title: Relationships between diffusing capacity for carbon monoxide (DLCO), and quantitative computed tomography measurements and visual assessment for chronic obstructive pulmonary disease.
abstract: OBJECTIVE
  To evaluate the relationships between DLCO, and Quantitative CT (QCT) measurements and visual assessment of pulmonary emphysema and to test the relative roles of visual and quantitative assessment of emphysema.
  
  
  METHODS
  The subjects included 199 current and former cigarette smokers from the COPDGene cohort who underwent inspiratory and expiratory CT and also had diffusing capacity for carbon monoxide corrected for alveolar volume (DLCO/VA). Quantitative CT measurements included % low attenuation areas (%LAA-950ins=voxels ≤-950 Hounsfield unit (HU), %LAA-910ins, and %LAA-856ins), mean CT attenuation and 15th percentile HU value on inspiratory CT, and %LAA-856exp (voxels ≤-856 HU on expiratory CT). The extent of emphysema was visually assessed using a 5-point grading system. Univariate and multiple variable linear regression analyses were employed to evaluate the correlations between DLCO/VA and QCT parameters and visual extent of emphysema.
  
  
  RESULTS
  The DLCO/VA correlated most strongly with 15th percentile HU (R(2)=0.440, p<0.001) closely followed by %LAA-950ins (R(2)=0.417, p<0.001) and visual extent of emphysema (R(2)=0.411, p<0.001). Multiple variable analysis showed that visual extent of emphysema and 15th percentile HU were independent significant predictors of DLCO/VA at an R(2) of 0.599.
  
  
  CONCLUSIONS
  15th percentile HU seems the best parameter to represent the respiratory condition of COPD. Visual and Quantitative CT assessment of emphysema provide complementary information to QCT analysis.
authors.affiliation: Department of Radiology, National Jewish Health, 1400 Jackson Street, Denver, CO 80206, USA; Department of Radiology, Teikyo University Mizonokuchi Hospital, Japan. Electronic address: nambu-a@gray.plala.or.jp.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Nambu
authors.affiliation: Department of Radiology, National Jewish Health, 1400 Jackson Street, Denver, CO 80206, USA. Electronic address: ZachJ@NJHealth.org.
authors.forename: Jordan
authors.initials: J
authors.lastname: Zach
authors.affiliation: Department of Radiology, National Jewish Health, 1400 Jackson Street, Denver, CO 80206, USA. Electronic address: Joyce.schroeder@stanfordalumni.org.
authors.forename: Joyce
authors.initials: J
authors.lastname: Schroeder
authors.affiliation: Department of Radiology, National Jewish Health, 1400 Jackson Street, Denver, CO 80206, USA; Department of Radiology, Chonbuk National University Hospital, Republic of Korea. Electronic address: gyjin@chonbuk.ac.kr.
authors.forename: Gong Yong
authors.initials: GY
authors.lastname: Jin
authors.affiliation: Department of Radiology, National Jewish Health, 1400 Jackson Street, Denver, CO 80206, USA; Department of Radiology, Chungnam National Hospital, Chungnam National University School of Medicine, Republic of Korea. Electronic address: haneul88@hanmail.net.
authors.forename: Song Soo
authors.initials: SS
authors.lastname: Kim
authors.affiliation: Department of Medicine, National Jewish Health, Denver, CO, USA; Department of Internal Medicine, Chonnam National University Hospital, Gwangju, Republic of Korea. Electronic address: kyionly@chonnam.ac.kr.
authors.forename: Yu-Il
authors.initials: YI
authors.lastname: Kim
authors.affiliation: Department of Medicine, National Jewish Health, Denver, CO, USA. Electronic address: SchnellC@NJHealth.org.
authors.forename: Christina
authors.initials: C
authors.lastname: Schnell
authors.affiliation: Division of Pulmonary Medicine, Department of Medicine, National Jewish Health, USA. Electronic address: BowlerR@NJHealth.org.
authors.forename: Russell
authors.initials: R
authors.lastname: Bowler
authors.affiliation: Department of Radiology, National Jewish Health, 1400 Jackson Street, Denver, CO 80206, USA. Electronic address: LynchD@NJHealth.org.
authors.forename: David A
authors.initials: DA
authors.lastname: Lynch
mesh_terms: D000368:Aged; D002248:Carbon Monoxide; D045853:Exhalation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011653:Pulmonary Diffusing Capacity; D029424:Pulmonary Disease, Chronic Obstructive / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology; D011857:Radiographic Image Interpretation, Computer-Assisted; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012907:Smoking / Q000009:adverse effects*; D014057:Tomography, X-Ray Computed / Q000379:methods
chemical_list: D002248:Carbon Monoxide
keywords: CT; Chronic obstructive pulmonary disease; Diffusion capacity for carbon monooxide; Emphysema; Lung