Evaluation of Sodium (23Na) MR-imaging as a Biomarker and Predictor for Neurodegenerative Changes in Patients With Alzheimer's Disease

Abstract

Background/aim: Sodium (²³Na) MR imaging is a noninvasive MRI technique that has been shown to be sensitive to visualize biochemical information about tissue viability, their cell integrity, and cell function in various studies. The aim of this study was to evaluate differences in regional brain ²³Na signal intensity between Alzheimer's disease (AD) and healthy controls to preliminarily evaluate the capability of ²³Na imaging as a biomarker for AD.

Patients and methods: A total of 14 patients diagnosed with AD were included: 12 in the state of dementia and 2 with mild cognitive impairment (MCI), and 12 healthy controls (HC); they were all scanned on a 3T clinical scanner with a double tuned ¹H/²³Na birdcage head coil. After normalizing the signal intensity with that of the vitreous humor, relative tissue sodium concentration (rTSC) was measured after automated segmentation in the hippocampus, amygdala, basal ganglia, white matter (WM) and grey matter (GM) in both cerebral hemispheres.

Results: Patients with AD showed a significant increase in rTSC in comparison to healthy controls in the following brain regions: WM 13.6%; p=0.007, hippocampus 12.9%; p=0.003, amygdala 18.9%; p=0.0007.

Conclusion: ²³Na-MRI has the potential to be developed as a useful biomarker for the diagnosis of AD.

Keywords: 23 Na-MRI; Alzheimer’s disease; biomarkers; dementia; sodium MRI.

Figure 1. Coronal co-registered 23Na images with 3D T1 MPRAGE (a) from a healthy control (b) from an AD patient

Figure 2. Exemplary masks of the different segmented brain region; (a) white matter, (b) basal ganglia, (c) frontal lobe cortex, (d) parietal lobe cortex, (e) occipital lobe cortex, (f) temporal lobe cortex, (g) hippocampus and (h) amygdala