The underlying goal of this open label imaging study is to optimize the imaging outcome for ALTROPANE® in mild to moderate PD subjects. All study procedures will be conducted at the Institute for Neurodegenerative Disorders (IND) and Molecular NeuroImaging (MNI) in New Haven, CT. Subjects with PD (n=15) will be recruited to undergo ALTROPANE® SPECT. All subjects will undergo written informed consent and a screening evaluation including baseline clinical laboratory testing, a physical and neurological evaluation. Subjects will be asked to undergo an injection of ALTROPANE® followed by up to 60 minutes of serial dynamic imaging. Subjects will be asked to undergo a second imaging visit two-six weeks following the initial imaging visit to assess the reproducibility of the imaging outcome. The imaging analyses will be performed by an image-processing specialist who will remain masked to clinical severity. The primary imaging outcome measure will be the brain regional distribution volumes expressed as a target region to occipital ratio. Striatal regions of interests for caudate and putamen will be defined and placement standardized based on previously optimized region placement protocols. Imaging data will also be analyzed using an automated objective striatal analysis software package.