Spectroscopic imaging of glutamate C4 turnover in human brain



One-dimensional spectroscopic imaging of 13C-4-glutamate turnover is performed in the human brain with a 6 cc nominal voxel resolution at 4T. Data were acquired with an indirect detection approach using a short spin echo single quantum 1H-13C heteronuclear editing method and a 7 cm surface coil with quadrature 13C decoupling coils. To analyze the data as a function of tissue type, T1-based image segmentation through the surface coil was performed to determine the gray and white matter contributions to each voxel. The tricarboxylic acid (TCA) cycle rate in gray and white matter was then determined using a two-compartment model with the tissue fractionation derived from the image segmentation. The mean values for the TCA cycle rate for occipital gray and white matter from three volunteers was 0.88 ± 0.12 and 0.28 ± 0.13 respectively, in agreement with literature data. Magn Reson Med 44:673–679, 2000. © 2000 Wiley-Liss, Inc.