Optimal velocity encoding during measurement of cerebral blood flow volume using phase-contrast magnetic resonance angiography

摘要

This study investigated the effect of velocity encoding on measurement of brain blood flow and blood volume of inflow and outflow using phase-contrast magnetic resonance angiography.A single two-dimensional phase-contrast magnetic resonance angiography slice was applied perpendicular to the internal carotid artery and the vertebral artery at C2 level.For each subject,the velocity encoding was set from 30 to 90 cm/s with an interval of 10 cm/s for a total of seven settings.Various velocity encodings greatly affected blood flow volume,maximal blood flow velocity and mean blood flow velocity in the internal carotid artery,but did not significantly affect vertebral arteries and jugular veins.When velocity encoding was 60-80 cm/s,the inflow blood volume was 655 ± 118 mL/min,and the outflow volume was 506 ± 186 mL/min.The ratio of outflow/inflow was steady at 0.78-0.83,and there was no aliasing in any of the images.These findings suggest that velocity encodings of 60-80 cm/s should be selected during measurement of cerebral blood flow volume using phase-contrast magnetic resonance angiography.