The Study Of Chronic Obstructive Pulmonary Disease With Dynamic Low-dose Multislice CT

Chronic obstructive pulmonary disease (COPD) is a disease state characterized by airflow limitation that is not fully reversible. The airflow limitation is usually both progressive and associated with an abnormal inflammatory response of the lungs to noxious particle or gases. This include emphysema and chronic bronchitis. COPD is a major public health problem. It is the fourth leading cause of chronic morbidity and mortality in the world and is projected to rank fifth in 2020 as a worldwide burden of disease according to a study published by the World Bank/World Health Organization. Presently, most of the studies in radiology of COPD focus on measurement of pixel index and comparing it with pulmonary function test. Moreover, findings of asymptomatic smokers and early stage of COPD on CT are becoming the hotspot. According to the airway changes of COPD, only small airway has been regarded. However, pathologic changes of central airway are the causes of chronic cough and sputum production, and it persisted in the entire courses of COPD. So, more attentions were paid to the diagnosis, treatment and follow-up of central airway in COPD. Now, some documents have reported about quantitative measurement of airway dimensions and areas by CT, but there wasn' t about imaging changes in different stages of COPD and dynamic quantitative study of bronchus. This study included three parts:Part Ⅰ : Study of Parameter of Low-dose MultisliceCT Volumetric scan in COPDPurpose: To study the optimal parameter of low-dose multislice CT scan in COPD.Material and Methods: A photom was scanned using tube current 280mA and 50mA by MSCT(GE, LightSpeedl6), the absorbing doses were measured. 20 patients were performed CT scan using tube current 200mA, 100mA, 50mA and 25mA at the level of upper lobes. The following parameters were used: 120kV, pitch 1. 375:1, rotation time 0. 5s, layer thickness 1. 25mm. The imaging quality was evaluated by two radiologists , and the mean lung density and lung capacity were measured. For 15 patients, total lungs were examined by MSCT using 280mA and 50mA. The voxel index(VI) were compared.Results: When tube current was 280mA, the absorbing doses of central and peripheral model were 7. 52 mGy and 15. 23 mGy, respectively. When tube current was 50mA, the absorbing doses of central and peripheral model were 1. 34 mGy and 2. 72 mGy, respectively. The imaging quality was lower with dose decreasing, but the scores were higher than 3 when tube current was not less than 50mA. The average mean lung densities obtained at 4 tube current CT scans were - 849.300 ± 1.202HU(200mA), -851. 350±l. 201HU(100mA), -848. 550±1. 203HU(50mA), -847. 550±l. 202HU(25mA), F=l. 795, P=0.158. The average lung capacities obtained 4 tube current CT scans were 206. 015 + 0. 903ml, 206. 963 ± 0.903ml, 205.211 ± 0.905ml, 209.439 ± 0.904ml, respectively, F=4. 125, P=0. 010. Further compare were taken, it was confirmed that the average lung capacity obtained by 25mA CT scan was lower than those obtained by 200mA and 50mA CT scans (P=0. 046, P=0. 009, respectively). The dose length products (DLP) obtained by 280mA and 50mA CT scans were 282. 2085 + 38. 0879mGyXcm and 50. 9945± 6. 9339mGyXcm, respectively,t=26. 709, P<0. 001. The Vis obtained by 280mA and 50mA CT scans were 21.0580+16. 6659%ifP 25.2590+15.3342%, respectively, t=-0.830, p=0. 700.Conclusion: With the decreasing of tube current, the absorbing dose was decreased linearly. 50mA is the optimal tube current for evaluation of bronchus and measurements of lung.PartII: MSCT in Evaluation Airway of COPD: Feasibility and Compare between Imaging and Pathologic ResultsPurpose: To discuss the pathologic basis of airway remodeling appearance using MSCT. To discuss the correlation between airway measurement at the trunk of apical bronchus of the right upper lobe and the mean value measured at small airways.Material and Methods: 15 patients who were performed lung resection because of peripheral solitary nodules were recruited, including 5 non-COPD patients, 3 stageO COPD patients , 5 stagel patients , and 2 stage2 patients. Total lung were scanned. The parameter included 120kVp, 50mA, pitch 1.375:1, rotation time 0.5s. With the patient' s informed consent, the cine scan was taken at the level of the apical bronchus of right upper lobe section(Bi) or the inferior pulmonary vein section. The parameters included 120kV, 35mA, thickness 10mm, during time 9. Is, which included 2-3 respiratorv cycles. The samples were stained by HE and Masson method. 15 COPD patients (4 stagel, 5 stage2, 4 stage3, and 2 stage4) were examined by CT. The TDR and WA% of the apical bronchus of right upper lobe section were evaluated. The mean TDR and WA% of small airway were measured at the apical bronchus of right upper lobe section, the carina section, and the inferior pulmonary vein section.Results: With the progressing, the airway wall became thicken andelastic force decreased. In pathology, there were mucus hyperplasia and rupture of smooth muscle, respectively. For the apical bronchus of right upper lobe, the TDR was 0. 2990 + 3. 880E-02, the WA% was 76. 60 + 9.612%. For the small airways, the average TDR was 0. 2633 + 5. 314E-02, and the average WA% was 83. 00 ±5. 237%. The r value were 0.793 and 0. 784 , respectively. After t test, the TDR and WA% of B, were lower than those of small airway(t=2.099 for TDR, t=2.264 for WA%, P<0.05, respectively).Conclusion: In early COPD, the basis of CT findings were mucus hyperplasia and rupture of smooth muscle at bronchus and bronchiole. There were good correlations for TDR and WA% between the apical bronchus of right upper lobe and small airway.Partlll: Study of Airway and Density in COPD using Low-dose Dynamic Multislice CTPurpose: To study airway dimensions and lung density changes in different stages of COPD, and to study dynamic airway change during respiration.Material and Methods: 67 patients of COPD were selected, including 12 stageO patients, 16 stagel petients,16 stage2 patients, 14 stage3 patients, 9 stage4 patients. The control group included 15 non-COPD patients. The total lung was scanned by low-dose MSCT during inspiration. The upper lobes , which contained the apical bronchus of right upper lobe, were examined by low-dose MSCT during expiration. MSCT cine scan were taken at the level of the apical bronchus of right upper lobe. The MLD and VI of inspiration were measured. A.,, TDR and WA% of the apical bronchus of right upper lobe were measured at end-inspiration and end-expiration. The dynamic changes of central and peripheral airways were evaluated by tow radiologists using cine...