Fig. 1From: Counter-clockwise vortical blood flow in the main pulmonary artery in a patient with patent ductus arteriosus with pulmonary arterial hypertension: a cardiac magnetic resonance imaging case report4D flow evaluation of the PDA. Schematic 3D anatomy (a) of the PDA and surrounding cardiovascular structures based on 3D reconstruction of the anatomical phase contrast images. PDA length and time-averaged cross-sectional area at the center of the PDA were evaluated by multi-planar reformation. Time courses of maximal velocity (b) and net flow rate (c) across the central cross-section of the PDA demonstrate an early systolic and an early diastolic left-to-right peak and small right-to-left flow at end-systole. Velocity-color-encoded streamlines originating from PDA at early systole (d), end-systole (e) and early diastole (f) projected onto multi-planar reformatted anatomical images reflect these bi-phasic PDA flow characteristics. In early systole (d) and diastole (f) there is fast left-to-right flow through the PDA that reverses direction in the main pulmonary artery. In end-systole (e) blood spirals from right-to-left but no streamlines (and particles in Additional file 1: in the online-only Data Supplement) enter the aorta. PDA = patent ductus arteriosus; MPA = main pulmonary artery; RPA = right pulmonary artery; PV = pulmonary valve; AD = aorta descendens; AA = aorta ascendens, LV = left ventricle, RV = right ventricle, LA = left atriumBack to article page