Fully automatic quantification of pulmonary fat attenuation volume by CT: an exploratory pilot study in non-malignant chronic lung diseases.

<bold>Background:</bold> Lipid metabolism and deposition is altered in the lung of patients with fibrotic interstitial lung disease (fILD) and chronic obstructive pulmonary disease (COPD). This study was aimed at detecting lipids alterations by using computed tomography (CT)-based analysis of pulmonary fat attenuation volume (CTpfav) in patients with non-malignant chronic lung diseases. <bold>Methods:</bold> This observational retrospective single-center study included 716 chest CT scans from three subcohorts: fILD (n = 154), COPD (n = 283) and controls (n = 279). Fully automated quantification of CTpfav was based on lung segmentation and HU-thresholding. The pulmonary fat index (PFI) was derived by normalizing CTpfav to the CT lung volume. <bold>Results:</bold> Patients with fILDs demonstrated a significant increase in CTpfav (median 71.0 mL, interquartile range [IQR] 59.7 mL, p < 0.001) and PFI (median 1.9%, IQR 2.4%, p < 0.001) when compared to the control group (CTpfav median 43.6 mL, IQR 16.94 mL; PFI median 0.9%, IQR 0.5%). In contrast, individuals with COPD exhibited significantly reduced CTpfav (median 36.2 mL, IQR 11.4 mL, p < 0.001) and PFI (median 0.5%, IQR 0.2%, p < 0.001). <bold>Conclusion:</bold> The fully automated method for quantifying CTpfav might provide a new imaging marker for assessing chronic lung diseases like ILD and COPD in the clinical routine.