Prospects for deuterium MR spectroscopy for assessing amino acid metabolism in neuro-oncology

Recently, deuterium MR spectroscopy (DMRS), has gained attention in bothclinical and preclinical settings for studying brain metabolism in healthy volunteersand patients with neuro-oncological conditions. DMRS can surpass the results of thegold standard metabolic imaging technique, positron emission tomography (PET)with amino acids tracers, which are considered to be tumor proliferation markers. Inthis article, we consider the potential utility of deuterated amino acids in assessingcellular metabolism akin to PET tracers.The aim of this study is to assess the feasibility a 3.0T clinical MR scanner toacquire deuterium spectra from phantoms containing a deuterated α-aminoisobutyricacid (AIB) tracer and determine its minimal concentration that can be detected.We carried out DMRS on phantoms containing deuterated tracers using a single-channel 1H-2H RF-coil (Rapid Biomedical GmbH) on a 3.0T MR scanner (GEHealthcare, Milwaukee, WI, USA). The phantom comprised a 1.5-liter plasticcontainer filled with natural water, housing a cylinder-shaped vial containingdeuterated AIB tracer (Solvex LLC, Moscow, Russia) positioned at the center of thecontainer. Vials of volumes 20, 12, and 6 mL were tested, with tracer concentrationsranging from 0.38 to 20 mM. Deuterium 2D spectra with a voxel grid of 20x20 wereobtained using a custom pulse sequence “fidall”. Scanning durations were 34:21 or17:10 minutes. A localized 2H-MR spectrum was analyzed for the voxel with thehighest signal amplitude.The spectra exhibited two distinct peaks of water and AIB. The lowest tracerconcentration at which both peaks were distinguishable was 1.25 mM for all testedvials.Thus, DMRS can measure AIB concentrations as low as 1.25 mM in 6-mL testobjects using a 3.0T scanner. This concentration corresponds to the level of aminoacid accumulation observed in neuro-oncological tumors. It proves that AIB haspotential as a tracer for DMRS in tumor diagnostics.