Increased regional ventilation as early imaging marker for future disease progression of interstitial lung disease: a feasibility study

Objectives Idiopathic pulmonary fibrosis (IPF) is a disease with a poor prognosis and a highly variable course. Pathologically increased ventilation-accessible by functional CT-is discussed as a potential predecessor of lung fibrosis. The purpose of this feasibility study was to investigate whether increased regional ventilation at baseline CT and morphological changes in the follow-up CT suggestive for fibrosis indeed occur in spatial correspondence. Methods In this retrospective study, CT scans were performed at two time points between September 2016 and November 2020. Baseline ventilation was divided into four categories ranging from low, normal to moderately, and severely increased (C1-C4). Correlation between baseline ventilation and volume and density change at follow-up was investigated in corresponding voxels. The significance of the difference of density and volume change per ventilation category was assessed using paired t-tests with a significance level of p <= 0.05. The analysis was performed separately for normal (NAA) and high attenuation areas (HAA). Results The study group consisted of 41 patients (73 +/- 10 years, 36 men). In both NAA and HAA, significant increases of density and loss of volume were seen in areas of severely increased ventilation (C4) at baseline compared to areas of normal ventilation (C2, p < 0.001). In HAA, morphological changes were more heterogeneous compared to NAA. Conclusion Functional CT assessing the extent and distribution of lung parenchyma with pathologically increased ventilation may serve as an imaging marker to prospectively identify lung parenchyma at risk for developing fibrosis.

Automated summary

This study aimed to investigate the correlation between increased ventilation at baseline CT and morphological changes suggestive of fibrosis in follow-up CT. The results showed significant density increases and volume loss in areas of severely increased ventilation, particularly in high attenuation areas.