Abstract
BACKGROUND: Previous studies investigating nigral iron accumulation used T(2) or T(2) *-weighted contrasts to define the regions of interest (ROIs) in the substantia nigra with mixed results. Because these contrasts are not sensitive to neuromelanin, ROIs may have inadvertently missed the SNpc. An approach sensitive to neuromelanin should yield consistent results. We examine iron deposition in ROIs derived from neuromelanin-sensitive and T(2) *-weighted contrasts, respectively. METHODS: T(1) -weighted and multiecho gradient echo imaging data were obtained in 2 cohorts. Multiecho gradient echo imaging data were analyzed using neuromelanin-sensitive SNpc ROIs as well as T(2) *-weighted SNr ROIs. RESULTS: When compared with controls, significantly larger R(2) * values were seen in the SNpc of PD patients in both cohorts. Mean R(2) * values in the SNr of PD patients showed no consistency, with 1 cohort showing a small, statistically significant increase, whereas the other cohort exhibited no statistical difference. CONCLUSION: Mean R(2) * in the SNpc defined by neuromelanin-sensitive MRI is significantly increased in PD. © 2018 International Parkinson and Movement Disorder Society.