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. 2010 Apr;17(4):489-95.
doi: 10.1016/j.acra.2009.11.004. Epub 2010 Jan 12.

Collapsibility of lung volume by paired inspiratory and expiratory CT scans: correlations with lung function and mean lung density

Tsuneo Yamashiro  1 , Shin Matsuoka, Brian J Bartholmai, Raúl San José Estépar, James C Ross, Alejandro Diaz, Sadayuki Murayama, Edwin K Silverman, Hiroto Hatabu, George R Washko
Affiliations

Collapsibility of lung volume by paired inspiratory and expiratory CT scans: correlations with lung function and mean lung density

Tsuneo Yamashiro et al. Acad Radiol. 2010 Apr.

Abstract

Rationale and objectives: To evaluate the relationship between measurements of lung volume (LV) on inspiratory/expiratory computed tomography (CT) scans, pulmonary function tests (PFT), and CT measurements of emphysema in individuals with chronic obstructive pulmonary disease.

Materials and methods: Forty-six smokers (20 females and 26 males; age range 46-81 years), enrolled in the Lung Tissue Research Consortium, underwent PFT and chest CT at full inspiration and expiration. Inspiratory and expiratory LV values were automatically measured by open-source software, and the expiratory/inspiratory (E/I) ratio of LV was calculated. Mean lung density (MLD) and low attenuation area percent (<-950 HU) were also measured. Correlations of LV measurements with lung function and other CT indices were evaluated by the Spearman rank correlation test.

Results: LV E/I ratio 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)%P, R = -0.56, P < .0001; FEV(1)/FVC, r = -0.59, P < .0001; RV/TLC, r = 0.57, P < .0001, respectively). A higher correlation coefficient was observed between expiratory LV and expiratory MLD (r = -0.73, P < .0001) than between inspiratory LV and inspiratory MLD (r = -0.46, P < .01). LV E/I ratio showed a very strong correlation to MLD E/I ratio (r = 0.95, P < .0001).

Conclusions: LV E/I ratio can be considered to be equivalent to MLD E/I ratio and to reflect airflow limitation and air-trapping. Higher collapsibility of lung volume, observed by inspiratory/expiratory CT, indicates less severe conditions in chronic obstructive pulmonary disease.

Keywords: airflow obstruction; chronic obstructive pulmonary disease; computed tomography; lung volume; pulmonary emphysema.

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Conflict of interest statement

Conflicts of interest: Dr. Yamashiro, Dr. Matsuoka, Dr. Bartholmai, Dr. San Jose Estepar, Mr. Ross, Dr. Diaz, Dr. Murayama, Dr. Hatabu, and Dr. Washko have no conflicts of interest to disclose. Dr. Silverman received an honorarium for a talk on COPD genetics in 2006, and grant support and consulting fees from GlaxoSmithKline for two studies of COPD genetics. Dr. Silverman also received honoraria from Bayer in 2005, and from AstraZeneca in 2007 and 2008.

Figures

Figure 1
Figure 1. 69-year-old man with chronic obstructive pulmonary disease (GOLD stage 2)
Reconstructed coronal CT images, which are made by the software, at full inspiration (A) and full expiration (B) are shown. Lung volume (LV) expiratory/inspiratory (E/I) ratio is 0.70, and mean lung density (MLD) E/I ratio is 0.95. Note that LV is calculated based on all axial images, not on the coronal images.
Figure 2
Figure 2. Correlations between lung volume (LV) expiratory/inspiratory (E/I) ratio and lung function
Correlations between LV E/I ratio and PFT values are demonstrated. LV E/I ratio shows moderate correlations with FEV1%P, FEV1/FVC, and RV/TLC (A, B, C). A weak correlation is observed with DLco%P (D).
Figure 2
Figure 2. Correlations between lung volume (LV) expiratory/inspiratory (E/I) ratio and lung function
Correlations between LV E/I ratio and PFT values are demonstrated. LV E/I ratio shows moderate correlations with FEV1%P, FEV1/FVC, and RV/TLC (A, B, C). A weak correlation is observed with DLco%P (D).
Figure 2
Figure 2. Correlations between lung volume (LV) expiratory/inspiratory (E/I) ratio and lung function
Correlations between LV E/I ratio and PFT values are demonstrated. LV E/I ratio shows moderate correlations with FEV1%P, FEV1/FVC, and RV/TLC (A, B, C). A weak correlation is observed with DLco%P (D).
Figure 2
Figure 2. Correlations between lung volume (LV) expiratory/inspiratory (E/I) ratio and lung function
Correlations between LV E/I ratio and PFT values are demonstrated. LV E/I ratio shows moderate correlations with FEV1%P, FEV1/FVC, and RV/TLC (A, B, C). A weak correlation is observed with DLco%P (D).
Figure 3
Figure 3. Correlation between lung volume (LV) expiratory/inspiratory (E/I) ratio and mean lung density (MLD) E/I ratio
LV E/I ratio demonstrates a strong correlation with MLD E/I ratio (R=0.952, p<0.0001).
See this image and copyright information in PMC

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