Imaging in Parkinson's Disease.

Parkinson's disease (PD) is a chronic neurodegenerative disease characterized by the loss of nigrostriatal dopaminergic neurons and aggregation of misfolded α-synuclein in Lewy bodies. The underlying mechanisms of neurodegeneration in PD are still unknown, and there are no disease-modifying treatments to slow the neurodegenerative processes. There is an urgent need to identify biomarkers that are able to monitor disease progression and assess the development and efficacy of novel disease-modifying drugs. Over the past years, neuroimaging techniques such as magnetic resonance imaging (MRI), single-photon emission computed tomography (SPECT), and positron emission tomography (PET) have provided important advances in our understanding of PD. MRI provides information about structural and functional organization of the brain, while SPECT and PET can detect molecular changes in the brain. Here, we review the current neuroimaging literature in sporadic and genetic PD, which have contributed to our understanding of the physiopathological mechanisms of the disease.