at midclavicular tracheal diameter between inspiratory phase(x)and expiratory phase(y)can be expressed as: y = 0.66x+4.6516(r = 0.7215);The linear relationship in males at aortic arch tangent tracheal diameter between inspiratory phase(x)and expiratory phase(y)can be expressed as: y = 0.808 x +1.9486(r = 0.8323);The linear relationship in females at midclavicular tracheal diameter between inspiratory phase(x)and expiratory phase(y)can be expressed as: y = 0.626x+4.2029(r = 0.7315);The linear relationship in females at aortic arch tangent tracheal diameter between inspiratory phase(x)and expiratory phase(y)can be expressed as: y = 0.8373 x +1.0412(r = 0.8093).There was statistically difference between transverse-midclavicular tracheal diameter and anteroposterior-midclavicular tracheal diameter in the axial CT scans(15.43±2.22 vs 15.95±2.13,P<0.01).That was,different parts of the trachea had different width.There was no statistical correlation of tracheal diameter between different gender,age,height,weight,body mass index.Coefficient of variation of the right main bronchus length was most obvious of all the measured parameters(males 23.17%,females 25.07%).That was,the right main bronchus length has larger discrete degree individually.Conclusion: It is feasible to measure the diameter of the trachea and the main bronchial diameter by the low-dose multi-slice spiral CT at the window width 1500 Hu and the window level-450 Hu.Trachea diameters were different between inspiratory phase and expiratory phase of different individuals.And there was a good linear correlation between them.Lengths of the main bronchus were also different among different individuals.The choice of diameter of tracheal stent,length of right main bronchial stent and diameter tracheal intubation should be individualized.