Purpose: We herein present a spectroscopic technique for the
detection of scalar-coupled metabolites based on stimulated
echo acquisition mode (STEAM). The method is based on the
time evolution of scalar-coupled metabolites at different mixing
times and a constant echo time. The technique is optimized
for targeting the metabolite glutamate at 7T.
Methods: Numerical simulations were used to optimize the
parameters to maximize the chosen metabolite signal. The maximum
detection efficiency and metabolite signal as a function of
echo time were used to identify the optimal parameters. In vitro
and in vivo validations of the method were also performed.
Results: This method canceled all the strong singlet lines and
signals from macromolecules and preserved signals originating
from the scalar-coupled metabolites. The subtracted spectrum
was strongly simplified, but the complete spectral information
of the traditional STEAM acquisition was retained in the sum
spectrum.
Conclusions: The simulations performed in this study were in
agreement with the experimental results, and a clear detection
of the metabolite of interest was obtained. The applicability in
vivo was also demonstrated, with the selective detection of glutamate
in human brain. This technique is simple, suitable for
standard MR systems without sequence programming and
could be used to detect other metabolites