MAPT and Alzheimer disease: Overall findings with [18F]RO948 supported in vitro findings of high specificity of [18F]RO948 for AD-type neurofibrillary tangles.18,20 Within the I-II (entorhinal cortex) ROI, primary age-related tauopathy43 may account for the participants (1 with no cognitive impairment and 1 with vascular dementia) who showed tau PET positivity using [18F]RO948 (hypothetically, since primary age-related tauopathy cannot be diagnosed during life).