Fig. 5
From: Cerebral arterial flow dynamics during systole and diastole phases in young and older healthy adults
Flow chart of image acquisition and calculation of amplitude-related parameters of the arterial flow curve. (A) Sagittal three-dimensional angiography is used as a reference to position the intracranial (blue line) and extracranial (green line) acquisition planes. (B) Phase-contrast images in the intracranial acquisition plane were used to quantify flow in the right and left internal carotid arteries (ICAs_intra) and the basilar artery (BA). (C) Phase-contrast images in the extracranial acquisition plane were used to quantify flow in the right and left internal carotid arteries (ICAs_extra) and the right and left vertebral arteries (VAs). (D) The sum of the flows in the ICAs_extra (Q_ICAs_extra) and VAs (Q_VAs) is equal to the total extracranial arterial flow (Qa_total_extra). Similarly, the sum of the flows in the ICAs_intra (Q_ICAs_intra) and BA (Q_BA) is equal to the total intracranial arterial flow (Qa_total_intra). The parameter β is calculated by dividing the mean value of the arterial flow at the extracranial level by that at the intracranial level. (E) An example of the arterial flow curve shape in a healthy young volunteer. The upstroke acceleration parameter is estimated from the flow amplitude and the time between the baseline and the systolic peak