Fig. 1

a Maximum velocity-time graph following ROI placement on the cerebral aqueduct in phase-contrast images obtained [positive values (diastolic) show CSF flow velocity in the caudocranial direction and negative values (systolic) CSF flow velocity in the craniocaudal direction]. b CSF flow data [stroke volume (ml), forward flow volume (ml), backward flow volume (ml), regurgitant fraction (%), absolute stroke volume (ml), mean flux (ml/s), stroke distance (cm), and mean velocity (cm/s)] calculated for one cardiac beat by 2D-Q Flow software [16]