E09 Magnetic resonance imaging visual analysis of neuromelanin and nigrosome-1 for the assessment of striatonigral disfunction in huntington’s disease

Background Nigrostriatal dopaminergic neuron degeneration with loss of Substantia Nigra (SN) and Locus Coeruleus (LC) neurons, as well as disruption of iron homeostasis, have been reported in Huntington’s Disease (HD), but literature is still scarce. Recently developed magnetic resonance imaging (MRI) biomarkers, such as neuromelanin-sensitive MRI (NM-MRI) and Nigrosome-1 (N1) visualization on susceptibility-weighted imaging (SWI), permit in vivo evaluation of changes in NM containing neurons of the SN and LC and in iron deposition. Aim The aim of this study was to use these novel MRI methods to further clarify SN and LC involvement in HD, through visual analysis. Methods Cross-sectional comparative study analyzing NM and N1 in HD patients and healthy controls (HC). Visual analysis of the SN and LC NM and of the N1 was performed. Fisher’s exact test was used to compare visual analysis ratings between groups. Additionally, SN NM area was obtained using semi-automatic segmentation and median area was used for non-parametric analysis. Results Twelve HD patients and 13 HC were included. LC and SN NM signal intensity were found to be consistently reduced in HD. Visual and semi-quantitative analysis of the SN-NM area did not show significant differences between the groups. No significant differences were found in the analysis of the N1. Conclusions Reduction of LC and SN NM signal on NM-MRI corroborates previous neuropathological findings suggesting striatonigral dysfunction in symptomatic HD patients. Our results suggest that visual analysis may be useful for the evaluation of NM-MRI and N1 in HD patients in clinical settings.