HAI Book 2025 - Flipbook - Page 617
Singh-Reilly, Neha
145
Relationship between flortaucipir-PET and quantitative
susceptibility mapping in atypical Alzheimer9s disease
Neha Singh-Reilly1, Ryota Satoh2, Jonathan Graff-Radford1, Mary Machulda3, Val Lowe2, Keith
Josephs1, Jennifer Whitwell2
1
Department of Neurology, Mayo Clinic, Rochester, MN, US
Department of Radiology, Mayo Clinic, Rochester, MN, US
3
Department of Psychiatry & Psychology, Mayo Clinic, Rochester, MN, US
2
Background: Quantitative susceptibility mapping (QSM) can detect iron deposition or myelin loss in the brain by
estimating magnetic susceptibility properties. Iron is an important component in neurofibrillary tangles and is
known to co-localize in regions with tangle burden in Alzheimer9s disease (AD). Abnormal magnetic susceptibility
measured on QSM has been observed in atypical AD, although it is unclear if susceptibility is regionally related to
flortaucipir-PET uptake in atypical AD.
Methods: Forty atypical AD patients (visual variant=24, language variant=7, others=9) were recruited by the
Neurodegenerative Research group from the Department of Neurology, Mayo Clinic, Rochester, MN. They
underwent a 3T MRI scan with a five-echo gradient echo sequence for calculation of QSM (n=80), A´ (Pittsburgh
Compound-B) and a 18F-flortaucipir PET scan (n=73). All patients showed evidence of A´ positivity on PET. To
assess the relationship between QSM and flortaucipir-PET, two approaches were used i) Voxel-based regression
analysis using VoxelStats for the whole brain, and ii) region-of-interest (ROI)-based Spearman9s correlation
analyses using cortical and subcortical ROIs. All models were adjusted for age and sex as covariates and were
corrected for multiple comparisons, specifically the VoxelStats regression maps were corrected using random
field theory and the ROI-based correlation plots were corrected using false discovery rate.
Results: At the voxel-level, positive correlations between flortaucipir-PET and QSM were only observed in the left
caudate (Figure 1). At the ROI-level, no significant associations were found, although uncorrected data showed a
positive association in the occipital lobe (red circle) and a negative association between substantia nigra
susceptibility and occipital flortaucipir uptake (blue circle) (Figure 2). Since these findings did not survive
corrections, they should be interpreted cautiously.
Discussion: Our data provides little evidence that regional flortaucipir PET uptake is related to susceptibility
changes in patients with atypical AD.
HAI2025 - 617
