Study of Biodistribution, Metabolism, Excretion and Brain Uptake of 11C-HY-2-15

Inclusion Criteria: * The entire cohort will include men and women clinically diagnosed with MSA, PD, PSP or are healthy controls. A sub-set of these participants who undergo whole body scanning that will be used for analysis of biodistribution and dosimetry calculations. * Patients in all cohorts will be male or female adults from 40 to 80 years of age. * Participants must be informed of the investigational nature of this study and be willing to provide written informed consent and participate in this study in accordance with institutional and federal guidelines prior to study-specific procedures or Participants who are deemed unable to provide informed consent must have a designated study partner present for consent and to accompany them to study visits * We will ask PD/MSA/PSP participants to agree to brain donation but this choice is not mandatory for participation in this study. * Diagnosis-specific inclusion criteria: Clinical diagnoses will be determined by consensus committee for diagnostic agreement (PD, MSA, PSP or Healthy Control) Exclusion Criteria: * Females who are pregnant or breast feeding will be excluded, a urine pregnancy test will be performed in women of child-bearing potential prior to injection of 11C HY-2-15, 11C-PiB or Florbetaben * Forms of parkinsonism other than PD, PSP and MSA as defined above * Major psychiatric disorder (e.g. schizophrenia or bipolar disorder) - major depressive disorder is allowed * History of significant or ongoing alcohol abuse or substance abuse or dependence based on medical record review or self-reported * Contraindications or inability to tolerate imaging, arterial line or IV placement or blood draw procedures in the opinion of an investigator or treating physician * Contraindication to MRI, such as non-compatible implanted medical device * PSP and MSA subjects will be excluded if they have a history of any prior positive ß-amyloid PET scan or positive CSF AD biomarkers. * Any current medical condition, illness, or disorder as assessed by medical record review and/or self-reported that is considered by a physician or investigator to be a condition that could compromise participant safety or successful participation in the study