Multiband spectral-spatial RF excitation for hyperpolarized [2- 13 C]dihydroxyacetone 13 C-MR metabolism studies

Magn Reson Med. 2017 Apr;77(4):1419-1428. doi: 10.1002/mrm.26226. Epub 2016 Mar 28.

Abstract

Purpose: To develop a specialized multislice, single-acquisition approach to detect the metabolites of hyperpolarized (HP) [2-13 C]dihydroxyacetone (DHAc) to probe gluconeogenesis in vivo, which have a broad 144 ppm spectral range (∼4.6 kHz at 3T). A novel multiband radio-frequency (RF) excitation pulse was designed for independent flip angle control over five to six spectral-spatial (SPSP) excitation bands, each corrected for chemical shift misregistration effects.

Methods: Specialized multiband SPSP RF pulses were designed, tested, and applied to investigate HP [2-13 C]DHAc metabolism in kidney and liver of fasted rats with dynamic 13 C-MR spectroscopy and an optimal flip angle scheme. For comparison, experiments were also performed with narrow-band slice-selective RF pulses and a sequential change of the frequency offset to cover the five frequency bands of interest.

Results: The SPSP pulses provided a controllable spectral profile free of baseline distortion with improved signal to noise of the metabolite peaks, allowing for quantification of the metabolic products. We observed organ-specific differences in DHAc metabolism. There was two to five times more [2-13 C]phosphoenolpyruvate and about 19 times more [2-13 C]glycerol 3-phosphate in the liver than in the kidney.

Conclusion: A multiband SPSP RF pulse covering a spectral range over 144 ppm enabled in vivo characterization of HP [2-13 C]DHAc metabolism in rat liver and kidney. Magn Reson Med 77:1419-1428, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Keywords: dihydroxyacetone; dynamic nuclear polarization; hyperpolarization; kidney; liver; metabolic imaging; multiband RF pulses; spectral-spatial RF pulses.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Carbon-13 Magnetic Resonance Spectroscopy / methods*
  • Dihydroxyacetone / metabolism*
  • Gluconeogenesis / physiology
  • Glucose / biosynthesis*
  • Kidney / metabolism*
  • Liver / metabolism*
  • Rats
  • Rats, Sprague-Dawley
  • Reproducibility of Results
  • Sensitivity and Specificity
  • Signal Processing, Computer-Assisted*

Substances

  • Glucose
  • Dihydroxyacetone