ReviewSodium imaging as a marker of tissue injury in patients with multiple sclerosis

- There is experimental evidence that sodium dyshomeostasis is associated with axonal degeneration in MS.
- Novel developments in MRI methods at high and ultra-high field strength allow measurement of sodium signal in vivo.
- More sophisticated MRI methods allow measurement of intra- and extra-cellular sodium concentration in vivo.
- Sodium concentration is increased in lesions and brain normal-appearing tissue in MS patients.
- Preliminary studies suggest that increased sodium concentration correlates moderately with the EDSS score.

Recent studies have suggested that intra-axonal sodium accumulation contribute to axonal degeneration in patients with MS. Advances in MRI hardware and software allow acquisition of brain sodium signal in vivo. This review begins with a summary of the experimental evidence for impairment of sodium homeostasis in MS. Then, MRI methods for sodium acquisition are reviewed and the application of the techniques in patients with MS is discussed. Sodium imaging and ultra-high field MRI have the potential to provide tissue-specific markers of neurodegeneration in MS.