Challenges in molecular imaging of Parkinson's disease: a brief overview

Positron emission tomography (PET) is a sensitive and specific non-invasive molecular imaging technique providing quantitative images and data on biochemical pathways, molecular interactions, drug pharmacokinetics and pharmacodynamics. The PET measurement of regional biochemical functions requires a rational design of the radiolabelled probes employed. When choosing a drug to radiolabel there are many considerations, the most important being the potential of the drug to provide the information that is required in vivo. For example, when developing a radiolabelled probe for measuring the regional concentration of a neurotransmitter receptor the affinity and selectivity of the drug need to be considered. Other factors which influence a decision about which drug to radiolabel include the ability of the drug to reach its target, drug lipophilicity and metabolism, toxicity and the amenability to radiolabelling. PET has been applied in studies of Parkinson's disease (PD) and has provided important information on disease on-set and progression. This brief overview aims to outline the challenges and capabilities of PET and the more commonly used molecular probes in PD studies.