Imaging in Neurodegeneration: Movement Disorders

Recent advances in the understanding of brain function are opening new frontiers in the investigation of movement disorders and neurodegeneration. The importance of the brain network-like characteristics is rapidly emerging together with increasing evidence that brain diseases imprint specific alterations on such networks. There is a strong need to determine molecular correlates associated with the network-type alterations to enable understanding of disease origin and mapping between clinical disease manifestations, genetic predispositions, and disease-triggering mechanisms. These considerations justify and highlight the importance of recent technological developments in positron emission tomography (PET) and integration of PET and magnetic resonance imaging (MRI), where the high neurochemical sensitivity of PET is complemented by MRI-derived measures of structural and functional connectivity. Ongoing developments of PET tracers suitable to image novel molecular targets and improvements in image reconstruction and analysis methods are further enhancing the relevance of imaging in addressing the complexity of brain function and disease-induced multidimensional alterations. This paper describes a conceptual justifications for the synergy between PET and MRI as related to neurodegeneration and movement disorders, discusses some predominantly PET-related developments relevant to and catalyzed by such synergy, and describes some novel multimodal metrics relevant to fundamental aspects of brain function altered early by disease.