Abstract 12827: Alterations in Flow Patterns and Wall Shear Stress in Pulmonary Artery Visualized With Phase-resolved 3D Cine Phase Contrast MRI (4D-Flow) in Patients With Systemic Sclerosis

Abstract

Background: The pulmonary circulation is impaired in patients with systemic sclerosis (SSc), and the analysis of pulmonary arterial (PA) blood flow has a great clinical significance. Using 4D-Flow, we studied the changes in PA blood flow velocity vectors and wall shear stress (WSS) in SSc patients. Methods: Twenty one SSc patients (M/F: 1/20, 56±15 years) including 2 PA hypertension, and 7 control subjects underwent 4D-Flow. We set planes traversing the main and first branches of PA, and the velocity vectors were post-processed to delineate streamline images. WSS images were obtained at the surface of PA. The plane-averaged flow velocity at the main PA, surface-averaged WSS, and oscillatory shear index (OSI), the %WSS acting in other directions from the mean WSS vector during a cardiac cycle, were compared. Results: (1) The PA flow showed laminar flow pattern at the early systolic phase in all patients and subjects, but diffuse helical flow in 11 SSc patients (right upper), focal helical flow in 6 SSc patients and 2 control subjects at the late systolic to early diastolic phase. The other 4 SSc patients and 5 control subjects had continuous laminal flow (left upper). (2) The peak systolic PA flow velocity did not differ between them, whereas the diastolic flow velocity was significantly greater in SSc patients (minimum velocity; 26±24 mm/sec vs. -26±52 mm/sec, p<0.01). (3) WSS at the peak systolic flow velocity was significantly lower and spatially heterogeneous in SSc patients (lower figs; 1.1±0.2 Pa vs. 1.4±0.4 Pa, p<0.01). Both WSS at the diastolic phase and OSI were significantly greater in SSc patients (minimum WSS; 0.28±0.07 Pa vs. 0.19±0.04 Pa, p<0.01, OSI; 0.14±0.03% vs. 0.09±0.02%, p<0.05). Conclusions: The 4D-Flow disclosed the different PA flow patterns between SSc patients and control subjects. In SSc patients, WSS at the PA was generally decreased and varied spatially and temporally. 4D-Flow has a potential to detect the subclinical changes of PA flow dynamics in SSc.