Positron emission tomography (PET), one of the functional imaging modalities, visualizes the brain function based on the retention of radioisotope-labeled ligands. PET facilitates imaging of localized or diffuse metabolic disturbances responsible for cognitive impairment, and it is effective for differentiating vascular dementia (VaD) from degenerative dementia such as Alzheimer disease (AD). However, the confounding pathology and interaction between VaD and AD have become a focus of interest. Cerebrovascular disease and AD not only occur together but they also interact.
This review overviews the role of structural and functional imaging to diagnose vascular dementia, and summarizes the usefulness of PET to analyze the pathophysiology and differentially diagnose vascular dementia, using data on oxygen metabolism and amyloid accumulation in the brain.
In our study, cerebral cortical retention of Pittsburgh compound-B (11C-PIB) was noted in more than half of VaD patients. Various types of low perfusion of cerebral blood flow were observed in patients, but low perfusion areas were not associated with cortical PIB retention, and the oxygen extraction fraction (OEF) was increased in 3/5 of those with retention.
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