CT Quantitative Assessment Of Small Airway Disease In COPD Patients And Its Correlation With Pulmonary Function Test

Objective: 1.To quantitatively analyze the airway structural indexes and the emphysema index(EI)of patients with chronic obstructive pulmonary disease(COPD);2.To explore the correlations between structural indexes in different grades of small airway,emphysema index and pulmonary function in COPD patients;3.To explore the relationship between small airway structural parameters,emphysema index and the severity of COPD;4.To clarify the quantitative analysis ability of high resolution CT in combination with ISP 9.0 system for small airway reconstruction of COPD.Methods: In this research,we selected 24 COPD patients and 14 healthy medical examiners(control group)as the research objects from the Respiratory Department and the physical examination center,respectively,of Qingdao Municipal Hospital of Qingdao University.The COPD patinets had been followed up since November 2017 till November 2018.All subjects had taken the high resolution CT(HRCT)and pulmonary function test(PFT)in the same period.According to GOLD 2018,the COPD patients were divided into 4 groups,which were GOLD stage I group with 7 cases,GOLD stage II group with 8 cases,GOLD stage III group wiht 6 cases,and GOLD stageIV group with 3 cases.Among the 4 groups,GOLDI and GOLDII was defined as the early stage of COPD,and GOLDIII and GOLD IVgroups was defined as the late stage of COPD.And the healthy medical examiners were divided into the normal pulmonary function group(8 cases)and the small airway disease group(6 cases).We reconstructed the CT images of COPD patients' lungs with ISP 9.0 software to automatically obtain the emphysema index(EI),i.e.the percentage of lung voxels less than-950 HU,of each lung lobe.Simultaneously,we semi-automatically calculated the parameters of small airway in the third,fifth,and ninth grades of the following 8 bronchial pathways: LB1+2(apicoposterior segment of the left upper lobe),LB4(superior lingular segment of the left upper lobe),LB6(superior segment of the left lower lobe),LB9(lateral basal segment of the left lower lobe),RB1(apical segment of the right upper lobe),RB4(lateral segment of the right middle lobe),RB6(superior segment of the right lower lobe),and RB9(lateral basal segment of the right lower lobe).The parameters took into consideration were Wall Area(WA),Lumen Area(LA)and total Airway Area(AA).The aforementioned data were analyzed to find the differences among the parameters(EI,WA,LA,AA,W / A,and L / A)of each group,and the correlation between CT reconstruction indicators and pulmonary function,the severity of COPD.Results: 1.The correlations were found between the pulmonary function and the small airway parameters of the third,the fifth,the ninth generations of bronchi,respectively.The correlations in the ninth generations of bronchi was better than that in the third and the fifth generations.(FEV1% L/A: r3=0.429,r5=0.583,r9=.592,P <0.05;W/A: r3=-.428,r5=-.532,r9=-.570,P<0.05;MMEF% L/A: r3=0.421,r5=0.566,r9=.610,P<0.05;W/A: r3=-.421,r5=-.529,r9=-.593,P <0.05).2.There was no significant difference in the L A,L / A parameters of the 9th generation of bronchi in patients of GOLD II,GOLD III,and GOLD IV groups.However,in the high-risk group of COPD(SAD)and early stage of COPD,there was significant change of L A and L / A with the progression of COPD(P <0.05).3.The EI in the late COPD stage was significantly higher than those of the early COPD stage and the control group(P <0.05).There was no difference in EI between early COPD stage and the control group.Conclusion: In the early stage of COPD,significant airway remodeling has already occurred.With the progression of COPD,emphysema become the main pathological changes in the late stage of COPD.The ISP9.0 system can directly analyze the CT images of COPD,objectively evaluate the structural characteristics of each stage of COPD,and provide a scientific basis for accurate assessment of COPD.