"Absolute" quantification in Magnetic Resonance Spectroscopy: validation of a clinical protocol in multiple sclerosis

MRS allows to measure cerebral metabolites, thus helping to characterize brain disease diagnosis and follow- up. Metabolite concentration quantification is usually based on metabolite ratio referring to creatine. If this metabolite concentration is supposed to be constant, it may vary in pathological processes. Therefore, ";absolute"; concentration methodology is needed. The aim of this study is to validate a clinical ";absolute"; quantification protocol through the development of an external metabolic phantom, calibration and correction, and the investigation of reproducibility issues. When phantom stability was investigated by a short-term and a long-term reproducibility study, both Standard Deviations (SD) were in agreement with literature values. This ";absolute"; quantification method was applied to patients with multiple sclerosis (MS). The results show a significant decrease in both N-acetyl aspartate (NAA) and choline concentrations.