Range and variability of CBF in young adults: PC‐MRI and ASL studies

Several studies have compared phase contrast magnetic resonance imaging (PC‐MRI) with arterial spin labeling (ASL) in the same cohort of subjects. However, these earlier comparisons included subjects across a wide age range, which can contribute to increased intersubject variability. We compared the range and variability of CBF based on PC‐MRI and ASL in a group of young subjects. We also explored whether the comparison between PC‐MRI and ASL was dependent on sex. Thirty young subjects (17 females) were recruited in this study. The CBF from PC‐MRI (CBF PC ) was calculated as the total blood flow normalized to brain parenchyma mass. The CBF from ASL (CBF ASL ) was quantified based on the perfusion kinetic model. The ratio between CBF ASL and CBF PC was calculated. Females exhibited significantly higher CBF using both PC‐MRI ( p < 0.05) and ASL ( p < 0.005) compared with males. The disparity in CBF between sexes was more prominent in ASL measurements. A significant correlation was observed between CBF PC and CBF ASL values ( r = 0.47, p < 0.01), and CBF ASL tended to be lower than CBF PC values ( p < 0.001). This difference between CBF ASL and CBF PC was more pronounced in males, as evidenced by the smaller CBF ASL /CBF PC ratio in males ( p < 0.05). The measurement of global CBF with PC‐MRI and ASL are correlated, but CBF ASL exhibits lower values than CBF PC . As the underestimation of CBF ASL is prominent in males, ASL amplifies the sexual dimorphism in CBF compared with PC‐MRI.