Dynamic observation of 2H labeled compounds in the human brain with 1H versus 2H magnetic resonance spectroscopy at 9.4T
The metabolic pathway of [6,6-2H2]-labeled glucose was investigated with two different techniques. The first technique used direct detection of deuterium applying Deuterium Metabolic Imaging (DMI). The second technique used the indirect detection of deuterium with proton MR spectroscopy (MRS) called Quantitative Exchanged-label Turnover (QELT) MRS. For the first time, time-resolved data was acquired for both techniques in the same healthy human subjects and directly compared. The time-curves were used in a kinetic model to estimate rates of the metabolic pathway of glucose. Two different kinetic models were compared. One included only DMI data, the second one combined DMI and QELT. For the first model, a tricarboxylic acid (TCA) cycle rate of 0.69 {+/-} 0.10 mol{middle dot}min-1{middle dot}g-1 was determined. For the second model, the estimated TCA cycle rate was 0.68 {+/-} 0.12 mol{middle dot}min-1{middle dot}g-1. In addition, the rate of glutamine synthesis from glutamate could be estimated with model 2 (0.51 {+/-} 0.15 mol{middle dot}min-1{middle dot}g-1). The sensitivity of both methods was evaluated and compared to alternative techniques.