HAI Book 2025 - Flipbook - Page 672
Povala, Guilherme
163
Defining the grey zone thresholds for tau PET positivity using the
Uni�㔏 scale
Guilherme Povala1, Bruna Bellaver1, Guilherme Bauer-Negrini1, Emma Ruppert1, Marina
Medeiros1, Livia Amaral1, Firoza Lussier1, Pamela Lukasewicz1, Carolina Soares1, Dana
Tudorascu1, Joseph Masdeu2, Belen Pascual2, Brian Gordon3, Val Lowe4, Hwamee Oh5, David
Soleimani-Meigooni6, Pedro Rosa-Neto7, Suzanne Baker8, Tharick A. Pascoal1
1
University of Pittsburgh, Department of Psychiatry, Pittsburgh, PA, US
Houston Methodist Research Institute, Neurology, Houston, TX, US
3
Washington University in St. Louis, Department of Radiology, St. Louis, MO, US
4
Mayo Clinic, Radiology, Rochester, MN, US
5
Brown University, Psychiatry, Providence, RI, US
6
University of California San Francisco, Memory and Aging Center, San Francisco, CA, US
7
Translational Neuroimaging Laboratory, McGill University Research Centre for Studies in Aging, Douglas Research
Institute, Montréal, QC, CA
8
Lawrence Berkeley National Laboratory, Berkeley, CA, US
2
Introduction: Tau PET measures are continuous, and dichotomized thresholds are subject to conceptual and
analytical idiosyncrasies. Understanding the limitations in the transition from tau-negative to positive
classifications is crucial for the effective use of these thresholds. This study aims to determine the confidence
levels of tau PET thresholds of abnormality by characterizing their "gray zone" using the universal tau PET scale
(Uni�㔏, www.unitau.app).
Methods: We evaluated 402 individuals across aging and AD spectrum from HEAD study, with head-to-head scans
for MK6240 and Flortaucipir. Uni�㔏 estimates were derived from the Centaur Meta-Temporal ROI. Tau positivity (T+)
was defined as Uni�㔏 values above the mean + 2.5 SD of young individuals (
