Comparison of the Metabolic Profile of a Healthy Brain on Two VIDA Siemens 3T MR Tomographs

Aim: The aim of this study was to determine whether brain metabolite concentrations measured on Siemens Magnetom VIDA 3T MR tomographs at two different MR units are comparable. Subjects and methods: We measured a group of identical healthy volunteers at both sites over a 24-h period using proton single voxel spectroscopy and MR spectroscopic imaging. We calculated the relative asymmetry in metabolic concentrations and their ratios between tomographs and between hemispheres in various brain regions. Results: Bland-Altman plots showed no significant differences in any of the parameters evaluated between the two tomographs or between the left and right hemispheres. Signal-to-noise ratios were comparable at both sites. The most frequently measured metabolite concentrations (total N-acetylaspartate, total creatine, choline-containing compounds) and their ratios showed diff erences between tomographs and between hemispheres averaging up to 6% using both short and long echo times for both single voxel MR spectroscopy and spectroscopic imaging. Myo-inositol exhibited a greater difference between hemispheres (max. 14%). Conclusion: Metabolic concentrations and their ratios were comparable at both MR units regardless of the MRI spectroscopic method and sequence echo time. To quantitatively compare the metabolic profiles of patients with control values, it is sufficient to measure only one set of control data and then use this at both sites. The data obtained can also be pooled in multicenter studies.