PWV determination. A, a sagittal gradient-echo image of the aorta is shown. Velocity-encoded MRI is performed perpendicular to the aorta at two levels: site one is positioned at the level of the pulmonary trunk; site two is positioned at the distal descending abdominal aorta 7.5 cm below the diaphragm; Δx1: path length of the aortic arch Δx2: path length of the descending aorta. B, the flow curves of the ascending, proximal and distal descending aorta are shown; Δt1 and Δt2 denote the transit-time between the arrival of the pulse wave at subsequent measurement sites. Aortic PWV is defined as Δx/Δt (m/s).