Meng Gu1,
Natalie M. Zahr2,3, Daniel M. Spielman1, Edith V.
Sullivan2,3, Adolf Pfefferbaum2,3, Dirk Mayer1,3
1Radiology, Stanford University,
Stanford, CA, United States; 2Psychiatry & Behavioral
Sciences, Stanford University, Stanford, CA, United States; 3Neuroscience
Program, SRI International, Menlo Park, CA, United States
Quantifying
and separating glutamate (Glu) and glutamine (Gln) using conventional
magnetic resonance spectroscopy on clinical scanners is challenging.
Constant-time point-resolved spectroscopy was developed at 3T to detect Glu
but does not resolve Gln. To quantify Glu and Gln separately, a time-domain
basis set was constructed taking into account T2 relaxation and dephasing
from B0 inhomogeneity. Metabolite concentrations were estimated by fitting
the basis magnitude spectrum to the measured spectrum. This method was
validated using phantoms with different Glu and Gln concentrations. When
applied to in vivo data, ethanol-exposed but not control rats showed
increased Gln after exposure.