Characterizing Functional Lung Heterogeneity in COPD Using Reference Equations for CT Scan-Measured Lobar Volumes

Come, Carolyn E.; Díaz, Alejandro A.; Curran‐Everett, Douglas; Muralidhar, N; Hersh, Craig P.; Zach, Jordan; Schroeder, Joyce; Lynch, David A.; Celli, Bartolomé R.; Washko, George R.

doi:10.1378/chest.12-1616

Cited by 12 publications

(14 citation statements)

References 33 publications

(22 reference statements)

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“…The two latter spirometric measures of lung function were expressed as percent of predicted values . Total lung capacity (TLC) was measured using CT scan …”

Section: Methodsmentioning

confidence: 99%

Bronchoarterial ratio in never‐smokers adults: Implications for bronchial dilation definition

et al. 2016

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Background and objective Bronchiectasis manifests as recurrent respiratory infections and reduced lung function. Airway dilation, which is measured as the ratio of the diameters of the bronchial lumen (B) and adjacent pulmonary artery (A), is a defining radiologic feature of bronchiectasis. A challenge to equating the BA ratio to disease severity is that the diameters of airway and vessel in health are not established. We sought to explore the variability of BA ratio in never smokers without pulmonary disease and its associations with lung function. Methods Objective measurements of the BA ratio on volumetric CT scans and pulmonary function data were collected in 106 never smokers. The BA ratio was measured in the right upper lobe apical bronchus (RB1) and the right lower lobe basal posterior bronchus. The association between the BA ratio and forced expiratory volume in one second (FEV1) was assessed using regression analysis. Results The BA ratio was 0.79 ± 0.16 and was smaller in more peripheral RB1 bronchi (P<0.0001). The BA ratio was >1, a typical threshold for bronchiectasis, in 10 (8.5%) subjects. Subjects with a BA ratio >1 (vs. ≤1) had smaller artery diameters (P<0.0001) but not significantly larger bronchial lumens. After adjusting for age, sex, race, and height, the BA ratio was directly related to FEV1 (P=0.0007). Conclusion In never smokers, the BA ratio varies by airway generation and is associated with lung function. A BA ratio >1 is driven by small arteries. Using artery diameter as reference to define bronchial dilation seems inappropriate.

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“…The two latter spirometric measures of lung function were expressed as percent of predicted values . Total lung capacity (TLC) was measured using CT scan …”

Section: Methodsmentioning

confidence: 99%

Bronchoarterial ratio in never‐smokers adults: Implications for bronchial dilation definition

et al. 2016

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“…No other similarly large cohort of nonsmokers is available for validation of the full-lung equations, although the authors of a recent publication on lobar volumes visualized on CT scans of smokers found somewhat similar differences by sex, height, and African-American race/ ethnicity, but not age and body mass index (other racial and ethnic groups were not included) (37).…”

Section: Original Researchmentioning

confidence: 99%

“…Indeed, researchers in small studies have suggested that percent emphysema varies among healthy never-smokers by demographic factors (33)(34)(35)(36); however, these studies were limited by modest sample sizes, restricted racial and ethnic distributions, and lack of population-based sampling. Investigators in a larger study recently reported that lobar lung volumes on CT scans vary by sex, height, and race (37); however, that study included mostly older smokers, who are unlikely to have structurally normal lungs, and the researchers did not address percent emphysema or total lung volumes.…”

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confidence: 99%

Variation in the Percent of Emphysema-like Lung in a Healthy, Nonsmoking Multiethnic Sample. The MESA Lung Study

