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Parametric Response Mapping Monitors Temporal Changes on Lung CT Scans in the Subpopulations and Intermediate Outcome Measures in COPD Study (SPIROMICS)
Journal article   Peer reviewed

Parametric Response Mapping Monitors Temporal Changes on Lung CT Scans in the Subpopulations and Intermediate Outcome Measures in COPD Study (SPIROMICS)

Jennifer L Boes, Benjamin A Hoff, Maria Bule, Timothy D Johnson, Alnawaz Rehemtulla, Ryan Chamberlain, Eric A Hoffman, Ella A Kazerooni, Fernando J Martinez, Meilan K Han, …
Academic radiology, Vol.22(2), pp.186-194
02/2015
DOI: 10.1016/j.acra.2014.08.015
PMCID: PMC4289437
PMID: 25442794
url
https://www.ncbi.nlm.nih.gov/pmc/articles/4289437View
Open Access

Abstract

The longitudinal relationship between regional air trapping and emphysema remains unexplored. We have sought to demonstrate the utility of parametric response mapping (PRM), a computed tomography (CT)–based biomarker, for monitoring regional disease progression in chronic obstructive pulmonary disease (COPD) patients, linking expiratory- and inspiratory-based CT metrics over time. Inspiratory and expiratory lung CT scans were acquired from 89 COPD subjects with varying Global Initiative for Chronic Obstructive Lung Disease (GOLD) status at 30 days (n = 13) or 1 year (n = 76) from baseline as part of the Subpopulations and Intermediate Outcome Measures in COPD Study (SPIROMICS) clinical trial. PRMs of CT data were used to quantify the relative volumes of normal parenchyma (PRMNormal), emphysema (PRMEmph), and functional small airways disease (PRMfSAD). PRM measurement variability was assessed using the 30-day interval data. Changes in PRM metrics over a 1-year period were correlated to pulmonary function (forced expiratory volume at 1 second [FEV1]). A theoretical model that simulates PRM changes from COPD was compared to experimental findings. PRM metrics varied by ∼6.5% of total lung volume for PRMNormal and PRMfSAD and 1% for PRMEmph when testing 30-day repeatability. Over a 1-year interval, only PRMEmph in severe COPD subjects produced significant change (19%–21%). However, 11 of 76 subjects showed changes in PRMfSAD greater than variations observed from analysis of 30-day data. Mathematical model simulations agreed with experimental PRM results, suggesting fSAD is a transitional phase from normal parenchyma to emphysema. PRM of lung CT scans in COPD patients provides an opportunity to more precisely characterize underlying disease phenotypes, with the potential to monitor disease status and therapy response.
Computed Tomography parametric response map small airways disease Chronic obstructive pulmonary disease disease progression voxel-wise analysis diagnostic imaging

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