PET Imaging Evaluation of [11C]SY08

Inclusion Criteria:

• General Inclusion criteria, all subjects must:

1. Age 50-80
2. Be able to provide written informed consent or assent
3. Be able to read, speak and understand English (The investigators do not have theresources necessary to properly study non-English speaking patients in thisstudy, given that translation and validation of the assessment tools would benecessary)
4. Be willing and able to participate in one PET/MRI scanning session Additional Inclusion criteria for PD patients, subjects must:
5. Have an existing diagnosis of idiopathic PD, using consensus criteria
6. Stable medications for at least 30 days
7. Hoehn and Yahr stage I-IV
8. A study partner who can answer questions pertaining to daily functioning Additional Inclusion criteria for MSA patients, subjects must:
9. Have an existing diagnosis of MSA, using consensus criteria
10. Stable medications for at least 30 days
11. MSAp or MSAc
12. A study partner who can answer questions pertaining to daily functioning Additional Inclusion criteria for DLB patients, subjects must:
13. Have an existing diagnosis of probable DLB, using consensus criteria
14. Stable medications for at least 30 days
15. Clinical Dementia Rating Scale (CDR) < 0.5
16. A study partner who can answer questions pertaining to daily functioning

Exclusion Criteria:

• General Exclusion Criteria (All Subjects)

1. History of vascular risk factors (e.g. hypertension, hyperlipidemia), if notwell-controlled
2. Major psychiatric disease (e.g.schizophrenia)
3. History of stroke
4. Focal brain lesions on MRI scans
5. History of other major illnesses including, but not limited to, major kidney orliver problems or significant neurological illness
6. Recent surgery that is deemed major by our reviewing physician or nursepractitioner within the past 6 months
7. History of head trauma (as defined as having any insults to the brain that mayhave resulted from an external mechanical force, such as rapid acceleration ordeceleration, impact, blast waves, or penetration by a projectile)
8. Impaired elimination (as defined as having problems with urination) unless beingmanaged
9. Past or present diagnosis of bipolar disorder or other Axis I diagnosis, (treateddepression is allowed)
10. Any present substance abuse including drug/alcohol abuse
11. Inability to lie flat on camera bed for up to 90 min
12. Pregnancy or breastfeeding
13. Metallic foreign bodies that would be affected by the MRI magnet, or fear ofenclosed spaces likely to make the subject unable to undergo an MRI scan
14. Recent exposure to radiation (i.e., PET from other research) that, when combinedwith this study, would be above the allowable limits (50 milliSieverts) General MR and PET safety exclusion criteria listed below
15. Ferromagnetic implants such as aneurysm clips, surgical clips, prostheses, artificialhearts, valves with steel parts, metal fragments, shrapnel, metallic tattoos anywhereon the body, tattoos near the eye, steel implants, ferromagnetic objects such asjewelry or metal clips in clothing
16. Electrical implants such as cardiac pacemakers or perfusion pumps
17. Pre-existing medical conditions including a likelihood of developing seizures orclaustrophobic reactions, and any greater than normal potential for cardiac arrest
18. Is unable to lie comfortably on a bed inside a PET camera with their head in the fieldof view for 60 to 90 minutes as assessed by physical examination and medical history (e.g. back pain, arthritis)
19. Pregnancy: A negative serum pregnancy test is required on the day of the PET procedurein women of child bearing potential
20. Body weight of > 300 lbs (weight limit of the MRI table)
21. Breast feeding mothers Exclusion Criteria for Subjects Undergoing Blood Draws Through an Arterial Line During PETScan
22. An abnormal result on the modified Allen's test on both hands
23. Raynaud syndrome
24. Bleeding disorder
25. Use of anticoagulants such as Coumadin, Plavix or Lovenox
26. An allergy to Lidocaine