The evaluation of iron content in Alzheimer’s disease by magnetic resonance imaging: Phase and R2* methods

Abstract

Background: Magnetic resonance imaging (MRI) is the best imaging examination to evaluate abnormal iron deposition in the brain. Although phase of susceptibility weighted imaging (SWI) and R2* values have been used to probe iron deposition in Alzheimer’s disease (AD) brain, no study has exploited both techniques for quantification of iron deposition in AD. Purpose: Use phase and R2* to evaluate iron changes in AD brain. Investigate the correlation of two methods with the severity of cognitive impairment in AD patients.Materials and methods: Twenty-three patients with AD and eighteen normal controls underwent SWI and multi-echo gradient recalled-echo (GRE) imaging on a 3T MR scanner. The phase values from SWI and R2* values calculated from multi-echo GRE imaging of bilateral hippocampus, globus pallidus, putamen, caudate nucleus, thalamus, substantia nigra, red nucleus and dentate nucleus were evaluated. Results: In AD group, the phase values of bilateral hippocampus, globus pallidus, caudate nucleus, substantia nigra and left putamen were significantly lower than the control group. The R2* values of bilateral hippocampus, caudate nucleus, putamen and right globus pallidus were significantly higher than the control group. The phase and R2* values of the left putamen had the most significant correlation with mini-mental state examination (MMSE) scores in AD patients. Conclusion: The SWI phase value and R2* value can be used as effective methods to study the abnormality of iron deposition in AD brain, wherein phase had advantages in small brain structure. Phase value showed a higher correlation coefficient with MMSE scores, moreover the iron deposition of left putamen has a close relationship with the progression of AD.