A Siemens ECAT EXACT HR + PET scanner was used to collect beta-amyloid using the C11-PIB tracer. Before injection, 10-min transmission scans for attenuation correction were collected. After injection of 8.5–15 mCi PIB, 60-min of dynamic data were acquired in 3D acquisition mode. Data were manually evaluated and corrected for motion. Then, a mean image was created by averaging across the first 8 min of data acquisition and used for co-registration. Each PET image was coregistered to that subjects T1 Freesurfer processed structural image and mapped into native PET space. The native space labels were then used to make ROI measurements computed using the Logan plot method with cerebellar grey matter as the reference region. The same atlas for extracting cortical thickness was used to extract mean DVR values from ROIs (i.e., the Desikan-Killiany atlas). Specifically, left and right precuneus ROIs were extracted as a proxy measure for beta-amyloid load. This region was chosen because it accumulates beta-amyloid early in AD (Jagust, 2009 (link)), shows reliable PIB binding (Mintun et al., 2006 (link); Rowe et al., 2007 (link)), has high inter-rater reliability (Rosario et al., 2011 (link)), and has been found to be highly correlated with ability discrepancy scores (McDonough et al. 2016 (link)). Descriptive statistics for the beta-amyloid can be found in Table 1.