Quantitative Sodium ((23)Na) MRI in Pediatric Gliomas: Initial Experience

Background: (23)Na MRI correlates with tumor proliferation, and studies in pediatric patients are lacking. The purpose of the study: (1) to compare total sodium concentration (TSC) between pediatric glioma and non-neoplastic brain tissue using (23)Na MRI; (2) compare tissue conspicuity of bound sodium concentration (BSC) using (23)Na MRI dual echo relative to TSC imaging. Methods: TSC was measured in: (1) non-neoplastic brain tissues and (2) three types of manually segmented gliomas (diffuse intrinsic brainstem glioma (DIPG), recurrent supratentorial low-grade glioma (LGG), and high-grade glioma (HGG)). In a subset of patients, serial changes in both TSC and BSC (dual echo (23)Na MRI) were assessed. Results: Twenty-six pediatric patients with gliomas (median age of 12.0 years, range 4.9–23.3 years) were scanned with (23)Na MRI. DIPG treated with RT demonstrated higher TSC values than the uninvolved infratentorial tissues (p < 0.001). Recurrent supratentorial LGG and HGG exhibited higher TSC values than the uninvolved white matter (WM) and gray matter (GM) (p < 0.002 for LGG, and p < 0.02 for HGG). The dual echo (23)Na MRI suppressed the sodium signal within both CSF and necrotic foci. Conclusion: Quantitative (23)Na MRI of pediatric gliomas demonstrates a range of values that are higher than non-neoplastic tissues. Dual echo (23)Na MRI of BCS improves tissue conspicuity relative to TSC imaging.