Transverse relaxation time constants of the five major metabolites in human brain measured in vivo using LASER and PRESS at 3 T

Purpose: The goal of this study was to measure and compare the apparent transverse relaxation time constants (T₂) of five intracellular metabolites using localization by adiabatic selective refocusing (LASER) and point-resolved spectroscopy (PRESS) sequences in the human brain at 3 T. Methods: Five healthy subjects were studied at 3 T. ¹H spectra from the prefrontal cortex were acquired at six different echo times using LASER and PRESS sequences. Postprocessed data were analyzed with LCModel, and the resulting amplitudes were fitted using a mono-exponential decay function to determine the T₂ of metabolites. Results: Twenty-one percent higher apparent T₂ values for the singlet resonances of N-acetyl aspartate, total creatine, and total choline were measured with LASER as compared with PRESS, whereas comparable apparent T₂ values were measured for strongly coupled metabolites, glutamate, and myo-inositol, with both sequences. Conclusions: Reliable T₂ measurements were obtained with both sequences for the five major intracellular metabolites. The LASER sequence appears to be more efficient in suppressing the diffusion component for singlets (having nonexchangeable protons) compared to J-coupled metabolites. Magn Reson Med 79:1260–1265, 2018.