Impact of cerebrospinal fluid contamination on brain metabolites evaluation with ¹H-MR spectroscopy: A single voxel study of the cerebellar vermis in patients with degenerative ataxias.

Guerrini, Laura; Belli, Giacomo; Mazzoni, Lorenzo; Foresti, Silvia; Ginestroni, Andrea; Della Nave, Riccardo; Diciotti, Stefano; Mascalchi, Mario

Purpose To investigate the impact of cerebrospinal fluid (CSF) contamination on metabolite evaluation in the superior cerebellar vermis with single-voxel 1H-MRS in normal subjects and patients with degenerative ataxias. Materials and Methods Twenty-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, T2 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). Results In 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. Conclusion CSF 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. J. Magn. Reson. Imaging 2009;30:11-17. © 2009 Wiley-Liss, Inc.

Journal of Magnetic Resonance Imaging, 2009, Vol 30, Issue 1, p11

1053-1807

Academic Journal

10.1002/jmri.21804