Abstract
The accuracy of cerebral blood flow (CBF) imaging in humans has been impeded by the partial volume effects (PVE), which are a consequence of the limited spatial resolution. Because of brain atrophy, PVE can be particularly problematic in imaging the elderly and can considerably overestimate the CBF difference with the young. The primary goal of this study was to separate the structural decline from the true CBF reduction in elderly. To this end, a PVEโcorrection algorithm was applied on the CBF images acquired with spinโecho EPI continuous arterial spin labeling MRI (voxel size = 3.4 ร 3.4 ร 8 mm^3^). Tissueโspecific CBF images that were independent of voxels' tissue fractional volume were obtained in elderly (N = 30) and young (N = 26); mean age difference was 43 years. Globally, PVEโcorrected gray matter CBF was 88.2 ยฑ 16.1 and 107.3 ยฑ 17.5 mL/100 g min^โ1^ in elderly and young, respectively. The largest PVE contribution was found in the frontal lobe and accounted for an additional 10% and 12% increase in the ageโrelated CBF difference between men and women, respectively. The GMโtoโWM CBF ratios were found to be on average 3.5 in elderly and 3.9 in young. Whole brain voxelwise comparisons showed marked CBF decrease in anterior cingulate (bilateral), caudate (bilateral), cingulate gyrus (bilateral), cuneus (left), inferior frontal gyrus (left), insula (left), middle frontal gyrus (left), precuneus (bilateral), prefrontal cortex (bilateral), and superior frontal gyrus (bilateral) in men and amygdala (bilateral), hypothalamus (left), hippocampus (bilateral), and middle frontal gyrus (right) in women. Hum Brain Mapp 2009. ยฉ 2009 WileyโLiss, Inc.