F 18 T807 Tau PET Imaging of Frontotemporal Dementia (FTD)

Inclusion Criteria: 1. Male or female participants, at least 18 years of age. 2. Clinically diagnosed with frontotemporal dementia (FTD), or a carrier of a mutation known to cause FTD (with or without symptoms); or a normal control. 3. Participant is able and willing to undergo testing (MRI or CT, PET, radioactive tracer injection, LP; for those unable to undergo an MRI, CT will be used to generate regions-of-interest). 4. Pre-menopausal women will have a negative a urine pregnancy test within 24 hours of T807 drug administration. Exclusion Criteria: 1. Has any condition that, in the Investigator's opinion, could increase risk to the participant, limit the participant's ability to tolerate the experimental procedures, or interfere with the collection/analysis of the data (for example, participants with severe chronic back pain might not be able to lie still during the scanning procedures). 2. Is deemed likely unable to perform the imaging procedures for any reason. 3. Has a history of Torsades de Pointes or is taking medications known to prolong QT interval. To determine who will be excluded from this study based on this criterion, we will review participant's medical history and current medications at time of screening. Participants will be excluded from the study if any of the following restricted medications are being taken: * Disopyramide * Dofetilide * Ibutilide * Procainamide * Quinidine * Sotalol * Bepridil 4. Has hypersensitivity to F 18 T807 or any of its excipients. 5. Contraindications to PET, PET-CT or MR (e.g. electronic medical devices, inability to lie still for long periods) that make it unsafe for the individual to participate. 6. Severe claustrophobia. 7. Currently pregnant or breast-feeding. 8. For those electing to undergo the optional lumbar puncture: on anticoagulant of any form prior to lumbar puncture.