title: Kurtosis and skewness of density histograms on inspiratory and expiratory CT scans in smokers.
abstract: The aim of this study is to evaluate the relationship between lung function and kurtosis or skewness of lung density histograms on computed tomography (CT) in smokers. Forty-six smokers (age range 46?81 years), enrolled in the Lung Tissue Research Consortium, underwent pulmonary function tests (PFT) and chest CT at full inspiration and full expiration. On both inspiratory and expiratory scans, kurtosis and skewness of the density histograms were automatically measured by open-source software. Correlations between CT measurements and lung function were evaluated by the linear regression analysis. Although no significant correlations were found between inspiratory kurtosis or skewness and PFT results, expiratory kurtosis significantly correlated with the following: the percentage of predicted value of forced expiratory volume in the first second (FEV(1)), the ratio of FEV(1) to forced vital capacity (FVC), and the ratio of residual volume (RV) to total lung capacity (TLC) (FEV(1)%predicted, R = -0.581, p < 0.001; FEV(1)/FVC, R = -0.612, p < 0.001; RV/TLC, R = 0.613, p < 0.001, respectively). Similarly, expiratory skewness showed significant correlations with PFT results (FEV(1)%predicted, R = -0.584, p < 0.001; FEV(1)/FVC, R = -0.619, p < 0.001; RV/TLC, R = 0.585, p < 0.001, respectively). Also, the expiratory/inspiratory (E/I) ratios of kurtosis and skewness significantly correlated with FEV(1)%predicted (p < 0.001), FEV(1)/FVC (p < 0.001), RV/TLC (p < 0.001), and the percentage of predicted value of diffusing capacity for carbon monoxide (kurtosis E/I ratio, p = 0.001; skewness E/I ratio, p = 0.03, respectively). We conclude therefore that expiratory values and the E/I ratios of kurtosis and skewness of CT densitometry reflect airflow limitation and air-trapping. Higher kurtosis or skewness on expiratory CT scan indicates more severe conditions in smokers.
authors.affiliation: Center for Pulmonary Functional Imaging, Brigham and Women's Hospital, Boston, MA, USA. clatsune@yahoo.co.jp
authors.forename: Tsuneo
authors.initials: T
authors.lastname: Yamashiro
authors.forename: Shin
authors.initials: S
authors.lastname: Matsuoka
authors.forename: Raúl San José
authors.initials: RS
authors.lastname: Estépar
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Bartholmai
authors.forename: Alejandro
authors.initials: A
authors.lastname: Diaz
authors.forename: James C
authors.initials: JC
authors.lastname: Ross
authors.forename: Sadayuki
authors.initials: S
authors.lastname: Murayama
authors.forename: Edwin K
authors.initials: EK
authors.lastname: Silverman
authors.forename: Hiroto
authors.initials: H
authors.lastname: Hatabu
authors.forename: George R
authors.initials: GR
authors.lastname: Washko
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003627:Data Interpretation, Statistical; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D008171:Lung Diseases / Q000000981:diagnostic imaging / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D016011:Normal Distribution; D011653:Pulmonary Diffusing Capacity; D029424:Pulmonary Disease, Chronic Obstructive / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D012115:Residual Volume; D012907:Smoking / Q000503:physiopathology*; D014057:Tomography, X-Ray Computed; D014109:Total Lung Capacity; D014797:Vital Capacity