Analysis of 18F-XTR006 PET Imaging in Cognitively Normal Subjects, and Patients With MCI and AD

all patients will receive one injection of \[18F\]XTR006, a PET radiopharmaceutical selective for NFTs. For the injection, subjects will receive a target dose of 4-6 mCi IV as a bolus injection. \[18F\]XTR006 injection will be followed by a 10 ml saline flush.