Brain iron deposition in type 2 diabetes mellitus with and without mild cognitive impairment—an in vivo susceptibility mapping study

This study was performed to investigate iron deposition in the brain of type 2 diabetes mellitus (T2DM) patients using quantitative susceptibility mapping (QSM) and the associated cognitive impairments. Sixty patients diagnosed with T2DM were subjected to neuropsychological tests to determine their cognitive status, and the results were used to subdivide the patients into a T2DM without mild cognitive impairment (MCI) group (n = 30) and a T2DM with MCI group (n = 30). All patients underwent high-resolution susceptibility-weighted imaging, and data processing was performed using SMART (Susceptibility Mapping and Phase Artifacts Removal Toolbox) software. The susceptibility values of the bilateral parietal cortex, frontal white matter, caudate nucleus (CN), putamen (PU), globus pallidus, thalamus, red nucleus, substantia nigra (SN), hippocampus (HP) and dentate nucleus were analyzed and correlated with the neuropsychological cognitive scores. Compared with the normal controls (n = 30), the T2DM without MCI group exhibited significantly increased susceptibility values in the left HP, whereas the T2DM with MCI group showed significantly increased susceptibility values in the bilateral CN, HP, left PU and right SN. Compared with the T2DM without MCI group, the T2DM with MCI group exhibited significantly increased susceptibility values in the right CN, SN and left PU. The susceptibility values for the right CN, SN and left PU were closely correlated with neuropsychological cognitive scores. Our results provide a new relation between T2DM and brain iron deposition and suggested that QSM may be a helpful tool in the detection and evaluation of their cognitive impairment in T2DM.