Proton MR spectroscopy (MRS) consists in the in vivo study of some of the steps involved in brain metabolism. Proton MRS displays low molecular weight brain metabolites in the form of spectra whose shape basically depends on metabolite concentration (more than 0.1-1 mM) which varies in different pathological conditions. Proton MRS is an adjunct to routine MR investigation offering information useful for tissue characterization. The main metabolites detected vary according to the acquisition parameters (TR, TE) and type of impulse sequence adopted (STEAM, PRESS), and include: N-acetyl-aspartate (NAA, neuronal marker) at 2.01 ppm, choline (Cho, membrane marker) at 3.22 ppm, creatine/phosphocreatine (Cr/PCr, cell density index) at 3.5 ppm, myoinositol (mI, glial marker) at 3.56 ppm and when present lactic acid (Lac, anaerobic glycolysis index) and lipids (Lip, necrosis index). Two techniques, single voxel and multivoxel, are used depending on the spatial localisation procedure. Single voxel MRS acquires the spectrum of a preselected brain volume of interest, whereas multivoxel MRS, also known as spectroscopic imaging, acquires the signal from one or more brain sections at the same time in the form of a metabolic map (figures 1-2).