We implemented methods for localized shimming and eddy current evaluation [20]. These methods significantly improved localized 1H spectroscopy at 4T. Water linewidth in the occipital lobe consistently between 7 and 9 Hz and the metabolite linewidth (creatine methyl at 3.04 ppm) was between 5.6 and 7.4 Hz was achieved. With these linewidths, ?-D-glucose H1 resonance at 5.23 ppm was reliably observed with a second-order baseline residual due to the water. The quantification of cerebral glucose was performed by comparing the intensity of the ?-D-glucose peak at 5.23 ppm with the methyl peak of 10 mM creatine over a wide range from 5 to 30 mM plasma glucose. In the last year of funding a separate study using the aforelisted capabilities, we observed that brain glucose was proportional to plasma glucose which is not consistent with previously reported kinetic constants using the standard Michaelis-Menten model. Instead we proposed that brain glucose transport kinetics are best described by including reversible Michaelis-Menten kinetics.
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