• Ability to comply with the study procedures and attend follow-up visits.

• Written informed consent from the participant or legal guardian.

• Male or Female between 45 years and 85 years of age (Females must meet additional criteria specified below, as applicable) a. Females must be of non-childbearing potential or using a highly effective method of birth control 14 days prior to until at least 24 hours after injection of \[18F\]PI-2620 or DaTscan.

⁃ i. Non-childbearing potential is defined as a female that must be either postmenopausal (no menses for at least 12 months prior to PET scan) or surgically sterile (bilateral tubal ligation, bilateral oophorectomy or hysterectomy).

⁃ ii. Highly effective method of birth control is defined as practicing at least one of the following: A birth control method that results in a less than 1% per year failure rate when used consistently and correctly, such as oral contraceptives for at least 3 months prior to injection, an intrauterine device (IUD) for at least 2 months prior to injection, or barrier methods, e.g., diaphragm or combination condom and spermicide. Periodic abstinence (e.g., calendar, ovulation, symptothermal, post-ovulation methods) is not acceptable.

⁃ b. Females of childbearing potential must not be pregnant, breastfeeding or lactating, or planning pregnancy during the duration of the study.

⁃ c. Non PPMI participant females of childbearing potential must have a negative serum pregnancy test at Screening and all females of childbearing potential must have negative urine pregnancy test prior to \[18F\]PI-2620 injection on day of Baseline PET scan.

⁃ d. Non PPMI participant females of childbearing potential must have a negative urine pregnancy test prior to Screening Visit DaTscan injection.

⁃ Healthy Controls:

⁃ a) Enrolled in the PPMI study as a healthy subject.

⁃ Disease specific inclusion criteria:

⁃ a) Parkinson's disease

⁃ a. Enrolled in the PPMI study as a sporadic PD or LRRK2 PD participant. b. Known CSF alpha synuclein seeding amplification assay status. c. Known Plasma phosphorylated Tau217 status. b) Progressive Supranuclear Palsy (PSP):

• Diagnosis of progressive supranuclear palsy (PSP) based on the Clinical diagnosis of progressive supranuclear palsy: The movement disorder society criteria (Höglinger et al., 2017).

• Symptom onset within 2-5 years prior to screening.

• Progressive motor symptoms including vertical supranuclear gaze palsy, postural instability, and other signs of parkinsonism.

• Evidence of striatal degeneration in form of abnormal DaTscan (previously obtained DaTscan since onset of motor symptoms may be used).

⁃ c) Corticobasal Syndrome (CBS):

• Diagnosis of corticobasal syndrome (CBS) based on clinical criteria, with asymmetric motor and cognitive dysfunction (Armstrong et al., 2013).

• Presence of limb apraxia, dystonia, alien limb phenomenon, and/or parkinsonism (e.g., rigidity, bradykinesia).

• Cognitive decline as indicated by impairment in attention, executive function, or memory.

• Evidence of striatal degeneration in form of abnormal DaTscan (previously obtained DaTscan since onset of motor symptoms may be used).