Background: Material/Methods: Results: Conclusions: O R I G I N A L A R T I C L E Analysis of the brain proton magnetic resonance spectroscopy – differences between normal grey and white matter Paweł Krukowski, Przemysław Podgórski, Maciej Guziński, Paweł Szewczyk, Marek Sąsiadek Department of General Radiology, Interventional Radiology and Neuroradiology, Chair of Radiology, Wrocław Medical University, Wrocław, Poland Author’s address: Marek Sąsiadek, Department of General Radiology, Interventional Radiology and Neuroradiology, Chair of Radiology, Medical University of Wrocław, Borowska 213 Str., 50-556 Wrocław, Poland, e-mail: mareks@rad.am.wroc.pl Summary The proton magnetic resonance spectroscopy (HMRS) is a non-invasive diagnostic method that allows for an assessment of the metabolite concentration in tissues. The sources of the strongest resonance signals within the brain are N-acetylaspartate (NAA), creatine (Cr), choline (Cho), myoinositol (mI) and water. The aim of our study was to analyse the ratios of metabolite signals within the brain in HMRS in the healthy population, to define the differences between the grey and white matter spectra. We studied prospectively 90 subjects aged from 8 to 80 years (mean 43.3 years, SD=17.9), without neurological symptoms or abnormalities in magnetic resonance imaging. In all patients, brain HMRS with Signa HDx 1.5 T MR unit (GE Healthcare) was performed with PRESS sequence, using a single voxel method, at TE of 35 ms and TR of 1500 ms. Spectroscopic evaluation involved voxels placed in the white matter of parietal lobe (PWM) and the grey matter of posterior cingulate gyrus (PGM). On the basis of the intensity of NAA, Cr, Cho, mI and water signals, the proportions of these signals were calculated, as well as the ratio of the analyzed metabolite signal to the sum of signals of NAA, Cho, Cr and mI (%Met) in the PGM and PWM voxels. We compared the proportions in the same patients in PGM and PWM voxels. There has been a statistically significant difference between the proportions of a majority of the metabolite ratios evaluated in PGM and PWM, indicating the higher concentration of NAA, Cr and mI in grey matter, and higher concentration of Cho in white matter. HMRS spectra of the brain grey and white matter differ significantly. The concentrations of NAA, Cr and mI are higher in grey matter, while of choline – in the white matter. Signature: © Pol J Radiol, 2010; 75(2): 22-26 Received: 2010.03.16 Accepted: 2010.03.31 Key words: MR spectroscopy • brain • white matter • grey matter PDF file: http://www.polradiol.com/fulltxt.php?ICID=878512 Background The proton magnetic resonance spectroscopy (HMRS) is a non-invasive diagnostic method that allows for a quantita- tive assessment of the metabolite concentration in tissues, both in vitro and in vivo. Resonance frequency of particular chemical components (metabolites) depends on so called screening effect – i.e. 22 the influence of the electron cloud and chemical bonds sur- rounding the atom. This allows for fission of the spectro- scopic spectrum of the examined sample and identification of particular metabolites. A constant phenomenon is so called chemical shift, s, i.e. a proportional dependence of the resonance frequency of the substances on the value of the external magnetic field B0, under in vivo conditions. It is expressed with a formula: s=(nA–nW)/n0 [1]