Oxygen extraction fraction (OEF) in the brain can be obtained by Quantitative Susceptibility Mapping (QSM). QSM can also estimate iron which is implicated in the pathogenesis of Alzheimer’s disease and its pre-symptomatic antecedents. The differences of OEF and iron values among the controls, Mild Cognitive Impairment and AD were investigated by ROI based comparisons using a one-way analysis of variance. These values in the posterior brain regions were found to have a trend towards increment in patient groups compared with controls, in this pilot study. Future studies are required to validate the usefulness of this technique as potential biomarker.