Evaluation of Imaging Characteristics of [18F]PI-2620 PET in AD and PSP Patients Using High and Low Specific Activity

\[18F\]PI-2620 is a radioactive diagnostic agent being developed for the indication of PET imaging of the brain to detect tau pathology in adult patients who are being evaluated for neurodegenerative decline. All patients will receive two administrations of \[18F\]PI-2620 at a radioactive dose of 185 MBq, one with high specific activity (≤ 5 µg tracer mass dose), another one with low specific activity (40-50 µg tracer mass dose).