Low-grade glioma: Correlation of short echo time 1H-MR spectroscopy with 23Na MR imaging

Abstract

BACKGROUND AND PURPOSE: There is considerable variability in the clinical behavior and treatment response of low-grade (WHO grade II) gliomas. The purpose of this work was to characterize the metabolic profile of low-grade gliomas by using short echo time 1H-MR spectroscopy and to correlate metabolite levels with MR imaging-measured sodium (23Na) signal intensity. Based on previous studies, we hypothesized decreased N-acetylaspartate (NAA) and increased myo-inositol (mlns), choline (Cho), glutamate (Glu), and 23Na signal intensity in glioma tissue. MATERIALS AND METHODS: Institutional ethics committee approval and informed consent were obtained for all of the subjects. Proton (1H-MR) spectroscopy (TR/TE = 2200/46 ms) and sodium (23Na) MR imaging were performed at 4T in 13 subjects (6 women and 7 men; mean age, 44 years) with suspected low-grade glioma. Absolute metabolite levels were quantified, and relative 23Na levels were measured in low-grade glioma and compared with the contralateral side in the same patients. Two-sided Student t tests were used to test for statistical significance. RESULTS: Significant decreases were observed for NAA (P < .001) and Glu (P = .004), and increases were observed for mlns (P = .003), Cho (P = .025), and sodium signal intensity (P < .001) in low-grade glioma tissue. Significant correlations (r2 > 0.25) were observed between NAA and Glu (P < .05) and between NAA and mlns (P < .01). Significant correlations were also observed between 23Na signal intensity and NAA (P < .01) and between 23Na signal intensity and Glu (P