Fig. 2.

Example waveforms from internal carotid artery. a Pulsatility index was calculated as the difference between systolic maximum and diastolic minimum flow rates divided by the mean flow rate. b Flow volume pulsatility (FVP) was calculated as the cumulative integral of the blood flow rate waveform after subtraction of the mean flow rate. FVP was defined as the difference between the systolic maximum and the diastolic minimum volumes. The curve has been shifted vertically, so that minimum volume corresponds to zero. Both measures were further standardized by R–R interval