HAI Book 2025 - Flipbook - Page 218
Amaral, Livia
47
Comparison of topographical patterns of abnormalities of the tau PET
tracers [18F]Flortaucipir, [18F]MK6240, [18F]PI2620, and [18F]RO948
Livia Amaral1, Guilherme Povala1, Guilherme Bauer-Negrini1, Emma Ruppert1, Bruna Bellaver1,
Firoza Lussier1, Pamela L. Ferreira1, Joseph Masdeu2, Dana L. Tudorascu1, David SoleimaniMeigooni3, Juan Fortea4, Val Lowe5, Hwamee Oh6, Belen Pascual2, Brian A. Gordon7, Pedro
Rosa-Neto8, Suzanne Baker9, Tharick A. Pascoal1
1
University of Pittsburgh, Department of Psychiatry, Pittsburgh, PA, US
Houston Methodist Research Institute, Department of Neurology, Houston, TX, US
3
University of California San Francisco, Memory and Aging Center, San Francisco, CA, US
4
Hospital de la Santa Creu i Sant Pau, Sant Pau Memory Unit, Department of Neurology, Barcelona, ES
5
Mayo Clinic, Department of Radiology, Rochester, MN, US
6
Brown University, Department of Psychiatry and Human Behavior, Providence, RI, US
7
Washington University in St. Louis, Department of Radiology, St. Louis, MO, US
8
Translational Neuroimaging Laboratory, McGill University Research Centre for Studies in Aging, Douglas Research
Institute, Montréal, QC, CA
9
Lawrence Berkeley National Laboratory, Berkeley, CA, US
2
Objective: Multiple tau PET tracers have been shown to accurately capture tau tangle deposition in the human
brain. However, single-tracer studies have demonstrated different uptake patterns across the AD spectrum. This
study uses head-to-head acquired tau PET tracers (the HEAD study) to compare the topographical spread of tau
pathology across the four most widely used tau PET tracers.
Methods: We studied 66 individuals (30 CU (10% A+) and 36 CI (33% A+)) with [18F]Flortaucipir, [18F]MK6240,
[18F]PI2620, and [18F]RO948 tau PET tracers. PET SUVR was calculated using the inferior cerebellar grey matter as
the reference region at 8mm FWHM. PET topographical spread was assessed using the percentage of abnormal
voxels (PAV) above the mean + 2.5 SD of CU amyloid-negative individuals. ROC AUCs were used to compare the
performance of SUVR and PAV in the meta-temporal ROI for identifying the presence of cognitive impairment (CU
versus CI).
Results: PAV demonstrated a slightly higher AUC than SUVR in identifying cognitive impairment across all four tau
PET tracers (Figure 1). PAV progressively increased from CU to MCI and dementia, partially following Braak stage
patterns across the four tracers (Figure 2). Probabilistic 3D maps indicated that MCI subjects exhibited the
highest concentrations of tau abnormality (20-40%), mostly confined to the entorhinal cortex and laterally (Figure
3). Individuals with dementia showed a higher concentration of tau PET abnormalities in the parietal and temporal
lobes, with very similar patterns across tracers.
Conclusion: In this preliminary analysis, we found that tau PET topographical spread (measured with PAV) was
associated with cognitive impairment. [18F]MK6240 exhibited the most consistent regional abnormality patterns
in individuals in early disease stages within Braak I-II regions. All four PET tracers showed substantial tau
abnormality regional spread in individuals with dementia, with the highest concentrations in the temporoparietal
regions.
HAI2025 - 218
