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

Abstract

Background:23Na 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 using23Na MRI; (2) compare tissue conspicuity of bound sodium concentration (BSC) using23Na 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 echo23Na MRI) were assessed. Results: Twenty-six pediatric patients with gliomas (median age of 12.0 years, range 4.9–23.3 years) were scanned with23Na 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 echo23Na MRI suppressed the sodium signal within both CSF and necrotic foci. Conclusion: Quantitative23Na MRI of pediatric gliomas demonstrates a range of values that are higher than non-neoplastic tissues. Dual echo23Na MRI of BCS improves tissue conspicuity relative to TSC imaging.