4 years ago

Selective proton-observed, carbon-edited (selPOCE) MRS method for measurement of glutamate and glutamine 13C-labeling in the human frontal cortex

Douglas L. Rothman, Robin A. Graaf, Graeme F. Mason, Dennis W.J. Klomp, Bart R. Steensma, Raimund I. Herzog, Henk M. Feyter, Peter B. Brown
Purpose 13C magnetic resonance spectroscopy (MRS) in combination with infusion of 13C-labeled substrates has led to unique insights into human brain metabolism and neurotransmitter cycling. However, the low sensitivity of direct 13C MRS and high radiofrequency power requirements has limited 13C MRS studies to predominantly data acquisition in large volumes of the occipital cortex. The purpose of this study is to develop an MRS technique for localized detection of 13C-labeling of glutamate and glutamine in the human frontal lobe. Methods We used an indirect (1H-[13C]), proton-observed, carbon-edited MRS sequence (selPOCE) for detection of 13C-labeled metabolites in relatively small volumes located in the frontal lobe at 4 T. The SelPOCE method allows for selective and separate detection of glutamate and glutamine resonances, which significantly overlap at magnetic field strengths used for clinical MRI. Results Phantom data illustrate how selPOCE can be tuned to selectively detect 13C labeling in different metabolites. Three-dimensional specific absorption rate simulations of radiofrequency power deposition show that the selPOCE method operates comfortably within the global and local Food and Drug Administration specific absorption rate guidelines. In vivo selPOCE data are presented, which were acquired from a 45-mL volume in the frontal lobe of healthy subjects. The in vivo data show the time-dependent 13C-labeling of glutamate and glutamine during intravenous infusion of [1-13C]-glucose. Metrics describing spectral fitting quality of the glutamate and glutamine resonances are reported. Conclusions The SelPOCE sequence allows the detection of 13C-labeling in glutamate and glutamine from a relatively small volume in the human frontal lobe at low radiofrequency power requirements. Magn Reson Med, 2017. © 2017 International Society for Magnetic Resonance in Medicine.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/mrm.27003

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.