Integrating 1H MRS and deuterium labeled glucose for mapping the dynamics of neural metabolism in humans

In the technique presented here, dubbed 'qMRS', we quantify the change in H-1 MRS signal following administration of H-2-labeled glucose. As in recent human DMRS studies, we administer [6,6'-H-2(2)]-glucose orally to healthy subjects. Since H-2 is not detectable by H-1 MRS, the transfer of the H-2 label from glucose to a downstream metabolite leads to a reduction in the corresponding H-1 MRS resonance of the metabolite, even if the total concentration of both isoforms remains constant. Moreover, introduction of the deuterium label alters the splitting pattern of the proton resonances, making indirect detection of the deuterated forms- as well as the direct detection of the decrease in unlabeled form- possible even without a H-2 coil. Because qMRS requires only standard H-1 MRS acquisition methods, it can be performed using commonly implemented single voxel spectroscopy (SVS) and chemical shift imaging (CSI) sequences. In this work, we implement qMRS in semi-LASER based CSI, generating dynamic maps arising from the fitted spectra, and demonstrating the feasibility of using qMRS and qCSI to monitor dynamic metabolism in the human brain using a 7T scanner with no auxiliary hardware.

Automated summary

In this technique, called 'qMRS', the change in H-1 MRS signal is quantified after the administration of H-2-labeled glucose. The transfer of the H-2 label from glucose to downstream metabolites leads to a reduction in the corresponding H-1 MRS resonance, allowing for the indirect and direct detection of both labeled and unlabeled forms. This technique can be performed using standard MRI acquisition methods and is feasible for monitoring dynamic metabolism in the human brain.