Uncovering the specificity of quantitative MRI to different molecular forms of iron in the brain. 

The main iron compounds, ferritin and transferrin, are distributed heterogeneously across the brain and are often implicated in neurodegenerative diseases. While quantitative MRI has been linked to brain tissue’s microstructure, non-invasive discrimination between iron forms still remains a challenge. We propose an in vivo approach for assessing brain iron forms, based on the dependency of R1 on R2*. We establish this approach in phantoms and validate it against histology. In the in vivo human brain, the dependency of R1 on R2*, rather than each parameter by itself, predicts the inhomogeneous distribution of iron-binding proteins with age and across brain regions.