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Bi-exponential 23 Na T2 * component analysis in the human brain.

Frank Riemer1,2, Bhavana S Solanky1, Claudia A M Wheeler-Kingshott1

  • 1Queen Square MS Centre, NMR Research Unit, Department of Neuroinflammation, UCL Institute of Neurology, London, UK.

NMR in Biomedicine
|February 27, 2018
PubMed
Summary

This study measured sodium (23Na) transverse relaxation time T2* in the healthy human brain using ultra-short echo times. Results provide the first detailed T2* values for various brain regions, aiding future neuroimaging research.

Keywords:
23NaUTEneuronon-Cartesianrelaxometrysodium

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Area of Science:

  • Magnetic Resonance Imaging
  • Neuroimaging
  • Biophysics

Background:

  • Sodium (23Na) magnetic resonance imaging (MRI) offers insights into brain physiology.
  • Quantifying sodium T2* relaxation times is crucial for understanding tissue microstructure.
  • Previous studies have limitations in accurately measuring short T2* components in the brain.

Purpose of the Study:

  • To measure sodium transverse relaxation time T2* in the healthy human brain.
  • To present the first comprehensive dataset of 23Na T2* values across various anatomical locations using ultra-short echo times.
  • To compare results obtained from bi-exponential and continuous distribution fitting models.

Main Methods:

  • Five healthy subjects underwent MRI scans with 18 echo times, including ultra-short echo times down to 0.17 ms.
  • Sodium T2* values were calculated voxel-by-voxel using both bi-exponential and continuous distribution models.
  • Region of interest-based inverse Laplace transform was employed for continuous distribution analysis.

Main Results:

  • Bi-exponential fitting yielded average T2* values of 3.4 ms (short) and 23.5 ms (long) in white matter (WM), and 3.9 ms (short) and 26.3 ms (long) in grey matter (GM).
  • Continuous distribution fits provided average T2* values of 3.1 ms (short) and 18.8 ms (long) in WM, and 2.9 ms (short) and 17.2 ms (long) in GM.
  • This study presents the first reported 23Na T2* values for short and long components in diverse brain regions using ultra-short echo times.

Conclusions:

  • The study successfully measured and characterized sodium T2* in the healthy human brain using advanced MRI techniques.
  • The findings provide essential reference data for sodium T2* values in different brain tissues.
  • These results pave the way for improved sodium MRI applications in neurological research and diagnostics.