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

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.