ABSTRACT
Direct sodium MRI (23Na-MRI) derives its signal from spin-manipulation of the 23Na nucleus itself and not the more conventional and familiar 1H-MRI. Although present at much lower concentrations in the human body than the 1H nuclei in the water molecule H2O, advances in coil design and pulse sequence development have enabled the feasibility of human in-vivo 23Na-MRI. Additionally,23NaMRI has the potential to offer nuanced physiological insights not available to conventional MRI; this forms the basis of interest in its development, and optimism for its novel clinical utility. 23Na-MRI has potential to be a useful non-invasive imaging technique to assess biochemical and physiologic cellular changes in tissues, e.g. cell integrity and tissue viability. Pathologically, the concentration of total sodium is elevated in tumors relative to normal counterparts due to increased intracellular sodium and/or an increased proportion of extracellular space (reflecting changes in cell morphology and anomalies of homeostasis). Here we review the technological advancements with improved pulse sequences and reconstruction methods that combat the inherent challenges of measuring sodium concentrations in the pediatric brain (in particular, its short tissue T2 value) and present detailed imaging approaches to quantifying sodium concentrations in the pediatric brain that can be assessed in various CNS pathologies, with the focus of this paper on pediatric brain tumors.
ABBREVIATIONS: ECV, extracellular volume fraction; GBCA, gadolinium-based contrast agents; 23Na-MRI, sodium MRI; IBR, iterative Bowsher reconstruction; ISC, intracellular sodium concentration, TSC, total sodium concentration
Footnotes
Dr Roberts discloses remunerated roles on medical/scientific advisory boards for, or consulting positions with, Prism Clinical Imaging, Proteus Neurodynamics, Fieldline Inc. and WestCan Proton Therapy. All other authors declare no conflicts of interest related to the content of this article.
- © 2024 by American Journal of Neuroradiology