18F-FDG and 18F-Florbetapir PET in Clinical Practice Regional Analysis in Mild Cognitive Impairment and Alzheimer Disease

Objective: The aim of this study is to compare regional cerebral metabolic rate of glucose metabolism and amyloid-beta density in patients with Alzheimer disease (AD), mild cognitive impairment (MCI), and healthy elderly subjects. Methods: Eighteen patients (including 6 AD, 5 amnestic MCI, and 7 controls) were enrolled at the University Hospital of Tours, France, and submitted to clinical, neuropsychological, and MRI examinations. PET images using F-18-florbetapir (266 MBq) and F-18-FDG (185 MBq) were acquired. SUV ratios in specific regions were defined using PMOD3.2 software. Results: The mean values of F-18-FDG SUV ratio were significantly lower in frontal, anterior cingulate, and temporal regions in MCI patients than in normal elderly (-15%, -22%, and -11%, respectively). Alzheimer disease patients showed global cerebral metabolic rate of glucose metabolism decrease, especially in parietal and precuneus regions (-15% and -13% compared with healthy control subjects). Only precuneus cortex showed an increased F-18-florbetapir uptake in AD. There was no other significant regional difference in the amyloid-beta density. Conclusions: In this study, we observed regional brain metabolic changes between MCI, AD, and controls, whereas only precuneus showed an increased amyloid-beta density in AD. F-18-florbetapir PET analysis needs to be visual and global, whereas F-18-FDG analysis can be regional.