Transverse relaxation of selectively excited metabolites in stroke at 21.1 T

Magn Reson Med. 2017 Feb;77(2):520-528. doi: 10.1002/mrm.26132. Epub 2016 Feb 1.


Purpose: This study seeks to evaluate in vivo T2 relaxation times of selectively excited stroke-relevant metabolites via 1 H relaxation-enhanced magnetic resonance spectroscopy (RE-MRS) at 21.1 T (900 MHz).

Methods: A quadrature surface coil was designed and optimized for investigations of rodents at 21.1 T. With voxel localization, a RE-MRS pulse sequence incorporating the excitation of selected metabolites was modified to include a variable echo delay for T2 measurements. A middle cerebral artery occlusion (MCAO) animal model for stroke was examined with spectra taken 24 h post occlusion. Fourteen echo times were acquired, with each measurement completed in less than 2 min.

Results: The RE-MRS approach produced high-quality spectra of the selectively excited metabolites in the stroked and contralateral regions. T2 measurements reveal differential results between these regions, with significance achieved for lactic acid.

Conclusion: Using the RE-MRS technique at ultra-high magnetic field and an optimized quadrature surface coil design, full metabolic T2 quantifications in a localized voxel is now possible in less than 27 min. Magn Reson Med 77:520-528, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Keywords: 21.1 T MRS; T2; metabolites; relaxation; stroke; ultrahigh field MRI.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Brain / metabolism*
  • Equipment Design
  • Equipment Failure Analysis
  • Lactic Acid / metabolism*
  • Male
  • Proton Magnetic Resonance Spectroscopy / instrumentation*
  • Rats
  • Rats, Sprague-Dawley
  • Reproducibility of Results
  • Sensitivity and Specificity
  • Signal Processing, Computer-Assisted / instrumentation*
  • Stroke / metabolism*
  • Transducers / veterinary*


  • Lactic Acid