[A trial for quantification of proton MR spectroscopy: relaxation times of each metabolite and concentration using water signal as an internal standard].

We conducted quantification of proton MR spectroscopy (1H-MRS) using water signal as an internal standard. The 1H-MR spectrum was measured with and without water suppression pulses. For calculation of relaxation times, measurement conditions of the PRESS sequence were as follows: TR = 1500, 3000, 5000 ms, TE = 135,270 ms. The T1 relaxation and T2 relaxation of each metabolite were calculated by fitting to the curve of the equation of the spin echo sequence. The signal intensities of each metabolite were corrected using relaxation times and such corrected intensities were used for the quantitative calculation. The concentration of each metabolite was obtained from ratios of the corrected intensities of water and metabolites. The value of each concentration was coincident with that reported in the previous literature. We considered that this quantification using water signal as an internal standard would be very useful when the proton-weighted image does not show remarkable change.