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

Abstract

AbstractBackgroundIn the assessment of Alzheimer’s disease (AD), it is important to consider multiple aspects of the pathology, including amyloid burden and glucose metabolism. Currently, these two aspects require two separate PET scans, which is expensive and exposes the patient to multiple radioligand injections. To circumvent this issue, early‐frame uptake during amyloid PET imaging has been proposed as a surrogate measure of regional metabolism. Given the impact of disease on neurovascular coupling, we investigated whether the information captured in the early frames of an amyloid PET scan is comparable to that of a 18F‐FDG PET scan, independent of disease state.MethodEarly frame 18F‐AV45 and 18F‐FDG PET scans from 103 participants ‐ 54 Cognitively Unimpaired (CU), 40 MCI, 17 Dementia ‐ were obtained from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) database and standard uptake values for 82 regions of interest were extracted from each image. A partial correlation with time between scans as a covariate was performed, along with a linear regression to assess the R2 value and any potential effects of disease state and interaction between FDG and disease state.ResultThe partial correlation was significant in 70/82 ROIs. The highest correlation between the amyloid and 18F‐FDG data in a cortical region was in the anterior temporal lobe (left: β=0.41, p=6.01e‐5; right:β=0.41, p=7.4e‐5). Compared to CU participants, the early‐frame AV45 versus FDG uptake association in Dementia participants was significantly stronger in the bilateral amygdala (left:β=‐0.42, p=0.049; right:β=‐0.58, p=0.007), anterior temporal lobe (left:β=‐0.38, p=0.003; right:β=‐0.29, p=0.02), and caudate (left:β=‐0.32, p=0.046; right:β=‐0.43, p=0.0006), and the right inferiorlateral remainder of the parietal lobe (β=‐0.39, p=0.03), but weaker in right lingual gyrus (β=0.64, p=0.02).ConclusionOverall, we find that the early‐frame amyloid scans largely capture the same information about metabolism as 18F‐FDG PET scans do, regardless of disease state. The regions with significant difference between disease states are implicated in Dementia pathophysiology and warrant longitudinal early‐frame amyloid PET imaging studies to further assess the value of early‐frame imaging as a marker of brain metabolism.