Regional uptakes from early-frame amyloid PET and 18F-FDG PET scans are comparable independent of disease state.

ABSTRACT

PURPOSE: Positron emission tomography (PET) imaging with amyloid-beta (Aß) tracers and 2-[18F] fluoro-2-Deoxy-D-glucose (18F-FDG) is extensively employed in Alzheimer's disease (AD) studies as biomarkers of AD pathology and neurodegeneration. To reduce cost and additional burdens to the patient, early-frame uptake during Aß PET scanning has been proposed as a surrogate measure of regional glucose metabolism. Considering the disease state specific impact of AD on neurovascular coupling, we investigated to what extent the information captured in the early frames of an Aß-PET (18F-florbetapir or 18F-florbetaben) scan is comparable to that of a 18F-FDG PET scan, independent of disease state. METHOD: A partial correlation was performed on early-frame 18F-florbetapir and 18F-FDG regional data from 100 participants. In a secondary analysis, we compared 92 18F-florbetapir and 21 18F-florbetaben early-frame Aß scans from cognitively unimpaired and mild cognitive impairment participants to ascertain if regional early-frame information was similar across different Aß-PET radioligands. RESULTS: The partial correlation of early-frame 18F-florbetapir with 18F-FDG was significant in all 84 brain ROIs, with correlation values ranging from 0.61 to 0.94. There were no significant differences between early-frame 18F-florbetapir and 18F-florbetaben images. CONCLUSION: Overall, we find that the regional uptake measurements from early-frame 18F-florbetapir are strongly correlated with regional glucose metabolism as measured in ground-truth 18F-FDG PET scans, regardless of disease state. Future studies should focus on longitudinal early-frame amyloid PET imaging studies to further assess the value of early-frame imaging as a marker of brain metabolic decline.