MRI for Iron Mapping in Alzheimer's Disease

<b><i>Background:</i></b> Monitoring iron deposition became possible with new dedicated quantitative MRI sequences. These sequences hold promise to determine the role of iron in Alzheimer's disease (AD). It is currently unclear as to whether iron accumulation is pathogenically involved in AD or solely represents an epiphenomenon of the neurodegenerative process. <b><i>Objective:</i></b> We discuss currently available MR methods for quantitative iron mapping in the brain and provide an overview of results in animal models as well as in AD patients. <b><i>Methods:</i></b> A short literature review was used for analysis. <b><i>Results:</i></b> R2*-based imaging is the best validated technique for iron detection. Current research applications include amyloid plaque detection in postmortem brains and in transgenic animal models and quantitative iron mapping in gray matter. AD patients have increased iron levels in the putamen, pulvinar thalamus, red nucleus, hippocampus, and temporal cortex. The clinical consequences of this finding and the dynamics of iron accumulation in AD are widely unknown. <b><i>Conclusions:</i></b> MRI allows to quantitatively map iron accumulation in the brain. The clinical significance of increased iron levels in AD needs to be determined in both cross-sectional and longitudinal studies. The advent of ultra-high field imaging in clinical applications will increase image resolution and will allow in vivo iron detection in neocortical structures in AD patients both cross-sectionally and longitudinally.