Kurtosis and skewness of density histograms on inspiratory and expiratory CT scans in smokers

Tsuneo Yamashiro, Shin Matsuoka, Raúl San José Estépar, Brian Jack Bartholmai, Alejandro Diaz, James C. Ross, Sadayuki Murayama, Edwin K. Silverman, Hiroto Hatabu, George R. Washko

Research output: Contribution to journalArticle

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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 (FEV1), the ratio of FEV1 to forced vital capacity (FVC), and the ratio of residual volume (RV) to total lung capacity (TLC) (FEV1%predicted, R =-0.581, p < 0.001; FEV1/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 (FEV1%predicted, R =-0.584, p < 0.001; FEV1/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 FEV1%predicted (p < 0.001), FEV1/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.

Original languageEnglish (US)
Pages (from-to)13-20
Number of pages8
JournalCOPD: Journal of Chronic Obstructive Pulmonary Disease
Volume8
Issue number1
DOIs
StatePublished - Feb 2011

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Total Lung Capacity
Residual Volume
Vital Capacity
Tomography
Respiratory Function Tests
Lung
Densitometry
Forced Expiratory Volume
Carbon Monoxide
Linear Models
Thorax
Software
Air
Regression Analysis
Research

Keywords

  • Airflow limitation
  • Chronic obstructive pulmonary disease
  • Computed tomography
  • Density histogram
  • Pulmonary emphysema

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine

Cite this

Kurtosis and skewness of density histograms on inspiratory and expiratory CT scans in smokers. / Yamashiro, Tsuneo; Matsuoka, Shin; Estépar, Raúl San José; Bartholmai, Brian Jack; Diaz, Alejandro; Ross, James C.; Murayama, Sadayuki; Silverman, Edwin K.; Hatabu, Hiroto; Washko, George R.

In: COPD: Journal of Chronic Obstructive Pulmonary Disease, Vol. 8, No. 1, 02.2011, p. 13-20.

Research output: Contribution to journalArticle

Yamashiro, T, Matsuoka, S, Estépar, RSJ, Bartholmai, BJ, Diaz, A, Ross, JC, Murayama, S, Silverman, EK, Hatabu, H & Washko, GR 2011, 'Kurtosis and skewness of density histograms on inspiratory and expiratory CT scans in smokers', COPD: Journal of Chronic Obstructive Pulmonary Disease, vol. 8, no. 1, pp. 13-20. https://doi.org/10.3109/15412555.2010.541537
Yamashiro, Tsuneo ; Matsuoka, Shin ; Estépar, Raúl San José ; Bartholmai, Brian Jack ; Diaz, Alejandro ; Ross, James C. ; Murayama, Sadayuki ; Silverman, Edwin K. ; Hatabu, Hiroto ; Washko, George R. / Kurtosis and skewness of density histograms on inspiratory and expiratory CT scans in smokers. In: COPD: Journal of Chronic Obstructive Pulmonary Disease. 2011 ; Vol. 8, No. 1. pp. 13-20.
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AU - Diaz, Alejandro

AU - Ross, James C.

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N2 - 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 (FEV1), the ratio of FEV1 to forced vital capacity (FVC), and the ratio of residual volume (RV) to total lung capacity (TLC) (FEV1%predicted, R =-0.581, p < 0.001; FEV1/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 (FEV1%predicted, R =-0.584, p < 0.001; FEV1/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 FEV1%predicted (p < 0.001), FEV1/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.

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