CenTauR: Towards a Universal Scale and Masks for Standardizing Tau Imaging Studies

Abstract

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.

Label-free and reference region-free X-ray cross-β index for quantifying protein aggregates of neurodegenerative diseases

“…Particularly for AD, the currently available quantitative metrics for the PET imaging include standardized uptake value ratio (SUVr), z-score, centiloid and the recently reported A load, A index, AMYQ and CenTauR [6,9]. The SUVr, ratio of radiotracer uptake between target and reference region is widely validated against histopathology on a variety of clinical populations.…”

“…The latest study reports highlighted the requirement of establishing the discriminatory power of these metrics to differentiate patient populations based on disease severity, importantly the distinction between MCI and controls and MCI and AD. On the tau tracer side, CenTauR has been reported for the standardization of quantitative tau PET imaging measures across different tau tracers [9]. However, tau PET tracers are still limited to the clinical experimental studies with only one [18F] Flortaucipir tracer approved by FDA for the imaging of neurofibrillary tangles in cognitively impaired AD patients [17].…”

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“…The four 5-minute flortaucipir PET scans were corrected for motion, averaged, smoothed to a uniform resolution of 6 mm, and co-registered to the individual participant's accompanying T1weighted MRI scan. Using the CenTauR standardized masks [29], SUVRs were estimated for regions of interest (ROIs) as defined by FreeSurfer v7.1. The mesial temporal meta-ROI included regions with early tau PET signal (entorhinal, parahippocampus and amygdala), and the temporal-parietal meta-ROI included regions with both early and later tau PET signal (the entorhinal, parahippocampus, amygdala, fusiform, inferior and middle temporal gyri).…”