Micro-compartment specific T2* relaxation in the brain

Pascal Sati, Peter van Gelderen, Afonso C. Silva, Daniel S. Reich, Hellmut Merkle, Jacco A. De Zwart, Jeff H. Duyn

Research output: Contribution to journalArticlepeer-review

Abstract

MRI at high field can be sensitized to the magnetic properties of tissues, which introduces a signal dependence on the orientation of white matter (WM) fiber bundles relative to the magnetic field. In addition, study of the NMR relaxation properties of this signal has indicated contributions from compartmentalized water environments inside and outside the myelin sheath that may be separable. Here we further investigated the effects of water compartmentalization on the MRI signal with the goal of extracting compartment-specific information. By comparing MRI measurements of human and marmoset brain at 7. T with magnetic field modeling, we show that: (1) water between the myelin lipid bilayers, in the axonal, and in the interstitial space each experience characteristic magnetic field effects that depend on fiber orientation (2) these field effects result in characteristic relaxation properties and frequency shifts for these compartments; and (3) compartmental contributions may be separated by multi-component fitting of the MRI signal relaxation (i.e. decay) curve. We further show the potential application of these findings to the direct mapping of myelin content and assessment of WM fiber integrity with high field MRI.

Original languageEnglish (US)
Pages (from-to)268-278
Number of pages11
JournalNeuroImage
Volume77
DOIs
StatePublished - Aug 15 2013

Keywords

  • Brain
  • Demyelination
  • Frequency shift
  • T relaxation
  • Water compartment
  • White matter

ASJC Scopus subject areas

  • Neurology
  • Cognitive Neuroscience

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