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.
OBJECTIVE
To 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.


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, 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).


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.


CONCLUSIONS
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.
Guerrini
Laura
L
Radiodiagnostic Section, Department of Clinical Physiopathology, University of Florence, Florence, Italy.
Belli
Giacomo
G
Mazzoni
Lorenzo
L
Foresti
Silvia
S
Ginestroni
Andrea
A
Della Nave
Riccardo
R
Diciotti
Stefano
S
Mascalchi
Mario
M
D000328:Adult; D000704:Analysis of Variance; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000134:cerebrospinal fluid / Q000378:metabolism; D001921:Brain / Q000378:metabolism* / Q000473:pathology; D002524:Cerebellar Ataxia / Q000134:cerebrospinal fluid* / Q000378:metabolism* / Q000473:pathology; D002531:Cerebellum / Q000378:metabolism / Q000473:pathology; D002794:Choline / Q000134:cerebrospinal fluid / Q000378:metabolism; D003401:Creatine / Q000134:cerebrospinal fluid / Q000378:metabolism; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D009929:Organ Size; D019047:Phantoms, Imaging; D015203:Reproducibility of Results
D001224:Aspartic Acid; C000179:N-acetylaspartate; D003401:Creatine; D002794:Choline