Objective: To assess the sensitivity of multi-echo GRE and DTI MR imaging to changes in Substantia Nigra (SN) in early Parkinson’s disease (PD)

Background: In PD, there is a dopaminergic cell loss in the SN with the accumulation of iron even before the onset of PD motor symptoms. Different promising quantitative MR techniques have been used to evaluate changes in the SN, namely DTI and multi-echo GRE, as a diagnostic marker for PD. It is unknown how sensitive these MR markers in very early stages of clinical PD.

Methods: A 1-year prospective study of idiopathic PD patients (<2 years of parkinsonian symptoms) and age- and sex-matched healthy controls (HC). Clinical (MDS-UPDRS part III, PD medications) and MRI data were collected every 6 months. MRI data (3T MRI) was collected using the following modalities: 3D multi-echo GRE sequence (R2* and quantitative susceptibility imaging/QSM maps), diffusion tensor EPI (fractional anisotropy (FA), mean diffusivity (MD)) and structural MPRAGE. Co-registration was performed using FSL. We used both manual ROIs and automated post-processing for the SN. For the latter, a subcortical probability atlas in MNI152 space was generated. Data analyses were blinded to group and visit. At each data point, we compared between-group mean differences (two-tailed t-test). A p<0.1 was deemed significant.

Results: We included 10 PD patients (mean age: 61.5 ± 9.4 years; 7 males) and 10 HC (mean age: 62.3 ± 10.3 years, 7 males). The mean duration of parkinsonian symptoms was 1.6 ± 0.8 years. In the manual ROI approach, QSM values (ppm) were higher in the PD group in the nigrosome-1 region only at 6 months (0.06±0.02 vs. 0.03±0.01, p=0.004) and 12 months (0.03 ±0.02 vs. 0.06±0.03, p=0.016). In the automated analysis, there were higher values in the PD group for R2* (1/s) and QSM (ppm) in the SN (p<0.1) only at 12 months (R2*: 39.6 ±6.9 vs. 35.7±4.6; QSM: 0.07 ±0.03 vs. 0.04 ±0.03). There were no consistent changes in​ DTI measures.

Conclusions: Our data suggest iron-sensitive imaging and DTI MRI may not differentiate PD from healthy controls in very early stages of the clinical disease. R2* and QSM imaging were more sensitive to change in SN compared with DTI. Data co-registration and a subcortical atlas-based analysis process allow evaluating a large amount of multi-parametric brain MRI data in a user-independent way. A larger study is warranted.

« Back to 2018 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/multi-echo-gre-and-dti-mr-imaging-of-the-substantia-nigra-in-early-parkinsons-disease-a-pilot-1-year-prospective-controlled-study/