On the magnetic field dependence of deuterium metabolic imaging

Deuterium metabolic imaging (DMI) is a novel MR-based method to spatially map metabolism of deuterated substrates such as [6,6'-² H₂ ]-glucose in vivo. Compared with traditional ¹³ C-MR-based metabolic studies, the MR sensitivity of DMI is high due to the larger ² H magnetic moment and favorable T₁ and T₂ relaxation times. Here, the magnetic field dependence of DMI sensitivity and transmit efficiency is studied on phantoms and rat brain postmortem at 4, 9.4 and 11.7 T. The sensitivity and spectral resolution on human brain in vivo are investigated at 4 and 7 T before and after an oral dose of [6,6'-² H₂ ]-glucose. For small animal surface coils (Ø 30 mm), the experimentally measured sensitivity and transmit efficiency scale with the magnetic field to a power of +1.75 and -0.30, respectively. These are in excellent agreement with theoretical predictions made from the principle of reciprocity for a coil noise-dominant regime. For larger human surface coils (Ø 80 mm), the sensitivity scales as a +1.65 power. The spectral resolution increases linearly due to near-constant linewidths. With optimal multireceiver arrays the acquisition of DMI at a nominal 1 mL spatial resolution is feasible at 7 T.