Quantitative brain proton MR spectroscopy based on measurement of the relaxation time T1 of water

Abstract

Purpose: To provide a straightforward method for metabolite quantitation in the brain. Tissue water concentration can be determined in a voxel by measuring T(1) and it may provide an internal reference for the calculation of the metabolite concentrations.

Materials and methods: Water-suppressed stimulated echo acquisition mode spectra were obtained at 1.5T, and the tissue water content was calculated from T(1).

Results: The calculated water content values demonstrated very good agreement with literature data. Metabolite concentrations (mmol/liter) in the gray and white matter: N-acetyl-aspartate = 14.02 +/- 1.93, creatine = 9.98 +/- 1.03, and choline = 1.14 +/- 0.24; N-acetyl-aspartate = 11.08 +/- 2.24, creatine = 7.83 +/- 0.66, and choline = 2.05 +/- 0.38, respectively.

Conclusion: The water content calculated from T(1) can yield an internal reference in MR spectroscopy, and the accurate measurement of metabolite concentrations is feasible. The proposed method is simple and can readily be applied in any MR center without the need for complicated corrections or calibration procedures.