Hoffman

Ahmed²,

Baumhauer³

et al. 2014

Annals ATS

104

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Rationale: Computed tomography (CT)-based lung density is used to quantitate the percentage of emphysema-like lung (hereafter referred to as percent emphysema), but information on its distribution among healthy nonsmokers is limited.Objectives: We evaluated percent emphysema and total lung volume on CT scans of healthy never-smokers in a multiethnic, population-based study. Methods:The Multi-Ethnic Study of Atherosclerosis (MESA) Lung Study investigators acquired full-lung CT scans of 3,137 participants (ages 54-93 yr) between 2010-12. The CT scans were taken at full inspiration following the Subpopulations and Intermediate Outcome Measures in COPD Study (SPIROMICS) protocol. "Healthy never-smokers" were defined as participants without a history of tobacco smoking or respiratory symptoms and disease. "Percent emphysema" was defined as the percentage of lung voxels below 2950 Hounsfield units. "Total lung volume" was defined by the volume of lung voxels.Measurements and Main Results: Among 854 healthy neversmokers, the median percent emphysema visualized on full-lung scans was 1.1% (interquartile range, 0.5-2.5%). The percent emphysema values were 1.2 percentage points higher among men compared with women and 0.7, 1.2, and 1.2 percentage points lower among African Americans, Hispanics, and Asians compared with whites, respectively (P , 0.001). Percent emphysema was positively related to age and height and inversely related to body mass index. The findings were similar for total lung volume on CT scans and for percent emphysema defined at 2910 Hounsfield units and measured on cardiac scans. Reference equations to account for these differences are presented for never, former and current smokers.Conclusions: Similar to lung function, percent emphysema varies substantially by demographic factors and body size among healthy never-smokers. The presented reference equations will assist in defining abnormal values for percent emphysema and total lung volume on CT scans, although validation is pending.

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“…However, only two studies with comparatively small sample sizes (22,436 and 8,033) included Asian participants, and neither of these studies is from People’s Republic of China. Only the normal range of LAA%(-960 HU),29 LAA%(-950 HU),29–31,34–39 LAA%(-912 HU),33 LAA%(-910 HU),36 Perc 15,29,35 and mean lung attenuation30,32,33,35,37 have been reported, and these indices are inadequate for differentiating ILD from poorly aerated normal lungs.…”

Section: Introductionmentioning

confidence: 99%

<p>Normal lung attenuation distribution and lung volume on computed tomography in a Chinese population</p>

Cheng

Pang

et al. 2019

COPD

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Backgroud and objectives: Although lung attenuation distribution and lung volume on computed tomography (CT) have been widely used in evaluating COPD and interstitial lung disease, there are only a few studies regarding the normal range of these indices, especially in Chinese subjects. We aimed to describe the normal range of lung attenuation distribution and lung volume based on CT. Methods: Subjects with normal lung function and basically normal chest CT findings (derivation group) at Ruijin Hospital, Shanghai (from January 2010 to June 2014) were included according to inclusion and exclusion criteria. The range of the percentage of lung volume occupied by low attenuation areas (LAA%), percentile of the histogram of attenuation values (Perc n), and total lung volume were analyzed. Relationships of these measures with demographic variables were evaluated. Participants who underwent chest CT examination for disease screening and had basically normal CT findings served as an external validation group. Results: The number of subjects in the derivation group and external validation groups were 564 and 1,787, respectively. Mean total lung volumes were 4,468±1,271 mL and 4,668±1,192 mL, and median LAA%(-950 HU) was 0.19 (0.03–0.43) and 0.17 (0.01–0.41), in the derivation and external validation groups, respectively. Reference equations for lung volume and attenuation distribution (LAA% using -1,000–210 HU, Perc 1 to Perc 98) were generated: Lung volume (mL) = -1.015 *10^4+605.3*Sex (1= male, 0= female)+92.61*Height (cm) –12.99*Weight (kg) ±1766; LAA% (-950 HU)=[0.2027+0.05926*Sex (1= male, 0= female) –4.111*10^-3*Weight (kg) +4.924*10^-3*Height (cm) +8.504*10^-4*Age]^7.341–0.05; Upper limit of normal range: [0.2027+0.05926*Sex-4.111*10^-3*Weight+4.924*10^-3*Height+8.504*10^-4*Age+0.1993]^7.341–0.05. Conclusion: This large population-based retrospective study demonstrated the normal range of LAA%, Perc n, and total lung volume measured on CT scans among subjects with normal lung function and CT findings. Reference equations are provided.

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Characterizing Functional Lung Heterogeneity in COPD Using Reference Equations for CT Scan-Measured Lobar Volumes

Cited by 12 publications

References 33 publications

Bronchoarterial ratio in never‐smokers adults: Implications for bronchial dilation definition

Bronchoarterial ratio in never‐smokers adults: Implications for bronchial dilation definition

Variation in the Percent of Emphysema-like Lung in a Healthy, Nonsmoking Multiethnic Sample. The MESA Lung Study

<p>Normal lung attenuation distribution and lung volume on computed tomography in a Chinese population</p>

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