INTRODUCTION: Recently, an increasing number of tau tracers have become available. There is a need to standardize quantitative tau measures across tracers, supporting a universal scale. We developed several cortical tau masks and applied them to generate a tau imaging universal scale. METHOD: 1045 participants underwent tau scans with either 18F-Flortaucipir, 18F-MK6240, 18F-PI2620, 18F-PM-PBB3, 18F-GTP1 or 18F-RO948. The mask was generated from cognitively unimpaired Aβ- subjects and AD patients with Aβ+. Four additional regional cortical masks were defined within the constraints of the global mask. A universal scale, the CenTauRz, was constructed. RESULTS: None of the regions known to display off-target signal were included in the masks. The CenTauRz allows robustly discrimination between low and high levels of tau deposits. DISCUSSION: We constructed several tau-specific cortical masks for the AD continuum and a universal standard scale designed to capture the location and degree of abnormality that can be applied across tracers and across centres.

Victor Villemagne has received research grants from NHMRC (GNT2001320), the Aging Mind Foundation (DAF2255207) and NIH 2P01AG025204-16) and is and has been a consultant or paid speaker at sponsored conference sessions for Eli Lilly, Life Molecular Imaging, ACE Barcelona, and IXICO. Sandra Sanabria Bohorquez and Robby Weimer are a full-time employee and stock owner of Roche. Santiago Bullich and Andrew Stephen are full-time employee of Life Molecular Imaging GmbH. Hitoshi Shimada and Makoto Higuchi hold patents on compounds related to the present report (JP 5422782/EP 12 884 742.3/CA2894994/HK1208672). Christopher C. Rowe has received research grants from NHMRC, Enigma Australia, Biogen, Eisai and Abbvie. He is on the scientific advisory board for Cerveau Technologies and consulted for Prothena, Eisai, Roche and Biogen Australia. Oskar Hansson has acquired research support (for the institution) from ADx, AVID Radiopharmaceuticals, Biogen, Eli Lilly, Eisai, Fujirebio, GE Healthcare, Pfizer, and Roche. In the past 2 years, he has received consultancy/speaker fees from AC Immune, Amylyx, Alzpath, BioArctic, Biogen, Cerveau, Eisai, Eli Lilly, Fujirebio, Genentech, Merck, Novartis, Novo Nordisk, Roche, Sanofi and Siemens. The other authors did not report any conflict of interest.

The research was supported by the Australian Federal Government through NHMRC grants APP1132604, APP1140853 and APP1152623 and by a grant from Enigma Australia.

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