Effect of water T2 shortening in the quantification of in-vitro proton MR spectroscopy

Abstract

[Abstract] PURPOSE. This work studies the relationship between in-vitro Proton Magnetic Resonance Spectroscopy metabolite quantification and water T2 decay. MATERIALS AND METHODS. An in-vitro correspondence is established between the iron accumulation and the shortening of water T2 relaxation times using seven spherical phantoms, 6 of them were doped with an increasing concentration of iron metal nanoparticles solution. This is later proposed as a source of error during the LCModel metabolite quantification of either absolute concentrations or ratios. RESULTS. The Pearson's correlation coefficient between water T2 values against absolute metabolite concentrations was on average [r] = 0.97 and on average [r] = 0.85 for metabolite ratios. CONCLUSION. These results suggest that the shortening of T2 values should be taken into account when performing metabolite quantification. Also, the need of demonstrated similar results in in-vivo studies, since the presence of iron deposits or other factors affecting the water T2 decay measurements could explain part of the inter-subject variability in the metabolite concentration and ratio quantification.