B23-20 Quantitative CT Detects Changes in Parenchymal, Airway and Vascular Features in Familial Pulmonary Fibrosis Relatives With Interstitial Lung Abnormalities

Abstract Rationale First degree relatives of patients with familial pulmonary fibrosis (FPF) have an increased risk of developing interstitial lung disease (ILD). Interstitial lung abnormalities (ILA), incidentally detected changes visible on chest HRCT which might precede clinical disease, remain incompletely characterized in this population. We sought to objectively characterize airway, vascular, and parenchymal features in FPF relatives with and without ILA using quantitative CT (qCT) analysis. Methods The cohort consisted of first-degree relatives of patients with FPF who received at least one research HRCT at Vanderbilt University Medical Center (VUMC) as part of a longitudinal cohort study. Scans were adjudicated visually for the presence or absence of ILA and ILD; subjects with extensive ILA (meeting ILD criteria in this cohort) were excluded. Deidentified CT Images with thin (1.5 mm) sections and sharp reconstruction kernels were analyzed by FLUIDDA (Kontich, Belgium) using a fully-automated pipeline with manual quality checks. Parameters reflecting the volumes and morphology of pulmonary vessels and airways, and measurements of parenchymal texture and density were produced. Unpaired student’s T-test were used to test each qCT parameter for difference between subjects with and without ILA. Results 227 subjects (47 with ILA, 180 without) had suitable HRCT at their first visit. Mean age was 58.13 (8.68) for subjects with ILA and 51.36 (8.74) for those without; 57% of each group was female. Parameters which differed significantly (p 0.05) between groups or trended towards significance (p 0.1) were the volume of vessels 5-10 mm2 in cross-sectional area (BV5-10, p = 0.06), total vascular volume normalized to total lung volume (p = 0.008), airway volume normalized to total lung volume (p = 0.099), the percentage of lung voxels with attenuation -600 HU (p = 0.04), quantitative fibrosis volume in ml (p = 0.04) and normalized to total lung volume (p = 0.02), and mean lung density (p = 0.04). Conclusion In this cohort of first-degree relatives of patients with FPF, ILA are characterized by changes to vascular and vessel-like structures, airway volumes, lung density, parenchymal texture, which may be observed using qCT. Future research will evaluate whether these or other qCT parameters may be predictive of and best quantify ILA progression. This abstract is funded by: ThreeLakes Foundation, NHLBI