Computation of brain metabolite ratios in single-voxel proton MR spectroscopy: comparison between semiautomatic and automatic software

PURPOSE: Metabolite ratios are the measurements most commonly utilised for clinical applications of brain proton magnetic resonance spectroscopy ((1)H-MRS) [1]. We evaluated the agreement between the metabolite ratios calculated with semiautomatic and automatic software. MATERIALS AND METHODS: Two single-voxel spectra (3.375 ml) localised in the frontal grey matter (GM) and peritrigonal white matter (WM) were obtained in 20 healthy subjects by using a point-resolved proton spectroscopy sequence (PRESS, TE=144 ms). The spectra were processed using the semiautomatic software J-Magnetic Resonance User Interface (JMRUI) and the automatic software SpectroView. Agreement of the N-acetyl-aspartate (NAA)/creatine (Cr), NAA/choline (Cho) and Cho/Cr ratios calculated with the two methods was assessed by estimating the 95% limits of agreement (LAs) of the differences of the values obtained with the two software packages. RESULTS: Mean values and standard deviations of NAA/Cr, Cho/Cr and NAA/Cho (semiautomatic//automatic software) were 1.99+/-0.53//1.73+/-0.36, 1.13+/-0.40//1.04+/-0.33, 1.85+/-0.62//1.89+/-0.69 for the GM and 2.24+/-0.41//2.37+/-0.27, 0.96+/-0.17//1.13+/-0.15, 2.37+/-0.43//2.11+/-0.23 for the WM. The 95% LAs were wider for GM spectra and ranged between -0.51, 0.17 for Cho/Cr in the WM and -1.54, 1.47 for NAA/Cho in the GM. CONCLUSIONS: The difference between brain metabolite ratios calculated with the two software packages is not negligible and reflects spectral quality.