Absolute quantitation of brain 1H nuclear magnetic resonance spectra. Comparison of different approaches.

ABSTRACT

RATIONALE AND OBJECTIVES: Three different calibration techniques of 1H localized nuclear magnetic resonance (NMR) spectra were applied to a group of healthy volunteers. Absolute concentrations of the metabolites and their standard deviations were compared, and the clinical feasibility of these calibration technique is discussed. METHODS: Eighteen healthy volunteers were included in the study. Both water and creatine were used as internal standard, and a pertinent solution of metabolites was used as an external standard. The T2 relaxation times of the brain metabolites were evaluated in each examination. RESULTS AND CONCLUSIONS: The concentrations obtained using water as an internal standard and using an external standard are very similar, and the first of these methods show smaller standard deviations. The authors' results show that the use of creatine as an internal standard may induce systematic errors in absolute calibration because of the uncertainty on the true creatine concentration.