Xiangchuan Chen1,
Daniel Huddleston2, 3, Jason Langley1,
Xiaoping P. Hu1
1Biomedical
Imaging Technology Center, Emory University, Atlanta, GA, United States; 2Kaiser
Permanente Center for Health Research Southeast, Atlanta, GA, United States; 3Department
of Neurology, Emory University, Atlanta, GA, United States
Alterations in the substantia nigra (SN) in Parkinsons disease (PD) were investigated with magnetic resonance imaging (MRI). By using a semi-automated approach, contrast-to-noise ratio and number of voxels of the SN were measured, which showed significant differences between a PD and a control group. These results suggest that loss of neuromelanin containing neurons, as occurs in PD, can be measured with this MRI approach. Moreover, these two MRI measures were significantly correlated with the orthostatic blood pressure drop, a phenotypic measure relevant to PD, implicating the role of SN in the pathophysiology of orthostatic hypotension in PD.