- Prior participation in the study titled Dopamine Transporter Imaging Assessment of Parkinson's Disease Progression (DAMD17-99-1-9472) [123I] B-CIT and Spect in Vivo Imaging Assessment of Dopamine Transporter Density in Subjects With Early Parkinson's Disease Participating in Earlier Vs. Later Levodopa in Parkinson's Disease (ELLDOPA)].