Nonadiabatic exchange dynamics during adiabatic frequency sweeps

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

A Bloch equation analysis that includes relaxation and exchange effects during an adiabatic frequency swept pulse is presented. For a large class of sweeps, relaxation can be incorporated using simple first order perturbation theory. For anisochronous exchange, new expressions are derived for exchange augmented rotating frame relaxation. For isochronous exchange between sites with distinct relaxation rate constants outside the extreme narrowing limit, simple criteria for adiabatic exchange are derived and demonstrate that frequency sweeps commonly in use may not be adiabatic with regard to exchange unless the exchange rates are much larger than the relaxation rates. Otherwise, accurate assessment of the sensitivity to exchange dynamics will require numerical integration of the rate equations. Examples of this situation are given for experimentally relevant parameters believed to hold for in-vivo tissue. These results are of significance in the study of exchange induced contrast in magnetic resonance imaging.

Original languageEnglish (US)
Pages (from-to)45-51
Number of pages7
JournalJournal of Magnetic Resonance
Volume265
DOIs
StatePublished - Apr 1 2016

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sweep frequency
Magnetic resonance
Rate constants
Magnetic Resonance Imaging
Tissue
Imaging techniques
numerical integration
magnetic resonance
perturbation theory
sensitivity
pulses

Keywords

  • Adiabatic sweep
  • Exchange
  • Rotating frame relaxation

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Biochemistry
  • Biophysics
  • Condensed Matter Physics

Cite this

Nonadiabatic exchange dynamics during adiabatic frequency sweeps. / Barbara, Thomas.

In: Journal of Magnetic Resonance, Vol. 265, 01.04.2016, p. 45-51.

Research output: Contribution to journalArticle

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