A new handle on extracellular diffusion and exchange? Single and double diffusion encoded MRS in humans after MSM ingestion

Motivation: The investigation of extracellular spaces with diffusion weighted MRI andMRS is limited by the ubiquitous distribution and fast exchange of water, while endogenous metabolites are mostly intracellular. Goal(s): Investigate the diffusion characteristics of ingested MSM compared to water and endogenous metabolites. Approach: Multi b-valued single and double diffusion encoded MRS in humans at 3T. Results: MSM diffuses anisotropically, but considerably faster than intracellular metabolites, and exhibits a substantially different behavior compared to both water and metabolites. Impact: MSM provides a novel probe of extracellular spaces similar to water but with differences that could be rotted in different transmembrane exchange properties.