Probing cardiac metabolism by hyperpolarized 13C MR using an exclusively endogenous substrate mixture and photo-induced nonpersistent radicals

Jessica A M Bastiaansen*, Hikari A I Yoshihara, Andrea Capozzi, Juerg Schwitter, Rolf Gruetter, Matthew E Merritt, Arnaud Comment

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Abstract

To probe the cardiac metabolism of carbohydrates and short chain fatty acids simultaneously in vivo following the injection of a hyperpolarized 13 C-labeled substrate mixture prepared using photo-induced nonpersistent radicals. Droplets of mixed [1-13 C]pyruvic and [1-13 C]butyric acids were frozen into glassy beads in liquid nitrogen. Ethanol addition was investigated as a means to increase the polarization level. The beads were irradiated with ultraviolet light and the radical concentration was measured by ESR spectroscopy. Following dynamic nuclear polarization in a 7T polarizer, the beads were dissolved, and the radical-free hyperpolarized solution was rapidly transferred into an injection pump located inside a 9.4T scanner. The hyperpolarized solution was injected in healthy rats to measure cardiac metabolism in vivo. Ultraviolet irradiation created nonpersistent radicals in a mixture containing 13 C-labeled pyruvic and butyric acids, and enabled the hyperpolarization of both substrates by dynamic nuclear polarization. Ethanol addition increased the radical concentration from 16 to 26 mM. Liquid-state 13 C polarization was 3% inside the pump at the time of injection, and increased to 5% by addition of ethanol to the substrate mixture prior to ultraviolet irradiation. In the rat heart, the in vivo 13 C signals from lactate, alanine, bicarbonate, and acetylcarnitine were detected following the metabolism of the injected substrate mixture. Copolarization of two different 13 C-labeled substrates and the detection of their myocardial metabolism in vivo was achieved without using persistent radicals. The absence of radicals in the solution containing the hyperpolarized 13 C-substrates may simplify the translation to clinical use, as no radical filtration is required prior to injection.
Original languageEnglish
JournalMagnetic Resonance in Medicine
Volume79
Issue number5
Pages (from-to)2451-2459
Number of pages9
ISSN0740-3194
DOIs
Publication statusPublished - 2018

Keywords

  • Carbon-13
  • Energy metabolism
  • Hyperpolarization
  • Metabolic imaging
  • Oxidative metabolism

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