Quantification of Arterial and Venous Morphological Markers in Pulmonary Arterial Hypertension Using Computed Tomography.

BACKGROUND: Pulmonary hypertension is a heterogeneous disease and a significant portion of patients at risk for it have available computed tomography (CT) imaging. Advanced automated processing techniques could be leveraged to for early detection, screening and development of quantitative phenotypes. Pruning and vascular tortuosity have been previously described in pulmonary arterial hypertension (PAH) but the extent of these phenomena in arterial versus venous pulmonary vasculature and in exercise pulmonary hypertension (ePH) have not been described.

RESEARCH QUESTION: What are the arterial and venous manifestations of pruning and vascular tortuosity using CT imaging in PAH and do they also occur in ePH?

STUDY DESIGN AND METHODS: A cohort of patients with PAH, ePH and controls with available CT angiograms were retrospectively identified to examine the differential arterial and venous presence of pruning and tortuosity in patients with precapillary pulmonary hypertension not confounded by lung or thromboembolic disease The pulmonary vasculature was reconstructed, an AI method was used to separate arteries and veins and used to compute arterial and venous vascular volumes and tortuosity.

RESULTS: 42 PAH, 12 ePH, 37 controls were identified. There was relatively lower arterial small vessel volume in subjects with PAH (PAH: 14.7(11.7-16.2) p<0.0001 vs controls 16.9(15.6-19.2)) and venous small vessel volume in subjects with PAH and ePH (PAH: 8.0(6.5-9.6) p<0.0001, ePH:7.8(7.5-11.4) p=0.004 vs control 11.5(10.6-12.2)). Higher large arterial volume, however, was only observed in the pulmonary arteries (PAH: 17.1(13.6-23.4) p<0.0001 vs controls 11.4(8.1-15.4)). Similarly, tortuosity was higher in the pulmonary arteries in PAH (PAH: 3.5(3.3-3.6) p=0.0002, vs control 3.2(3.2-3.3).

INTERPRETATION: Lower small distal pulmonary vascular volume, higher proximal arterial volume and higher arterial tortuosity are observed and can be quantified using automated techniques from clinically acquired CT scans of patients with exercise and resting pulmonary arterial hypertension.