Amyloid PET Tracers and Imaging in Alzheimer's Disease

In the PARIS discovery cohort, 3 amyloid PET tracers were used: (¹⁸F)florbetapir (Amyvid; Lilly Diagnostics), (¹⁸F)florbetaben (Neuraceq; Life Molecular Imaging) or (¹⁸F)flutemetamol (Vizamyl; GE Healthcare). While in the IDEAS study, amyloid PET scans were interpreted visually by local radiologists and nuclear medicine physicians, for PARIS, amyloid PET images were obtained and processed by the American College of Radiology and analyzed by 2 board-certified radiologists with amyloid PET tracer–specific training. In the MissionAD data set used for this study, 2 amyloid PET tracers were used: (¹⁸F)florbetapir and (¹⁸F)florbetaben, and amyloid PET images were processed by Bioclinica. Image analyses, including standardized uptake value ratio to Centiloid conversion, are described in the eMethods in the Supplement. For purposes of determining eligibility for MissionAD, PET visual read was used. Based on published evidence,^{21 (link),22 (link)} we a priori defined amyloid positivity for our analyses as Centiloid value greater than 25, which is a more sensitive threshold for brain amyloid plaques than visual read.