Proton diffusion tensor spectroscopy of metabolites in human muscle in vivo

Abstract

Diffusivities, directional dependence of diffusion and fractional anisotropies of (1) H MRS-visible muscle metabolites were presented. It was shown that metabolites share diffusion directionality with water and have similar fractional anisotropies, hinting at similar diffusion barriers.

Diffusion‐weighted magnetic resonance spectroscopy boosted by simultaneously acquired water reference signals

“…In that case, the sum spectra (including the motion‐corrupted scans) can be scaled such that the macromolecular peak is at a constant or expected level for each b ‐value. Such a correction scheme is similar to what had been suggested for investigations of metabolite diffusion in skeletal muscle, in which the lipid signals had been used as reference . The use of the macromolecular peak at 0.9 ppm for single shot outlier rejection has been used for animal studies but relies on much better SNR than available in our human studies.…”

“…All experiments were conducted on 3T MR scanners (Verio, Trio, or Prisma; Siemens, Erlangen, Germany) using a single proton channel transmit–receive volume coil ( 1 H/ 31 P head coil; RAPID Biomedical, Rimpar, Germany) or multichannel head coils (20 or 32 channels). Based on the Siemens product STEAM sequence, a nWS‐DWS sequence (see Figure ) was implemented . Pairs of pulsed diffusion field gradients were inserted before and after the mixing time (TM).…”

“…In this contribution, we suggest an alternative sequence design for DW‐MRS using a non–water‐suppressed DW‐MRS (nWS–DW‐MRS) sequence with metabolite‐cycling and fluid‐attenuated inversion recovery (FLAIR) CSF suppression, which allows measuring metabolite and water signals simultaneously . In addition, a novel correction scheme is introduced that allows artefact correction and motion compensation (MoCom) using the co‐acquired water signal as inherent reference and also enables compensation for nonlinear motion, rendering cardiac and respiratory gating dispensable.…”

Addressing spontaneous signal voids in repetitive single‐shot DWI of musculature: spatial and temporal patterns in the calves of healthy volunteers and consideration of unintended muscle activities as underlying mechanism

“…In addition, effects of passive shortening and stretching of musculature and exercise effects on diffusion tensor characteristics have been examined successfully. Recent IVIM studies have reported on assessment of muscular perfusion and on diffusion tensor properties of metabolites visible in volume‐localized 1 H spectra .…”

“…In addition, effects of passive shortening and stretching of musculature (21) and exercise effects (22,23) on diffusion tensor characteristics have been examined successfully. Recent IVIM studies have reported on assessment of muscular perfusion (24) and on diffusion tensor properties of metabolites visible in volume-localized 1 H spectra (25). Problems with noise (26), but also with 'data outliers' (27) and 'pulsation effects' from vasculature (28), were reported for DWI in several publications.…”