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In vivo measurement of apparent diffusion coefficients of hyperpolarized 13 C‐labeled metabolites
Author(s) -
Søgaard Lise Vejby,
Schilling Franz,
Janich Martin A.,
Menzel Marion I.,
ArdenkjærLarsen Jan Henrik
Publication year - 2014
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.3093
Subject(s) - chemistry , nuclear magnetic resonance , extracellular , metabolite , in vivo , diffusion , effective diffusion coefficient , alanine , pulse (music) , analytical chemistry (journal) , amino acid , physics , biochemistry , chromatography , magnetic resonance imaging , biology , detector , medicine , microbiology and biotechnology , radiology , optics , thermodynamics
The combination of hyperpolarized MRS with diffusion weighting (dw) allows for determination of the apparent diffusion coefficient (ADC), which is indicative of the intra‐ or extracellular localization of the metabolite. Here, a slice‐selective pulsed‐gradient spin echo sequence was implemented to acquire a series of dw spectra from rat muscle in vivo to determine the ADCs of multiple metabolites after a single injection of hyperpolarized [1‐ 13 C]pyruvate. An optimal control optimized universal‐rotation pulse was used for refocusing to minimize signal loss caused by B 1 imperfections. Non‐dw spectra were acquired interleaved with the dw spectra and these were used to correct for signal decay during the acquisition as a result of T 1 decay, pulse imperfections, flow etc. The data showed that the ADC values for [1‐ 13 C]lactate (0.4–0.7 µm 2 /ms) and [1‐ 13 C]alanine (0.4–0.9 µm 2 /ms) were about a factor of two lower than the ADC of [1‐ 13 C]pyruvate (1.1–1.5 µm 2 /ms). This indicates a more restricted diffusion space for the former two metabolites consistent with lactate and alanine being intracellular. The higher ADC for pyruvate (similar to the proton ADC) reflected that the injected substance was not confined inside the muscle cells but also present extracellular. Copyright © 2014 John Wiley & Sons, Ltd.