H-1 MR Spectroscopy of Meningiomas at 3.0T: the Role of Glutamate-Glutamine Complex and Glutathione

Proton magnetic resonance spectroscopy (H-1 MRS) has been used extensively for the characterization of the intracranial meningiomas. A major emphasis is placed on identification of an alanine (Ala) content within these tumors. Less attention is given to other metabolites such as glutamine and glutamate (Glx). Our objective was to assess the incidence and the relevance of the Glx content in meningiomas, to evaluate their usefulness versus Ala in the diagnosis of intracranial meningiomas and to indicate a potential role of other biochemical compounds such as glutathione (GSH). We performed a retrospective review of the H-1 MRS spectra at 3.0T of 16 intracranial meningiomas in 16 consecutive patients with newly diagnosed tumors. All meningiomas were evaluated with single-voxel H-1 MRS at short echo time using an automatic quantitation of the metabolites by linear combination model (LCModel) fitting. Detailed analysis of the spectra showed that the Glx content was a more common result (100%) than the Ala content (44%). The Glx content can be considered in high concentrations within these tumors resulting in overall levels comparable to normal brain values (P > 0.2). A glutathione (GSH) spectrum was added to the LCModel basis set in six meningiomas and in all of them a GSH peak was detected at 2.95 ppm (100%). Other metabolites such as guanidinoacetate (Gua) were detected in six meningiomas (38%) and this was not reported previously. Our data indicate that Glx and GSH are far more likely to be biochemical predictors than Ala in the H-1 MRS evaluation of intracranial meningiomas. The significance of Gua as another potential marker of the meningioma cell metabolism needs to be further investigated.