Characterization of CT-Derived Pulmonary Vascular Abnormalities Associated with Pulmonary Hypertension in Chronic Lung Disease.

Abstract

Pulmonary vascular remodeling is implicated in the pathophysiology of pulmonary hypertension (PH) in chronic lung diseases. Computed tomography (CT) metrics of pulmonary vessels may provide insight into the impact of vessel morphology on PH severity in chronic lung diseases (CLD). Are CT-assessed pulmonary vascular abnormalities associated with the presence and severity of PH in chronic obstructive pulmonary disease (COPD) and fibrosing interstitial lung disease (ILD), and how are they related to parenchymal damage? We evaluated 117 patients with CLD (63 with COPD and 54 with ILD), and 38 subjects with idiopathic pulmonary arterial hypertension as a comparator group. Patients with COPD and ILD were stratified according to the presence and severity of PH using right heart catheterization. Pulmonary vessel volumes, stratified in arteries and veins, and the extent of emphysema and fibrosis were assessed by volumetric, non-contrast chest CT scans. Patients with COPD exhibited greater vascular and lung volumes than those with ILD, although they showed lower small-vessel volume when adjusted for lung volume. In both diseases, severe PH was associated with a reduced volume of small arteries normalized to total arterial volume (BV5art/TAV), more pronounced in COPD, who also showed larger central vessel volumes. In COPD, the extent of emphysema did not correlate with either hemodynamic impairment or small-vessel volume. In contrast, in ILD, the extent of fibrosis was unrelated to hemodynamic impairment but was inversely corelated with the volume of small arteries and veins. COPD and fibrosing ILD exhibit marked differences in pulmonary vessel morphology and their relationship with parenchymal remodeling, suggesting distinct mechanisms underlying PH development. In lung disease, the BV5art/TAV ratio appears to be a sensitive marker of hemodynamically confirmed severe PH, particularly in COPD, reflecting intravascular volume redistribution due to peripheral vessel remodeling.