Quantitative magnetic susceptibility assessed by 7T magnetic resonance imaging in Alzheimer's disease caused by streptozotocin administration

Streptozotocin treatment has emerged as an alternative model of sporadic Alzheimer's disease (SAD). Streptozotocin-induced alterations in iron and calcium levels reflect magnetic susceptibility changes, while susceptibility distribution in the cerebral regions has not been reported yet. This study aimed to investigate susceptibility distribution in the limbic system after streptozotocin administration to cynomolgus monkeys for exploring informative SAD biomarkers. Quantitative susceptibility mapping (QSM) using 7T magnetic resonance imaging (MRI) was utilized to quantitatively compare the susceptibility distributions in monkeys with sporadic Alzheimer disease and age-matched healthy controls. Compared to healthy controls, overall susceptibility values differed in the SAD models. Notable substantial susceptibility changes were observed in the hypothalamus with a 4.38-time decrease (AD: -47.45 +/- 12.19 ppb, healthy controls: 14.02 +/- 9.51 ppb) and in the posterior parts of the corpus callosum with a 2.83-times increase (AD: 31.49 +/- 15.90 ppb; healthy controls: 11.13 +/- 4.02 ppb). These susceptibility alterations may reflect neuronal death, and could serve as key biomarkers in the SAD. These results may be useful for specifying AD pathologies such as cognitive and non-cognitive symptoms.