PET Imaging in Parkinson's Disease

PET imaging first played an important role in the diagnosis of Parkinson's disease (PD) approximately 20 years ago when studies using the newly developed radiotracer, [18F]fluorodopa, demonstrated a clear dopamine loss in the basal ganglia. Other radiotracers were then developed to image presynaptic dopamine transporters, vesicular monoamine transporters and postsynaptic D2 receptor sites. These studies enhanced our understanding of the way in which the dopaminergic system is altered in PD. Shortly after [18F]fluorodeoxyglucose was used to quantify the expression of metabolic brain patterns in PD patients by comparing them with similar studies conducted in healthy volunteers. This dual approach of studying both dopamine and metabolism in the brain has now been applied successfully to diagnose and differentiate typical and atypical parkinsonian syndromes. These imaging biomarkers have since been applied to assess the effects of dopaminergic therapy and surgical techniques like pallidotomy, subthalamic stimulation, embryonic cell implantation, intraputaminal nerve growth factor infusion and viral vector gene therapy.