Lactate saturation limits bicarbonate detection in hyperpolarized 13 C-pyruvate MRI of the brain

Nikolaj Bøgh*, James T. Grist, Camilla W. Rasmussen, Lotte B. Bertelsen, Esben S. S. Hansen, Jakob U. Blicher, Damian J. Tyler, Christoffer Laustsen

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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PURPOSE: To investigate the potential effects of [1-13 C]lactate RF saturation pulses on [13 C]bicarbonate detection in hyperpolarized [1-13 C]pyruvate MRI of the brain.

METHODS: Thirteen healthy rats underwent MRI with hyperpolarized [1-13 C]pyruvate of either the brain (n = 8) or the kidneys, heart, and liver (n = 5). Dynamic, metabolite-selective imaging was used in a cross-over experiment in which [1-13 C]lactate was excited with either 0° or 90° flip angles. The [13 C]bicarbonate SNR and apparent [1-13 C]pyruvate-to-[13 C]bicarbonate conversion (kPB ) were determined. Furthermore, simulations were performed to identify the SNR optimal flip-angle scheme for detection of [1-13 C]lactate and [13 C]bicarbonate.

RESULTS: In the brain, the [13 C]bicarbonate SNR was 64% higher when [1-13 C]lactate was not excited (5.8 ± 1.5 vs 3.6 ± 1.3; 1.2 to 3.3-point increase; p = 0.0027). The apparent kPB decreased 25% with [1-13 C]lactate saturation (0.0047 ± 0.0008 s-1 vs 0.0034 ± 0.0006 s-1 ; 95% confidence interval, 0.0006-0.0019 s-1 increase; p = 0.0049). These effects were not present in the kidneys, heart, or liver. Simulations suggest that the optimal [13 C]bicarbonate SNR with a TR of 1 s in the brain is obtained with [13 C]bicarbonate, [1-13 C]lactate, and [1-13 C]pyruvate flip angles of 60°, 15°, and 10°, respectively.

CONCLUSIONS: Radiofrequency saturation pulses on [1-13 C]lactate limit [13 C]bicarbonate detection in the brain specifically, which could be due to shuttling of lactate from astrocytes to neurons. Our results have important implications for experimental design in studies in which [13 C]bicarbonate detection is warranted.

Original languageEnglish
JournalMagnetic Resonance in Medicine
Issue number3
Pages (from-to)1170-1179
Number of pages10
Publication statusPublished - Sep 2022

Bibliographical note

© 2022 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals LLC on behalf of International Society for Magnetic Resonance in Medicine.


  • astrocyte neuron lactate shuttle
  • brain
  • hyperpolarized
  • magnetic resonance imaging
  • metabolism
  • pyruvate
  • Lactic Acid
  • Bicarbonates
  • Carbon Isotopes
  • Rats
  • Magnetic Resonance Imaging/methods
  • Brain/diagnostic imaging
  • Animals
  • Pyruvic Acid


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