Ultra-high Resolution in vivo 7T MRI Detects Hippocampal Subfield Iron in Mild Cognitive Impairment and Alzheimer’s Disease

Motivation: Iron dysregulation and deposition may play a role in neurodegeneration in Alzheimer's disease (AD), but limited studies have pushed the boundaries of MRI resolution to accurately quantify iron, particularly in the hippocampus. Goal(s): Utilize ultra-high resolution MRI and QSM for quantitative analysis of hippocampal subfield iron deposition to investigate the role of brain iron in AD. Approach: We acquired 7T multi-echo gradient echo MRI on 19 living human subjects (healthy, mild cognitive impairment, AD) to detect hippocampal source-separated QSM/R2* abnormalities and quantify iron concentrations within hippocampal subfields. Results: Increased R2* and QSM-χ+ was detected in the subiculum-CA1 hippocampal subfields with worsening disease status. Impact: This study successfully performed in vivo ultra-high resolution MRI to quantify iron deposition in hippocampi of MCI and AD patients, contributing to the development of iron as a neuroimaging biomarker for AD.