Proton magnetic resonance spectroscopy ([sup.1]H MRS) is a useful tool that detects brain metabolites such as NAA (N-acetylaspartate
), a marker for neuronal integrity or neuronal-glial homeostasis; Glx (GABA, glutamine, and glutamate); Cho (choline containing compounds), a measure of cellular density; Cr (creatine plus phosphocreatine), a marker of cellular energy level; and mI (myo-inositol), a marker of brain osmotic balance and glial cells [5, 6].
For gliomas, which represent 75% of all malignant brain tumors, N-acetylaspartate
(NAA) and 2-hydroxyglutarate (2HG) are markers of oncogenesis, and their MS measurement in brain tissue has the potential to improve glioma diagnosis.
After WS, chemical shifts were referenced to the signal intensity of metabolites (N-acetylaspartate
[NAA] at 2.02 part per million [ppm], creatinine (Cr) at 3.01 ppm, and Choat at 3.22 ppm).
A total of 13 metabolites were identified, involving energy metabolism (Cre, creatine; Suc, succinate; Ala, alanine; Lac, lactate), neurotransmitters (Asp, aspartate; Glu, glutamate; Gln, glutamine; GABA, y-aminobutyric acid; Gly, glycine), and membrane metabolism (Cho, choline; NAA, N-acetylaspartate
) as well as osmoregulation (Myo, myoinositol; Tau, taurine).
MRI spectroscopy revealed reduced N-acetylaspartate
concentrations in diabetes patients with multiple episodes of DKA, compared with healthy controls, but no significant differences were seen between diabetes patients with and without DKA.
MR spectroscopy is a non-invasive diagnostic method that can be used for metabolic characterization of brain tumors to better predict the grade of the glioma; based on the analysis of the choline (Cho), N-acetylaspartate
(NAA) and creatine (Crn) peaks.
Our MRS data showed reduced N-acetylaspartate
(NAA) (pless than 0.05) glutamate/glutamine (Glx) (pless than 0.05) and elevated myo-inositol (mI) (pless than 0.05) in the bilateral thalamus during HDT, and all metabolites approached their baseline levels by the fourth scan.
Metabolites measured by [sup.1]H-MRS include N-acetylaspartate
(NAA; a marker of neuronal integrity), choline-containing compounds (Cho; a marker of membrane turnover and glial proliferation), and creatine with phosphocreatine (Cre; a marker of tissue energetic metabolism, usually considered an internal control).
The spectrally selective pulse is based on a Shinnar-Le Roux (SLR) algorithm [2, 5] and was modified to target four metabolites: Lactate (Lac), N-acetylaspartate
(NAA), Creatine (Cre) and Choline (Cho).
MR spectroscopy revealed reduced N-acetylaspartate
, increased lipids, and generalized cortical and subcortical atrophy.
A decrease in N-acetylaspartate
and an increase in myoinositol in the anterior cingulate gyrus are associated with behavioral and psychological symptoms in Alzheimer's disease.
It is important to note that non-enhancing regions may also include tumour as noted on histological analysis.' Metabolic information may be acquired using MR spectroscopy where there is typically a reduction in NAA (N-acetylaspartate
) corresponding to a decreased density of neuronal cells and increased choline as a result of higher cell membrane turnover.'