Use of 3D pseudo-continuous arterial spin labeling to characterize sex and age differences in cerebral blood flow

The aim of the present study is to use 3D pseudo-continuous arterial spin labeling (pCASL) to measure changes in normal cerebral blood flow (CBF) values with sex and age. Eighty subjects underwent magnetic resonance imaging study on a 3.0-T scanner. 3D pCASL was used to measure CBF. Estradiol and testosterone levels were also assessed. Based on sex and age, the subjects were divided into four groups for statistical analysis. CBF was higher in young premenopausal women than in young men (P < 0.01), while there was no difference in CBF between older postmenopausal women and older men. CBF was also significantly decreased in older postmenopausal women compared with young women (P < 0.01), whereas no such age-related effect was present in men. These observations indicate that sex and age differences are important considerations when studying nervous system diseases and that the age range and female-to-male ratio should be considered in the selection of subjects for brain studies in order to eliminate bias. Further, the normal CBF values assessed by pCASL provide a basis for further clinical use of pCASL.