Figure 1From: Effects of age and smoking on endothelial function assessed by quantitative cardiovascular magnetic resonance in the peripheral and central vasculature CMR-based femoral artery blood-flow velocity measurement: a) gray-scale magnitude image showing femoral artery and vein; b) time-resolved velocity (temporal resolution, 20Â ms) in the femoral artery at baseline and, c) during hyperemia (temporal resolution, 120Â ms). Projection images in (b) display velocity as a function of time for three heart beats, and plots below represent averages across arterial lumen showing normal tri-phasic waveform, with peak systolic velocity, Vs, peak retrograde velocity, Vr, and peak antegrade velocity, Va, indicated. Dashed line defines the zero velocity. During hypermia after cuff release (c) velocity is elevated indicating forward flow only, returning to baseline after approximately 15Â s. Horizontal black arrow in (c) marks the forward flow duration (i.e. period of hyperemia, TFF).Back to article page