Assessment of glutamate and glutamine contribution to in vivo N-acetylaspartate quantification in human brain by (1)H-magnetic resonance spectroscopy.
N-Acetylaspartate (NAA) is one of the most important metabolites detectable by brain (1)H-MRS being considered an index of neuronal integrity. At the low magnetic field used in most clinical settings beta,gamma-glutamate/glutamine (Glx) resonances are very close and partially overlap the methyl-NAA resonance interfering with NAA quantification especially at low TE and in the presence of increased Glx signals. NAA overestimation due to Glx on a set of model solutions containing NAA, glutamate, and glutamine in variable amounts was evaluated and the result tested in vivo in six healthy controls and five age- and sex-matched patients with hepatic encephalopathy (HE), the latter having an increased Glx content. A method to assess in vivo the NAA overestimation caused by Glx is proposed. A perfect match was obtained between the assessment of Glx contamination on the NAA of healthy controls and that obtained on the model solutions. However, a substantial difference in NAA overestimation was found between controls and HE patients that cannot be explained by our model. An interpretative hypothesis is provided.
Clementi
Valeria
V
Biochimica Clinica, Dipartimento di Medicina Clinica e Biotecnologia Applicata "D Campanacci," Università di Bologna, Bologna, Italy.
Tonon
Caterina
C
Lodi
Raffaele
R
Malucelli
Emil
E
Barbiroli
Bruno
B
Iotti
Stefano
S
D000465:Algorithms; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000032:analysis; D015415:Biomarkers / Q000032:analysis; D001921:Brain / Q000378:metabolism*; D003936:Diagnosis, Computer-Assisted / Q000379:methods; D005260:Female; D018698:Glutamic Acid / Q000032:analysis*; D005973:Glutamine / Q000032:analysis*; D006501:Hepatic Encephalopathy / Q000175:diagnosis* / Q000378:metabolism*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D015415:Biomarkers; D005973:Glutamine; D001224:Aspartic Acid; D018698:Glutamic Acid; C000179:N-acetylaspartate