Regional hypoxic cerebral vasodilation facilitated by diameter changes primarily in anterior versus posterior circulation

The inability to quantify cerebral blood flow and changes in macrocirculation cross-sectional area in all brain regions impedes robust insight into hypoxic cerebral blood flow control. We applied four-dimensional flow magnetic resonance imaging to quantify cerebral blood flow (ml • min−1) and cross-sectional area (mm2) simultaneously in 11 arteries. In healthy adults, blood pressure, O2 Saturation (SpO2), and end-tidal CO2 were measured at baseline and steady-state hypoxia (FiO2 = 0.11). We investigated left and right: internal carotid, vertebral, middle, anterior, posterior cerebral arteries, and basilar artery. Hypoxia (SpO2 = 80±2%) increased total cerebral blood flow from 621±38 to 742±50 ml • min−1 (p