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

Purpose Positron emission tomography (PET) imaging with amyloid-beta (A beta) tracers and 2-[18F] fluoro-2-Deoxy-d-glucose (F-18-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 A beta 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 A beta-PET (F-18-florbetapir or F-18-florbetaben) scan is comparable to that of a F-18-FDG PET scan, independent of disease state. Method A partial correlation was performed on early-frame F-18-florbetapir and F-18-FDG regional data from 100 participants. In a secondary analysis, we compared 92 F-18-florbetapir and 21 F-18-florbetaben early-frame A beta scans from cognitively unimpaired and mild cognitive impairment participants to ascertain if regional early-frame information was similar across different A beta-PET radioligands. Results The partial correlation of early-frame F-18-florbetapir with F-18-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 F-18-florbetapir and F-18-florbetaben images. Conclusion Overall, we find that the regional uptake measurements from early-frame F-18-florbetapir are strongly correlated with regional glucose metabolism as measured in ground-truth F-18-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.