Current Smoking Status Is Associated With Lower Quantitative CT Measures of Emphysema and Gas Trapping

Content Provider	Scilit
Author	Williams, Andre Jou, Sung-Shiick Yagihashi, Kunihiro Everett, Douglas Hokanson, John E. Stinson, Douglas Lynch, David A.
Copyright Year	2016
Description	Journal: Journal of Thoracic Imaging The purposes of this study were to evaluate the effect of smoking status on quantitative computed tomography CT measures of low-attenuation areas (LAAs) on inspiratory and expiratory CT and to provide a method of adjusting for this effect. A total of 6762 current and former smokers underwent spirometry and volumetric inspiratory and expiratory CT. Quantitative CT analysis was completed using open-source 3D Slicer software. LAAs were defined as lung voxels with attenuation values ≤-950 Hounsfield units (HU) on inspiratory CT and ≤-856 HU on expiratory CT and were expressed as percentage of CT lung volume (%LAAI-950 and %LAAE-856). Multiple linear regression was used to determine the effect of smoking status on %LAAI-950 and %LAAE-856 while controlling for demographic variables, spirometric lung function, and smoking history, as well as total lung capacity (%LAAI-950) or functional residual capacity (%LAAE-856). Quantile normalization was used to align the %LAAI-950 distributions for current and former smokers. Mean %LAAI-950 was 4.2±7.1 in current smokers and 7.7±9.7 in former smokers (P<0.001). After adjusting for confounders, %LAAI-950 was 3.5 percentage points lower and %LAAE-856 was 6.0 percentage points lower in current smokers than in former smokers (P<0.001). After quantile normalization, smoking status was an insignificant variable in the inspiratory regression model, with %LAAI-950 being 0.27 percentage points higher in current smokers (P=0.13). After adjusting for patient demographics and lung function, current smokers display significantly lower %LAAI-950 and %LAAE-856 than do former smokers. Potential methods for adjusting for this effect would include adding a fixed value (eg, 3.5%) to the calculated percentage of emphysema in current smokers, or quantile normalization.
Related Links	http://europepmc.org/articles/pmc4677600?pdf=render https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4677600/pdf
Ending Page	36
Page Count	8
Starting Page	29
ISSN	08835993
e-ISSN	15360237
DOI	10.1097/rti.0000000000000181
Journal	Journal of Thoracic Imaging
Issue Number	1
Volume Number	31
Language	English
Publisher	Ovid Technologies (Wolters Kluwer Health)
Publisher Date	2016-01-01
Access Restriction	Open
Subject Keyword	Journal: Journal of Thoracic Imaging Respiratory System Quantitative Computed Tomography Air Trapping Chronic Obstructive Pulmonary Disease
Content Type	Text
Resource Type	Article
Subject	Pulmonary and Respiratory Medicine Radiology, Nuclear Medicine and Imaging