Magnetic resonance imaging changes in putamen nuclei iron content and distribution in normal subjects

To study patterns of iron deposition in the putamen in aging, we reviewed brain magnetic resonance imaging (MRI) scans of 56 normal subjects. We developed the Signal Hypointensity in the Putamen (SHIP) Scale, a semiquantitative measure, to evaluate putamen nuclei for extent of iron deposition relative to the globus pallidus. The SHIP score was highly reliable (kappa = 0.76) and significantly correlated with age (P < 0.0001). We found that age-related iron deposition in putamen nuclei follows a characteristic pattern along a posterolateral-to-anteromedial gradient. This gradient may be related to the microvasculature of the putamen. Other studies are needed to replicate our findings in patients with affective and other neuropsychiatric disorders and to clarify the pathophysiological mechanisms that govern these changes.