Statistical maps of cerebral blood flow deficits in Alzheimer's disease

Images of cerebral blood flow or metabolism are useful as adjunct to the di fferential diagnosis of cortical dementia. The aim of this study was to cre ate statistical objective voxel maps of significant differences in regional cerebral blood flow between patients with Alzheimer's disease and age-matc hed healthy volunteers. Maps of significantly reduced cerebral blood flow w ere created based on a spatially normalized distribution of cerebral blood flow, measured with O-15-water and positron emission tomography in 16 Alzhe imer's patients, compared to 16 healthy age-matched volunteers. After Spati al normalization of voxel counts, the t-statistic of the cerebral blood flo w deficit was determined from the local voxel-SDs. In the patients, signifi cant reduction (P < 0.05) of the flow distribution was present in regions n ear the hippocampus, extending rostrally to the temporo-parietal region in both hemispheres, including the medial parietal cortex plus smaller frontal areas. The maximum reduction occurred in the left tapetum/hippocampus (53% , P = 0.061). In conclusion, statistical maps of cerebral blood flow defici ts objectively reveal the location of deficits, identifying areas that are difficult to identify by subjective visual inspection of conventional secti ons of cerebral blood flow maps. This is particularly well illustrated by t he pronounced flow reduction of the medial parietal cortices.