Metabolic evaluation of human meningiomas by magic angle spinning ex vivo proton magnetic resonance spectroscopy.

High Resolution Magre Angle Spinning (HR-MAS) ex vivo Magnetic Resonance Spectroscopy (MRS) is a powerful tool providing high resolution spectra from human tissues. The quality of the spectra is comparable to that obtained from extracts and the acquisition techniques are the same, with the advantage of carrying out the measurements on intact tissue specimens. The biochemical characterization of human healthy and pathological tissues is thus possible. The specimens were obtained from three patients affected by meningiomas, WHO grade I, with different morphological aspects. Proton HR MAS MR spectra were recorded with a BRUKER Avance400 spectrometer equipped with a HR-MAS probe. Three different types of 1D spectra were acquired by using: i) a composite pulse sequence with water presaturation; ii) a water-suppressed spin-echo sequence; iii) a sequence for diffusion measurements based on stimulated echo and bipolar-gradient pulses. 2D COSY and TOCSY spectra were also acquired. The composite sequence (i) shows the presence in the proton spectra both of low molecular weight metabolites and those arising from macromolecules and lipids; the spin-echo sequence (ii) allows the identification of the resonances arising from small mobile molecules; the third experiment (iii) shows the broad resonances due to macromolecules and lipids. 2D TOCSY and COSY spectra were needed for a full characterization of the metabolic profile of the meningiomas. The spectra (ii) of the meningiomas are quite similar and show the presence of the resonances arising from several low molecular weight metabolites: glutathione, glutammine, isoleucine, valine, leucine, lysine, arginine, threonine, aspartate, glycine, beta-alanine and creatine derivatives), osmolites (taurine, hipo-taurine), carbohydrates and polyols (alfa- and beta-glucose, myoinositol, scylloinositol, mannitol) and chetine containing com- pounds. Moreover, ali the spectra show high relative amounts of alanine, typical of meningiomas. On the contrary, the spectra (i and iii) seem to differentiate the meningiomas: broad components due to triglycerides in one case, to phospholipids in the second and to oligopeptides in the last, respectively, can be observed. The spectroscopic data could be ascribed to the different morphology of these neoplasms.