Developments in neuroimaging: positron emission tomography.

Positron emission tomography (PET) is a powerful technique to quantitatively assess brain function in vivo. In Parkinson's disease (PD), PET can assist in the identification of dopamine deficiency, the characterization of dopamine and other neurotransmitter receptors and transporters, serve as a biomarker and provide insights into motor and non-motor complications of PD. PET can also shed light on mechanisms that underlie disease, such as aberrant protein deposition and neuroinflammation. Emerging developments in multimodal imaging offer the opportunity to study multiple questions concurrently and offer great promise for the future.