Research articlePerformance of computed tomography-derived pulmonary vasculature metrics in the diagnosis and haemodynamic assessment of pulmonary arterial hypertension

- PA/Ao, PVD and %CSA<5 are useful noninvasive metrics for the pulmonary vasculature.
- A high diameter of pulmonary artery to aorta ratio predicted existence of PAH.
- %CSA<5, especially of the upper slice, may reflect hemodynamics in PAH.
- Combined use of PA/Ao, PVD, and %CSA<5 best predicted hemodynamics in PAH.

BackgroundFew studies have addressed the value of combining computed tomography-derived pulmonary vasculature metrics for the diagnosis and haemodynamic evaluation of pulmonary arterial hypertension (PAH).Materials and methodsWe measured three computed tomography parameters for the pulmonary artery, peripheral vessels, and pulmonary veins: the ratio of the diameter of the pulmonary artery to the aorta (PA/Ao), the cross-sectional area of small pulmonary vessels <5 mm2 as a percentage of total lung area (%CSA<5), and the diameter of the right inferior pulmonary vein (PVD). The measured quantities were compared between patients with PAH (n = 45) and control subjects (n = 56), and their diagnostic performance and associations with PAH-related clinical indices, including right heart catheterization measurements, were examined.ResultsPA/Ao and %CSA<5 were significantly higher in patients with PAH than in controls. Receiver-operating characteristic curve analysis for ability to diagnose PAH showed a high area under the curve (AUC) for PA/Ao (0.95) and modest AUCs for %CSA<5 (0.75) and PVD (0.56). PA/Ao correlated positively with mean pulmonary arterial pressure and PVD correlated negatively with pulmonary vascular resistance. The %CSA<5 correlated negatively with mean pulmonary arterial pressure and pulmonary vascular resistance and positively with cardiac index. Notably, the PA/Ao and PVD values divided by %CSA<5 correlated better with right heart catheterization indices than the non-divided values.ConclusionPA/Ao, %CSA<5, and PVD are useful non-invasive pulmonary vasculature metrics, both alone and in combination, for diagnosis and haemodynamic assessment of PAH.