Imaging of sodium in the brain: a brief review

• Published in: NMR in biomedicine 2016-02, Vol.29 (2), p.162-174
• Main Authors: Shah, N. Jon, Worthoff, Wieland A., Langen, Karl-Josef
• Format: Article
• Language: English
• Subjects: acquisition methods; applications; Brain - anatomy & histology; Brain Mapping; clinical applications; Diagnostic Imaging - methods; Humans; Magnetic Resonance Imaging; MR-PET hybrid imaging; neurological; neuroscience; Positron-Emission Tomography; Sodium - metabolism; sodium imaging
• ISSN: 0952-3480; 1099-1492
• DOI: 10.1002/nbm.3389

Sodium‐based MRI plays a vital role in the study of metabolism and can unveil valuable information about emerging and existing pathology – in particular in the human brain. Sodium is the second most abundant MR active nucleus in living tissue and, due to its quadrupolar nature, has magnetic properties not common to conventional proton MRI, which can reveal further insights, such as information on the compartmental distribution of intra‐ and extracellular sodium. Nevertheless, the use of sodium nuclei for imaging comes at the expense of a lower sensitivity and significantly reduced relaxation times, making in vivo sodium studies feasible only at high magnetic field strength and by the use of dedicated pulse sequences. Hybrid imaging combining sodium MRI and positron emission tomography (PET) simultaneously is a novel and promising approach to access information on dynamic metabolism with much increased, PET‐derived specificity. Application of this new methodology is demonstrated herein using examples from tumour imaging. Copyright © 2015 John Wiley & Sons, Ltd. The distribution and concentrations of sodium are indicators of pathology, which can be imaged non‐invasively and in vivo using MRI. We discuss and compare different imaging techniques suitable for sodium imaging, including methods for differentiating between the intracellular/extracellular compartments and MR‐PET. Applications to brain imaging are presented, with an emphasis on neurological disorders and diseases. Figure from Fiege et al. ().