TY - JOUR
T1 - T2 measurement and quantification of glutamate in human brain in vivo
AU - Choi, Changho
AU - Coupland, Nicholas J.
AU - Bhardwaj, Paramjit P.
AU - Kalra, Sanjay
AU - Casault, Colin A.
AU - Reid, Kim
AU - Allen, Peter S.
PY - 2006/11/1
Y1 - 2006/11/1
N2 - The proton NMR transverse relaxation time T2 of glutamate (Glu) in human brain was measured by means of spectrally selective refocusing at 3.0 T in vivo. An 81.4-ms-long dual-band Gaussian 180° RF pulse, designed for refocusing at 2.35 and 3.03 ppm, was employed within point-resolved spectroscopy (PRESS) to generate the Glu C4-proton target multiplet and the total creatine (tCr) singlet. Six optimal echo times (TEs) between 128 and 380 ms were selected from numerical analysis of the filtering performance for effective detection of the Glu signal with minimal contamination from glutamine (Gln), N-acetylaspartate (NAA), and glutathione (GSH). The magnetization of Glu and tCr was extracted from spectral fitting of experimental and calculated spectra. Apparent T2 values of Glu and tCr were estimated as 201 ± 18 and 164 ± 12 ms for the medial prefrontal (PF) cortex, and 198 ± 22 and 169 ± 15 ms (mean ± SD, N = 5) for the left frontal (LF) cortex, respectively. With water segmentation data, the magnetization values of Glu and tCr of the two adjacent voxels, calculated from the T2 values and spectra following the thermal equilibrium magnetization, were combined to give the Glu and tCr concentrations as 10.37 ± 1.06 and 8.87 ± 0.56 mM for gray matter (GM), and 5.06 ± 0.57 and 5.16 ± 0.45 mM (mean ± SD, N = 5) for white matter (WM), respectively.
AB - The proton NMR transverse relaxation time T2 of glutamate (Glu) in human brain was measured by means of spectrally selective refocusing at 3.0 T in vivo. An 81.4-ms-long dual-band Gaussian 180° RF pulse, designed for refocusing at 2.35 and 3.03 ppm, was employed within point-resolved spectroscopy (PRESS) to generate the Glu C4-proton target multiplet and the total creatine (tCr) singlet. Six optimal echo times (TEs) between 128 and 380 ms were selected from numerical analysis of the filtering performance for effective detection of the Glu signal with minimal contamination from glutamine (Gln), N-acetylaspartate (NAA), and glutathione (GSH). The magnetization of Glu and tCr was extracted from spectral fitting of experimental and calculated spectra. Apparent T2 values of Glu and tCr were estimated as 201 ± 18 and 164 ± 12 ms for the medial prefrontal (PF) cortex, and 198 ± 22 and 169 ± 15 ms (mean ± SD, N = 5) for the left frontal (LF) cortex, respectively. With water segmentation data, the magnetization values of Glu and tCr of the two adjacent voxels, calculated from the T2 values and spectra following the thermal equilibrium magnetization, were combined to give the Glu and tCr concentrations as 10.37 ± 1.06 and 8.87 ± 0.56 mM for gray matter (GM), and 5.06 ± 0.57 and 5.16 ± 0.45 mM (mean ± SD, N = 5) for white matter (WM), respectively.
KW - Double-banded 180° RF pulse
KW - Glutamate
KW - Gray matter
KW - Human brain
KW - Prefrontal
KW - Proton MRS
KW - Spectrally-selective refocusing
KW - Transverse relaxation time T
KW - White matter
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U2 - 10.1002/mrm.21055
DO - 10.1002/mrm.21055
M3 - Article
C2 - 17029225
AN - SCOPUS:33750624344
SN - 0740-3194
VL - 56
SP - 971
EP - 977
JO - Magnetic resonance in medicine
JF - Magnetic resonance in medicine
IS - 5
ER -