The CIBM had the pleasure to host a seminar on the measurement of metabolite diffusion with diffusion-weighted MR spectroscopy by Dr. Julien Valette – from the Commissariat à l’Energie Atomique (CEA) in Paris – on Friday December 13th.
Diffusion-weighted NMR spectroscopy (DW-MRS) offers the unique ability to non-invasively quantify the diffusion of endogenous metabolites in vivo. In contrast to water, which is ubiquitous in biological tissues, most metabolites are confined within cells. Their diffusion properties are thus expected to mostly depend on intracellular parameters such as cytosol viscosity, molecular crowding, size and shape of the cell… Furthermore, in the brain, some metabolites are thought to exhibit preferential compartmentation, with N-acetyl-aspartate (NAA) and glutamate (Glu) being mostly in neurons, while myo-inositol (mIns) and choline compounds (tCho) are thought to be preferentially compartmentalized in glial cells. Cellular specificity has been the main motivation driving methodological research and applications of DW-MRS in vivo over the last 25 years.
Dr. Valette first evoked some general difficulties and advantages of metabolite diffusion as compared to water diffusion. Then, he browsed through the main applications of DW-MRS to date, including the determination of lipid droplets diameter, the measurement of alterations of metabolite apparent diffusion coefficient (ADC) in brain diseases, and more recently the modeling of DW-MRS data to gain some quantitative information about brain cell microstructure. Finally, in a more technically-oriented section, Dr. Julien Valette examined how to implement DW-MRS.
Abstract & Biography : Dr. Julien Valette – Measuring metabolite diffusion with diffusion-weighted MR spectroscopy