Objective: We aimed to evaluate whether neuromelanin sensitive MRI (NM-MRI) features in the substantia nigra pars compacta(SNc) were of diagnostic value to differentiate untreated ET from de novo tremor-dominant PD (PDT).

Background: Essential tremor (ET) is the most common motor disorder in the elderly. However, it remains a challenge to differentiate ET from tremor-dominant Parkinson’s disease in the early stage, considering the complex clinical manifestations. T1-weighted neuromelanin sensitive imaging (NM-MRI) can reflect the survival of neuromelanin In substantia nigra.Previous NM-MRI studies have reported significant reductionsof SNc LC neuromelanin signals in patients with PD.The difference NM-MRI features between untreated ET and de novo tremor-dominant PD was rarely reported.

Methods: Eighteen untreated ET patients, 21 de novo PDT patients and 21 healthy control subjects were recruited. All the subjects underwent clinical examination, motor and cognitive evaluations, as well as NM-MRI. High signal intensity of lateral, central and medial SNc subregions on NM-MRI were evaluated using the width, signal intensity (contrast-to-noise ratio, CNR) and visual rating analysis. Diagnostic test performance of SNc values was investigated by using receiver operating characteristic (ROC) analyses and net reclassification improvement (NRI).

Results: .Intra-observer agreement were good to excellent for width and CNR of all SNc subregions The Kappa of visual rating analysis in SNc subregions between two raters were ranged from 0.364-0.736.The width and CNR values in lateral and central SNc subregions in PDT were significantly decreased compared with those in ET and control group. Using visual rating analysis, the total score of all SNc subregions were significantly reduced in PDT when compared with ET and control group. Width of lateral SNc subregion allowed the best differentiation between ET and PDT subjects (area under ROC curve, 0.923), and visual rating analysis also showed good diagnostic value (area under ROC curve, 0.865). NRI result showed that visual rating analysis and width of lateral SNc subregion had the same diagnostic power.

Conclusions: In conclusion, NM-MRI was proved to be a useful sequence in the diagnostic work-up of tremor disorders. Both width of SNc lateral subregion and visual analysis had good diagnostic power for the differentiating ET from PDT subtype, and the latter were more convenient. NM-MRI combining visual rating analysis of SNc was a potential diagnostic biomarker in clinical application.

« Back to 2018 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/neuromelanin-sensitive-mri-of-substantia-nigra-an-imaging-biomarker-to-differentiate-essential-tremor-from-tremor-dominant-parkinsons-disease/