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Abstract #4178

Towards the Assessment of Intracellular Viscosity: Diffusion Spectroscopy at Ultra-Short Diffusion Time in the Rat Brain

Charlotte Marchadour1, Martine Guillermier1, Diane Houitte1, Marion Chaigneau1, Philippe Hantraye1, Vincent Lebon1, Julien Valette1

1CEA-MIRCen, Fontenay-aux-Roses, France

Given the intracellular compartmentation of brain metabolites, diffusion-weighted (DW) spectroscopy is a unique tool to assess properties of the intracellular space. Long diffusion times Td are traditionally used for DW-spectroscopy, yielding apparent diffusion coefficient (ADC) that depend on restriction. In contrast, ADC measured for shorter Td would reflect free diffusion and yield an indirect estimate of intracellular viscosity. Using a modified LASER sequence incorporating oscillating gradients, we could measure ADC of NAA, creatine and choline for Td down to ~1 ms. It is shown that metabolite ADC dramatically increases as Td decreases, approaching values consistent with the free diffusion regime.