Diffusion-Weighted Magnetic Resonance Spectroscopy

Diffusion-weighted magnetic resonance spectroscopy (DW-MRS) is a unique tool for the noninvasive exploration of the structure and physiology of the intracellular space in vivo. The method combines sensitization to diffusion using magnetic field gradients with a variety of localized MRS sequences, and thus provides the means to measure and quantify the diffusion properties of intracellular metabolites in various tissues, most commonly in the brain and in skeletal muscle. As several metabolites are preferentially found in different cell types, an investigation of the intracellular space using DW-MRS also provides cell- specific information. Information obtained from DW-MRS experiments is relevant to the assessment of the fundamental properties of the intracellular space, contributes to the understanding of diffusion-weighted MRimaging (DWI), and provides valuable information for the characterization of different pathological mechanisms in several diseases. DW-MRS measurements are extremely challenging, both from the acquisition perspective as well as from the analysis and quantification standpoint. In this article, we will present the background and motivation for performing DW-MRS studies, the various methods that have been developed thus far for the robust acquisition and analysis of DW-MRS data, and survey the variety of applications in which DW-MRS has been used to date. Keywords: diffusion, metabolites, intracellular space, tissue microstructure, brain, skeletal muscle, H-1 magnetic resonance spectroscopy, P-31 magnetic resonance spectroscopy