Objective: To investigate substantia nigra (SN) MRI abnormalities through Neuromelanin (NM) and diffusion MRI (dMRI) with Neurite Orientation Dispersion and Density Index (NODDI) in the premotor and motor stages of parkinsonism.

Background: Substantia nigra degeneration is the hallmark of Parkinson’s Disease (PD), it is present since its premotor stage and also in atypical parkinsonism such as Multiple System Atrophy (MSA). Non-invasive, in-vivo SN biomarkers are critical for both clinical and research approaches.

Method: Anterior and posterior SN (aSN, pSN) NM volume and NODDI abnormalities were investigated in 19 Parkinson’s Disease (PD), 14 REM sleep behaviour disorders (RBD), 11 MSA patients and 18 healthy controls (HC). A summary of MRI processing is show in Figure 1.

Results: Between-group differences (Kruskal-Wallis test, p<0.05) were found in aSN and pSN NM, and in pSN free water fraction (FWF), with MSA and PD showing lower NM and higher FWF compared to HC (Figure 2). In the combined disease groups, NM volume in aSN showed inverse associations (Pearson’s r, p<0.05) with neurite density index (NDI) and FWF, while in pSN NDI was inversely associated with NM (Figure 3). In the PD-RBD subgroup, MDS-UPDRS-III was associated with aSN NM (r=-0.391, p=0.027; pSN r=-0.331, p=0.065) and with pSN FWF (r=0.499, p=0.003; aSN r=0.321, p=0.068); a non-significant trend was shown with pSN NDI (r=0.339, p=0.054).

Conclusion: SN abnormalities from different scanning and processing techniques were associated and related to motor impairment. This may indicate the potential to capture different yet related aspects of SN degeneration over the course of parkinsonism. Therefore, NM-MRI and dMRI-NODDI of the SN may yield meaningful disease biomarkers for research and clinical applications.

« Back to 2022 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/multimodal-mri-assessment-of-the-substantia-nigra-in-premotor-and-motor-stages-of-parkinsonism/