Nuclear Magnetic Resonance (NMR) spectroscopy of deuterium and oxygen 17, combined with the injection of enriched glucose (2H-Glc or 17O-Glc), are promising approaches to quantify cerebral glucose fluxes in vivo. Despite the low sensitivity of these nuclei, isotopic enrichment provides high specificity to the measurements. However, the absolute quantification of glucose flux requires knowledge of the blood concentration of marked glucose, classically evaluated by blood sampling, an approach incompatible in small animals.

Diffuse Reflectance Spectroscopy (DRS) is a non-invasive optical technique that involves illuminating a diffusing medium in the infrared and measuring the spectrum of the backscattered light. This spectrum depends on the absorption and scattering properties of the medium, related to the concentration and optical characteristics of the chromophores present. Spectral analysis of the signal allows the concentration of chemical species to be determined.

To achieve absolute knowledge of glucose flux, we propose to combine NMR spectroscopy with a second modality, known as spectroscopy in a diffusing medium.