Evaluation of brain iron content in idiopathic REM sleep behavior disorder using quantitative magnetic resonance imaging.

Background: Neuroimaging studies in patients with idiopathic rapid eye movement sleep behavior disorder (iRBD) show similar structural and functional changes to alpha-synucleinopathies, including PD. Until now, there have been few attempts to characterize brain iron deposition in iRBD. The aim of this study was to investigate brain iron content in patients with iRBD using quantitative magnetic resonance imaging (MRI).

Methods: 3-T MRI was performed in 15 patients with iRBD and 20 age-matched healthy control subjects. In order to evaluate the iron-related neurodegenerative changes, we assessed volume and transverse relaxation rate (R2*) simultaneously. We used both region-based and voxel-based analysis.

Results: No significant differences in R2* values were found between iRBD groups and healthy control subjects. There were no areas of significantly reduced or increased gray matter and white matter volume in the iRBD group. Instead, lateral ventricle volumes measured automatically by FreeSurfer were significantly larger in patients with iRBD than in healthy controls (P < 0.05).

Conclusion: The present study suggests that iron-related R2* values may not be an imaging biomarker for neurodegeneration in iRBD.