Methodology dependent sex differences in Aβ‐PET measured with SUVR

Background Determining Aβ-PET status is crucial for Alzheimer’s disease trials. Standard uptake value ratio (SUVR) using a reference region common semi-quantitative technique. Sex differences in regional blood flow and white matter (WM) could impact SUVR differentially depending on the region. It important to understand how methodological factors can influence derived Aβ status. Method Individuals from Insight 46 (1946 British birth cohort) underwent PET/MR scanning with [18F]florbetapir (N = 425; mean age (SD) 70.6 (0.7); 49% female). Regions T1-weighted MRI geodesic information flows (GIF) were resampled PET space. was calculated (50-60 mins post-injection) cortical composite target normalised whole cerebellum (WC) or eroded WM, with/without partial volume correction (PVC). Additionally, SUV normalising injected dose weight. Distribution (DVR) Logan graphical analysis (cerebellar grey reference) N 391 (51% Linear regression used investigate measures by sex adjusting volumes. defined Gaussian-mixture modelling. DVR investigated individuals rated concordantly Aβ- all four methods. discordance examined relation APOE e4 genotype. Result Females had significantly higher WC reference; there no WM dynamic (Figure 1). Males regions difference greater compared 2). PVC decreased of but not WM. 87% classified Aβ+/- equal proportion males/females. More females Aβ+ only PVC, whereas more males without 3).