Metabolite concentrations in Magnetic Resonance Spectroscopy (MRS) are determined by analyzing the intensity or area under the curve (AUC) of specific peaks in the MRS spectrum, which correspond to different metabolites in the brain. MRS uses the magnetic properties of hydrogen protons (1H) in metabolites like N-Acetyl Aspartate (NAA), Choline (Cho), and Creatine (Cre) to generate a spectrum. The position (chemical shift) of these peaks in the spectrum reflects the unique chemical environment of the protons within the metabolites, while the area under each peak represents the concentration of that metabolite in the voxel being studied (Provencher, 2001; Choi, 2006).
In order to quantify metabolite concentrations, MRS data is processed to compare the in vivo spectra to a set of model spectra derived from known metabolite concentrations. This method accounts for variations in baseline and noise, providing a more accurate measurement of metabolite levels. Water or creatine is often used as an internal reference standard to normalize the data, thereby allowing for more consistent and comparable results across different scans and individuals (Ross, 2004; Buonocore, 2015). The resulting metabolite ratios, such as NAA/Cre or Cho/Cre, are then used to assess neuronal health and detect abnormalities in brain regions affected by diseases, such as CBD.