PIB PET Imaging in Down Syndrome

Details of the PIB PET data acquisition and processing have been published previously (Annus et al., 2016 (link)). Briefly, PIB PET images were acquired in 3D mode on a GE Advance scanner (General Electric Medical Systems, Milwaukee, WI, USA) for 90 minutes post-PIB injection in 58 frames. Only participants with DS were assessed for amyloid. Cortical regional PIB analysis was based on Brodmann areas, whereas subcortical regions of interest were based on deep gray matter parcelations using FIRST (Patenaude et al., 2011 (link)) and included the striatum (caudate nucleus and putamen), amygdala, thalamus, and hippocampus. For each region of interest, nondisplaceable binding potential was obtained using a basis function implementation of the simplified reference tissue model (Gunn et al., 1997 (link)) with superior cerebellar gray matter as reference region. PIB-positive and PIB-negative groups were assigned on the basis of striatal nondisplaceable binding potential, which had previously revealed a bimodal distribution with clear separation of positive and negative groups (Annus et al., 2016 (link)). Of the 46 participants with DS, 19 were PIB-positive.