title: Impact of emphysema heterogeneity on pulmonary function.
abstract: OBJECTIVE
  To investigate the association between emphysema heterogeneity in spatial distribution, pulmonary function and disease severity.
  
  
  METHODS
  We ascertained a dataset of anonymized Computed Tomography (CT) examinations acquired on 565 participants in a COPD study. Subjects with chronic bronchitis (CB) and/or bronchodilator response were excluded resulting in 190 cases without COPD and 160 cases with COPD. Low attenuations areas (LAAs) (≤ 950 Hounsfield Unit (HU)) were identified and quantified at the level of individual lobes. Emphysema heterogeneity was defined in a manner that ranged in value from -100% to 100%. The association between emphysema heterogeneity and pulmonary function measures (e.g., FEV1% predicted, RV/TLC, and DLco% predicted) adjusted for age, sex, and smoking history (pack-years) was assessed using multiple linear regression analysis.
  
  
  RESULTS
  The majority (128/160) of the subjects with COPD had a heterogeneity greater than zero. After adjusting for age, gender, smoking history, and extent of emphysema, heterogeneity in depicted disease in upper lobe dominant cases was positively associated with pulmonary function measures, such as FEV1 Predicted (p<.001) and FEV1/FVC (p<.001), as well as disease severity (p<0.05). We found a negative association between HI% , RV/TLC (p<0.001), and DLco% (albeit not a statistically significant one, p = 0.06) in this group of patients.
  
  
  CONCLUSIONS
  Subjects with more homogeneous distribution of emphysema and/or lower lung dominant emphysema tend to have worse pulmonary function.
authors.affiliation: Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
authors.forename: Jieyang
authors.initials: J
authors.lastname: Ju
authors.affiliation: Department of Biostatistics, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
authors.forename: Ruosha
authors.initials: R
authors.lastname: Li
authors.affiliation: Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
authors.forename: Suicheng
authors.initials: S
authors.lastname: Gu
authors.affiliation: Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
authors.forename: Joseph K
authors.initials: JK
authors.lastname: Leader
authors.affiliation: Peking University Third Affiliated Hospital, Beijing, People's Republic of China.
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Wang
authors.affiliation: Peking University Third Affiliated Hospital, Beijing, People's Republic of China.
authors.forename: Yahong
authors.initials: Y
authors.lastname: Chen
authors.affiliation: School of Electrical and Computer Engineering, University of Oklahoma, Norman, Oklahoma, United States of America.
authors.forename: Bin
authors.initials: B
authors.lastname: Zheng
authors.affiliation: Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
authors.forename: Shandong
authors.initials: S
authors.lastname: Wu
authors.affiliation: Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
authors.forename: David
authors.initials: D
authors.lastname: Gur
authors.affiliation: Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
authors.forename: Frank
authors.initials: F
authors.lastname: Sciurba
authors.affiliation: Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America; Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
authors.forename: Jiantao
authors.initials: J
authors.lastname: Pu
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000503:physiopathology*; D011656:Pulmonary Emphysema / Q000145:classification / Q000150:complications / Q000503:physiopathology*; D012129:Respiratory Function Tests; D012720:Severity of Illness Index; D012907:Smoking; D014057:Tomography, X-Ray Computed