One-year Follow-up of Iron in Basal Ganglia - R2*: a Biomarker of Parkinson's Disease Progression?

The study of non-invasive and reliable biomarkers to track progression of Parkinson's disease (PD) is essential while disease-modifying treatments are being developed. Many clinical biological or imaging biomarkers have been tested but no "gold standard" has been found as of yet. Among these, Magnetic Resonance Imaging (MRI) relaxometry using R2\* measurement (R2\* = 1/T2\*), which is a validated marker for estimating brain iron concentration, appears to be an attractive technique because its safety, rapidly measured in clinical conditions and its ease to ensure individual longitudinal follow-up. Current data of cross sectional studies of R2\*, which have shown an iron increase in Substantia Nigra (SN), led to suppose that it could be a biomarker of disease vulnerability. Recently, the investigators have conducted the first longitudinal follow-up of R2\* (1.5 T MRI), which showed a rapid R2\* increase in both parts of the SN and in the caudal putamen. We propose, here, a multicenter prospective study of one-year cohort follow-up of R2\* variations (ΔR2\*) in three regions of interest (ROIs) (the SN, the Ventral Tegmental Area (VTA) and the Putamen) of 160 patients with PD, using a 3 Tesla MRI, to evaluate the potential interest of R2\* as a biomarker of disease progression. The variation of R2\* (ΔR2\*) will be correlated with clinical markers of disease progress, non-motor symptoms. 80 healthy controls subjects will also be included to assess the effect of aging on cerebral physiological iron levels.