Optimized diffusion-weighted spectroscopy for measuring brain glutamate apparent diffusion coefficient on a whole-body MR system.
A diffusion-weighted stimulated echo acquisition mode sequence was implemented in order to measure the glutamate apparent diffusion coefficient (ADC) in the monkey brain on a whole-body 3 T system. TE and TM were adjusted for maximizing glutamate signal intensity. Glutamate ADC was measured in a 5.8 mL voxel made of gray and white matter in macaque monkeys. The effect of post-processing on the estimated ADC was carefully assessed and appeared to be critical. Individual scan phasing and macromolecule subtraction corrected for approximately 25% and approximately 15% biases in glutamate ADC, respectively. Proper data processing yielded ADC values of 0.21 +/- 0.03 microm(2)/ms for glutamate, 0.15 +/- 0.04 microm(2)/ms for N-acetylaspartate + N-acetylaspartylglutamate, 0.12 +/- 0.03 microm(2)/ms for creatine, 0.11 +/- 0.05 microm(2)/ms for choline and 0.18 +/- 0.04 microm(2)/ms for myo-inositol.
Valette
Julien
J
CEA-SHFJ, Orsay, France.
Guillermier
Martine
M
Besret
Laurent
L
Boumezbeur
Fawzi
F
Hantraye
Philippe
P
Lebon
Vincent
V
D000818:Animals; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D001921:Brain / Q000033:anatomy & histology / Q000378:metabolism*; D001923:Brain Chemistry; D002794:Choline / Q000378:metabolism; D003401:Creatine / Q000378:metabolism; D004058:Diffusion; D038524:Diffusion Magnetic Resonance Imaging; D018698:Glutamic Acid / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D007294:Inositol / Q000378:metabolism; D008251:Macaca
D001224:Aspartic Acid; D018698:Glutamic Acid; D007294:Inositol; C000179:N-acetylaspartate; D003401:Creatine; D002794:Choline