Quantifying heterogeneity in emphysema from high-resolution computed tomography: a lung tissue research consortium study

TitleQuantifying heterogeneity in emphysema from high-resolution computed tomography: a lung tissue research consortium study
Publication TypeJournal Article
Year of Publication2013
AuthorsYilmaz C, Dane DM, Patel NC, Hsia CCW
JournalAcad Radiol
Volume20
Issue2
Pagination181-93
Date Published2013 Feb
ISSN1878-4046
KeywordsAdult, Aged, Algorithms, Emphysema, Female, Humans, Imaging, Three-Dimensional, Male, Middle Aged, Radiographic Image Enhancement, Radiographic Image Interpretation, Computer-Assisted, Radiography, Thoracic, Reproducibility of Results, Sensitivity and Specificity, Tomography, X-Ray Computed
Abstract

RATIONALE AND OBJECTIVES: To quantify spatial distribution of emphysema using high-resolution computed tomography (HRCT), we applied semiautomated analysis with internal attenuation calibration to measure regional air volume, tissue volume, and fractional tissue volume (FTV = tissue/[air + tissue] volume) in well-characterized patients studied by the Lung Tissue Research Consortium (LTRC).

METHODS: HRCT was obtained at supine end-inspiration and end-expiration, and prone end-inspiration from 31 patients with mild, moderate, severe, or very severe emphysema (stages II-V, forced expiratory volume at 1 second >75%, 51%-75%, 21%-50% and ≤20% predicted, respectively). Control data were from 20 healthy non-smokers (stage I). Each lobe was analyzed separately. Heterogeneity of FTV was assessed from coefficients of variation (CV) within and among lobes, and the kurtosis and skewness of FTV histograms.

RESULTS: In emphysema, lobar air volume increased up to 177% above normal except in the right middle lobe. Lobar tissue volume increased up to 107% in mild-moderate stages then normalized in advanced stages. Normally, FTV was up to 82% higher in lower than upper lobes. In mild-moderate emphysema, lobar FTV increased by up to 74% above normal at supine inspiration. In severe emphysema, FTV declined below normal in all lobes and positions in correlation with pulmonary function (P < .05). Markers of FTV heterogeneity increased steadily with disease stage in correlation with pulmonary function (P < .05); the pattern is distinct from that seen in interstitial lung disease (ILD).

CONCLUSION: CT-derived biomarkers differentiate the spatial patterns of emphysema distribution and heterogeneity from that in ILD. Early emphysema is associated with elevated tissue volume and FTV, consistent with hyperemia, inflammation or atelectasis.

DOI10.1016/j.acra.2012.09.013
Alternate JournalAcad Radiol
PubMed ID23122057
PubMed Central IDPMC3566303
Grant List1 RO3 HL097010 / HL / NHLBI NIH HHS / United States
1 UL1 RR024150 / RR / NCRR NIH HHS / United States
R01 HL040070 / HL / NHLBI NIH HHS / United States
R03 HL097010 / HL / NHLBI NIH HHS / United States