Associations between iron and mean kurtosis in iron-rich grey matter nuclei in aging

Mean kurtosis in iron-rich grey matter has values similar to that seen in white matter. We suspect these elevated values may be related to iron. Multi-shell diffusion and multi-echo gradient echo acquisitions were used to derive mean kurtosis and R₂*, respectively. Mean kurtosis and R₂* were measured in subcortical grey matter nuclei and white matter tracts in 93 older adults and 62 younger adults. Grey matter regions exhibited higher mean kurtosis and R₂* in the older adult group whereas white matter regions had reduced mean kurtosis in the older adult group. Grey matter mean kurtosis was significantly correlated with R₂* iron-rich grey matter nuclei in both groups. Our findings indicate that higher mean kurtosis in iron-rich grey matter structures may be due to either increased tissue complexity or to decreases in signal-to-noise ratios from iron deposition.