We hypothesized that hybrid PET/MRI with the second-generation tau PET tracer [18F]PI-2620 provides phenotype-specific information in a one stop-shop manner about tau accumulation, brain atrophy, brain perfusion, functional network alterations and white matter microstructural alterations which can be used to differentiate between aAD and PCA and lvPPA. This evidence concerns the gene MAPT and Brain atrophy.