Study And Application On Optimization Programs In The Dignosis Of Small Airway Disease In Children

Objective: Volume dates of children,s chest CT were used to study the differences of two different reconstruction algorithms and four reconstruction slice thickness in displaying the small airways. Structure of small airways were displayed in different radiation doses. And the optimization program,to display the small airways of lungs,was researched.Methods:①Optimal thickness and optimal reconstruction algorithm: Volume datas of 200 patients with chest spiral CT (MSCT) were retrospectively analysised.VHRCT and standard algorithms were used to display the small airways in 0.625mm, 1.25mm, 2.5 mm and 5mm, respectively.And image quality of two algorithms and different thickness on the small bronchi of the left lung tip section were compared.②Dose selection: volume and conventional HRCT scan in lung phantom MSCT: tube voltage 120kV, tube current 120mA, 100 mA, 80 mA, 50mA, 20mA,respectively.Dose of two different scanning methods and different tube current and the image quality were compared between HRCT and VHRCT.Results:①Two reconstruction algorithms and four different thickness were used to observe the small structure of small airway. In the same thickness, VHRCT shows a better image than the standard reconstruction to discover the bronchiole of left apical segment.In VHRCT , both 0.625mm and 1.25mm thickness can show the bronchiole of left apical segment clearly , there was no significant difference (P> 0.05),but the scores of 0.625mm was higher than 1.25mm, suggest that the best image display was 0.625mm.②In different tube currents, difference were studied between VHRCT and HRCT in 0.625mm:In the same tube currents,both MSCT and HRCT scan,there was a positive proportional relationship between CTDIw or DLP and the tube current. 120kV in the tube voltage, 120mA, 100 mA, 80 mA, 50mA in tube current , VHRCT and HRCT images can clearly show the situation of small airway, there was no significant difference (P> 0.05), both VHRCT and HRCT can not clearly display the small airway in 20mA of tube current.Conclusion:①VHRCT is better than standard reconstruction to discover the small airway of lungs.②0.625mm is the best to discover the bronchiole in different thickness of VHRCT.③In the same tube current, there is a positive proportional relationship between radiation dose and MSCT or HRCT.④There is no significant difference to discover the small structure between VHRCT and HRCT, demostrate that VHRCT can replace HRCT to dignosis the disease of small airway ,without increasing the radiation dose .⑤In VHRCT, 120kV in tube voltage, more than 50mA in tube current and thickness in 0.625mm,small structure of lungs can be showed clearly.This program can be used as optimization strategy to display disease of small airway.Objective:To explore the thin reconstruction of low-dose 64-slice CT in 117 children with mycoplasma pneumoniae pneumonia,to study small airway feature in the VHRCT of mycoplasma pneumonia.Methods:117 children with mycoplasma pneumonia underwent low-dose64-slice chest CT scan, tube voltage: 120kV, tube current: 50mA, and volume HRCT reconstruction.Results:The results of the thin reconstruction of low-dose 64-slice CT in 117 cases were as follows: Consolidation were observed in 93 cases, lobar or segmental consolidation were observed in 76 cases, which with bronchial inflatable sign in 34 cases and with mild volume decrease of the involved lobe in 18 cases; lobular consolidation were observed in 17 cases.Lymphadenectasis were showed in 37 cases and pleural effusion were seen in 36 cases; pneumothorax and mediastinal emphysema were detected in 3 cases and 2 cases. Small airway changes: tree in bud was observed in 59 cases, centrilobular nodules in 54 cases, ground-glass shadow in 15 cases, mosaic perfusion syndrome in 11 cases and small bronchiectasis in 26 cases.Conclusion:The main appearances of children with mycoplasma pneumoniae pneumonia are the tree-in-bud pattern or centrilobular nodules,which can appearence with consolidation The tree-in-bud pattern are vague of edges and low density. Thin reconstruction volume HRCT have a novel value in diagnosis of mycoplasma pneumoniae pneumonia in children.