Serial quantitative CT volume change in fibrotic interstitial lung disease: associations with mortality, acute exacerbation, and pulmonary function decline

Abstract Purpose To evaluate whether serial quantitative computed tomography (CT) volume change is associated with mortality, acute exacerbation, and concurrent pulmonary function decline in fibrotic interstitial lung disease. Materials and methods This retrospective single-center study included 102 participants who underwent surgical lung biopsy and paired CT between October 2018 and August 2023. A deep learning-based quantitative CT system measured fibrotic lesion and normal-lung volumes. Spearman correlations compared CT measures. Cox models assessed baseline volumes and annualized changes; linear models assessed concurrent pulmonary function change. Results Median age was 65 years [interquartile range, 56–69]; 68 participants were men. During median 4.82 years of follow-up, 12 deaths and 15 acute exacerbations occurred. Fibrotic lesion and normal-lung volumes were inversely correlated at baseline and follow-up, as were their annualized changes (ρ = −0.53, − 0.60, and − 0.56, respectively). Annualized fibrotic lesion volume increase (hazard ratio per 100 mL/year, 1.40; 95% confidence interval 1.15–1.69; q = 0.0036) and annualized normal-lung volume loss (hazard ratio per 500 mL/year decrease, 1.57; 95% confidence interval 1.20–2.06; q = 0.0036) were associated with death. Baseline fibrotic lesion volume was associated with acute exacerbation (hazard ratio per 100 mL, 1.33; 95% confidence interval 1.09–1.63; q = 0.012). Greater fibrotic lesion increase and normal-lung loss were associated with forced vital capacity decline; diffusing capacity associations were not significant after correction. Conclusion Serial quantitative CT volume change was associated with mortality and concurrent forced vital capacity decline, whereas baseline fibrotic lesion burden was associated with acute exacerbation in fibrotic interstitial lung disease.