New MRI Biomarkers Advance the Characterization of Parkinson Disease.

The pathophysiology of idiopathic Parkinson disease (PD) is traditionally characterized as substantia nigra degeneration, but careful examination of the widespread neuropathological changes suggests individual differences in neuronal vulnerability. A major limitation to studies of disease progression in PD has been that conventional MRI techniques provide relatively poor contrast for the structures that are affected by the disease, and thus are not typically used in experimental or clinical studies. Here, we review the current state of structural MRI as applied to the analysis of the PD brain. We also describe a new multispectral MRI method that provides improved contrast for the substantia nigra and basal forebrain, which we recently used to show that these structures display different trajectories of volume loss early in the disease.