Potential Capability Of Multi-slice CT Scanning In Predicting Acute Exacerbation And Hospitalizations In Patients With COPD

Background: Acute exacerbation is a symbol event in the disease duration of COPD and patient with frequent AE tend to have more AE and poor prognosis.COPD poses great challenges to the health care system due to its high prevalence,morbidity and mortality.Therefore,to predict and avoid AE has been endeavored for years.However,no satisfying single item or method has been found to date.The main causes of airway lesions in COPD patients are small airway narrowing caused by fibrosis and surrounding airway collapse caused by loss of parenchymal elasticity.Emphysema is pathologically defined as a permanent widening of the air gap at the distal end of the terminal bronchiole with wall destruction and no apparent fibrosis.Multi-slice CT has been used to measure airway index and emphysema in COPD patients.Quantitative CT uses software threshold segmentation technology and three-dimensional post-processing technology for more automatic quantitative analysis of the target,its accuracy,repeatability is strong,in the study of COPD can more accurately reflect the changes of lung pathology and anatomy.CT quantitative study of airway remodeling and lung parenchyma changes can make our study of chronic obstructive pulmonary disease more in-depth.Objective: To investigate the capability of quantitative CT in predicting acute exacerbation and hospitalizations in patients with COPD.Methods: This study was approved by the Ethics Committee of the hospital.According to clinical manifestations（chronic respiratory symptoms such as recurrent cough,expectoration and dyspnea）and previous lung function examinations（after inhaling bronchodilators,First second forced respiratory volume（FEV1）/forced vital capacity（FVC）< 0.70）of patients diagnosed with COPD were retrospectively analyzed.Lung CT images of patients eligible for inclusion were collected during visited the hospitalization,and quantitative CT analysis of the included data was conducted by using the GE Thoracic VCAR.Percentage of wall area（%WA）,ratio of airway wall thickness to total diameter（WT/D）and low attenuation area volume percentage（the percentage of lung volumes with CT attenuation value below-950 HU[%LAA]）were received.Among them,we selected four bronchus of left upper apical bronchus,right upper apical bronchus,left lower posterior base bronchus and right lower posterior base bronchus to measure the targeted bronchus,and calculated the emphysema index of left lung,right lung and whole lung respectively.Date of frequency of hospitalizations due to acute exacerbation in the prior year was retrieved using a questionnaire.Patients were grouped according to how often they had been hospitalized in the past year,Factors leading to acute exacerbation and hospitalizations were analyzed.Results: The frequency of hospitalizations due to acute exacerbation in the previous year was higher in the aged COPD patients.Significantly CT metric changes were found in hospitalized patients compared with patients with acute exacerbation but not hospitalized（P<0.001）.Airway change indicators %WA and WT/D of the four chosen subsegmental bronchi and emphysema parameter %LAA were higher in the frequent hospitalization patients.Using logistic regression,%LAA≥10% and s PAP>50mmhg were independently associated with frequent re-hospitalizations.Conclusions: Quantitative multi-slice CT examination could be potentially help for predicting acute exacerbation and hospitalizations in COPD patients.Emphysema and pulmonary artery pressure could be predictors for re-hospitalizations.