[18F]-MFBG Versus [123I]-MIBG and [18F]-PE2I in PD vs. MSA and DLB vs. AD

Study goal: The goal of this prospective head to head comparison is to evaluate the effectiveness of \[18F\]-MFBG PET in assessing cardiac innervation, comparing it with \[123I\]-MIBG SPECT The study's primary focus is on distinguishing between Parkinson's disease (PD) and multiple system atrophy (MSA), as well as between dementia with Lewy bodies (DLB) and Alzheimer's disease (AD). Main questions: * Feasibility: How well can \[18F\]-MFBG PET detect changes in myocardial uptake in PD and DLB compared to the expected normal values in healthy individuals and AD and MSA-P patients? How well can it differentiate between these groups based on the detected changes? * Non-inferiority: Is \[18F\]-MFBG PET as accurate as \[123I\]-MIBG SPECT in distinguishing between PD and MSA-P, and between DLB and AD? Participant requirements: For the main study, participants will be required to visit the hospital for 3 or 4 appointments. During these visits, they will undergo a screening visit, MRI brain scan, a comprehensive neurological assessment, \[18F\]-PE2I PET, \[123I\]-MIBG SPECT, and \[18F\]-MFBG PET scans. Additionally, a separate dosimetry study will be conducted, involving healthy subjects who will visit the hospital for a screening visit and undergo \[18F\]-MFBG PET scans.