Radiomic Feature Spatially Characterizes the Transition of Normal Lung Parenchyma to Small Airways Disease in COPD.
Article
Overview
abstract
PURPOSE: Small airways disease (SAD), a major cause of airflow obstruction in COPD patients, has been identified as a precursor to emphysema. Nevertheless, there is a lack of clinical techniques that can quantify the progression of SAD. We aim to determine if our Parametric Response Mapping (PRM) method to quantify SAD offers insight into lung progression from healthy to emphysema. MATERIALS AND METHODS: PRM metrics quantifying normal lung (PRM Norm ) and functional SAD (PRM fSAD ) were generated from CT scans collected as part of the COPDGene study (n=8956). Volume density (V) and Euler-Poincaré Characteristic (χ) maps, measures of extent and coalescence of pocket formations, respectively, were determined for both PRM Norm and PRM fSAD . Association with COPD severity, emphysema, and spirometric measures were assessed via multivariable regression models. RESULTS: Across all GOLD, we observed a strong linear correlation between χ fSAD and χ Norm (ρ =-0.745, p<0.001). Values of χ fSAD and χ Norm were found to flip signs in unison between GOLD 2 and 4, demonstrating an inversion in parenchymal topology. For subjects with COPD, multivariable analysis showed that both χ fSAD (β of 0.106, p<0.001) and V fSAD (β of 0.065, p=0.004) were independently associated with FEV 1 % predicted. V and χ measures for PRM fSAD and PRM Norm were independently associated with the amount of emphysema. CONCLUSIONS: We demonstrated that χ of fSAD and Norm have independent value when associated with lung function and emphysema, even when considering the amount of each (i.e., V fSAD , V Norm ). Our approach for quantifying pocket formations of PRM fSAD from normal lung parenchyma (PRM Norm ) may show promise as a CT readout of emphysema onset.
