Amyloid imaging with 11C-PIB PET/CT and glucose metabolism with 18F-FDG PET/CT in a study on cognitive impairment in the clinical setting

The objective of this study was to evaluate the contribution of amyloid imaging with 11C-Pittsburgh compound B (11C-PIB) and of glucose metabolism on 18F-fluorodeoxyglucose (18F-FDG) PET/CT to the study of cognitive impairment in the clinical setting. Thirty-four patients (15 male, 19 female) were enrolled in the study. They were classified according to their clinically presented symptoms. Six patients had subjective memory complaints, five had nonamnestic mild cognitive impairment (MCI), seven had amnestic MCI, seven had prodromal Alzheimer’s disease (AD), five had frontotemporal dementia, two had dementia with Lewy bodies, and two had cortical degeneration. All the scans were conducted to determine the likelihood of AD or to differentiate between AD and other dementia. Static 30-min 11C-PIB and 15-min 18F-FDG PET/CT scans were obtained. A visual analysis of images was performed. Three of the six patients with subjective memory complaints had positive 11C-PIB scans and one of them also had 18F-FDG hypometabolism. All five nonamnestic MCI patients had normal 11C-PIB and 18F-FDG. Four of the seven amnestic MCI patients showed 11C-PIB cortical retention but only one had positive 18F-FDG. Positive 11C-PIB and 18F-FDG were detected in five of the seven prodromal AD patients. All the five patients with FDT had positive 18F-FDG scans, but only one of the five had 11C-PIB cortical retention. Both dementia with Lewy bodies and cortical degeneration patients had positive 11C-PIB and 18F-FDG scans. The combined use of 11C-PIB and 18F-FDG PET provides relevant information for the clinical management of cognitive impairment. The detection of positive 11C-PIB cortical retention in patients may be an indicator of the need for further clinical assessment and monitoring.