title: Separating function from structure in perfusion imaging of the aging brain.
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 PVE-correction algorithm was applied on the CBF images acquired with spin-echo EPI continuous arterial spin labeling MRI (voxel size = 3.4 x 3.4 x 8 mm(3)). Tissue-specific 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, PVE-corrected gray matter CBF was 88.2 +/- 16.1 and 107.3 +/- 17.5 mL/100 g min(-1) 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 age-related CBF difference between men and women, respectively. The GM-to-WM 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.
authors.affiliation: Program for Imaging and Cognitive Sciences in the Department of Radiology, Columbia University, New York, New York, USA. ia2026@columbia.edu
authors.forename: Iris
authors.initials: I
authors.lastname: Asllani
authors.forename: Christian
authors.initials: C
authors.lastname: Habeck
authors.forename: Ajna
authors.initials: A
authors.lastname: Borogovac
authors.forename: Truman R
authors.initials: TR
authors.lastname: Brown
authors.forename: Adam M
authors.initials: AM
authors.lastname: Brickman
authors.forename: Yaakov
authors.initials: Y
authors.lastname: Stern
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000473:pathology*; D000465:Algorithms; D001284:Atrophy / Q000209:etiology / Q000473:pathology* / Q000503:physiopathology; D001921:Brain / Q000098:blood supply / Q000473:pathology* / Q000503:physiopathology; D002545:Brain Ischemia / Q000473:pathology / Q000503:physiopathology; D001931:Brain Mapping / Q000379:methods; D002536:Cerebral Arteries / Q000473:pathology / Q000503:physiopathology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D002561:Cerebrovascular Disorders / Q000473:pathology* / Q000503:physiopathology; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012727:Sex Characteristics; D055815:Young Adult