• Laura Guerrini, Giacomo Belli, Lorenzo Mazzoni, Silvia Foresti, Andrea Ginestroni, Riccardo Della Nave, Stefano Diciotti, and Mario Mascalchi.
• Radiodiagnostic Section, Department of Clinical Physiopathology, University of Florence, Florence, Italy.
• J Magn Reson Imaging. 2009 Jul 1; 30 (1): 11-7.

PurposeTo investigate the impact of cerebrospinal fluid (CSF) contamination on metabolite evaluation in the superior cerebellar vermis with single-voxel (1)H-MRS in normal subjects and patients with degenerative ataxias.Materials And MethodsTwenty-nine healthy volunteers and 38 patients with degenerative ataxias and cerebellar atrophy were examined on a 1.5 Tesla scanner. Proton spectra of a volume of interest placed in the superior vermis were acquired using a four TE PRESS technique. We calculated N-acetyl aspartate (NAA)/creatine (Cr), choline (Cho)/Cr, and NAA/Cho ratios, T(2) relaxation times and concentrations of the same metabolites using the external phantom method. Finally, concentrations were corrected taking into account the proportion of nervous tissue and CSF, that was determined as Volume Fraction (VF).ResultsIn healthy subjects, a significant difference was observed between metabolite concentrations with and without correction for VF. As compared to controls, patients with ataxias showed significantly reduced NAA/Cr and NAA concentrations, while only corrected Cr concentration was significantly increased. The latter showed an inverse correlation with VF.ConclusionCSF contamination has a not negligible effect on the estimation of brain metabolites. The increase of Cr concentration in patients with cerebellar atrophy presumably reflects the substitutive gliosis which takes place along with loss of neurons.(c) 2009 Wiley-Liss, Inc.

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