Correlation Between Brain 18F-AV45 and 18F-FDG PET Distribution Characteristics and Cognitive Function in Patients with Mild and Moderate Alzheimer’s Disease

Background: Florbetapir (AV45) and fluorodeoxyglucose (FDG) PET imaging are valuable techniques to detect the amyloid-β (Aβ) load and brain glucose metabolism in patients with Alzheimer’s disease (AD). Objective: The purpose of this study is to access the characteristics of Aβ load and FDG metabolism in brain for further investigating their relationships with cognitive impairment in AD patients. Methods: Twenty-seven patients with AD (average 70.6 years old, N = 13 male, N = 14 female) were enrolled in this study. These AD patients underwent the standard clinical assessment and received detailed imaging examinations of the nervous system by using Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MOCA), 18F-AV45, and 18F-FDG PET scans. Results: Of 27 AD patients, 22 patients (81.5%) showed significantly increases in Aβ load and 26 patients (96.3%) had significantly reductions in FDG metabolism. The moderate AD patients had more brain areas of reduced FDG metabolism and more severe reductions in some regions compared to mild AD patients, with no differences in Aβ load observed. Moreover, the range and degree of reduced FDG metabolism in several regions were positively correlated with the total score of MMSE or MOCA, whereas the range of Aβ load did not. No correlation was found between the range of Aβ load and the range of reduced FDG metabolism in this study. Conclusion: The reduction in FDG metabolisms captured by 18F-FDG imaging can be used as a potential biomarker for AD diagnosis in the future. 18F-AV45 imaging did not present valuable evidence for evaluating AD patient in this study.