Protein-induced water 1H MR frequency shifts: Contributions from magnetic susceptibility and exchange effects

Jie Luo, Xiang He, D. Andre d'Avignon, Joseph J.H. Ackerman, Dmitriy A. Yablonskiy

Research output: Contribution to journalArticlepeer-review

63 Scopus citations

Abstract

Defining the biophysics underlying the remarkable MRI phase contrast reported in high field MRI studies of human brain would lead to more quantitative image analysis and more informed pulse sequence development. Toward this end, the dependence of water 1H resonance frequency on protein concentration was investigated using bovine serum albumin (BSA) as a model system. Two distinct mechanisms were found to underlie a water 1H resonance frequency shift: (i) a protein-concentration-induced change in bulk magnetic susceptibility, causing a shift to lower frequency, and (ii) exchange of water between chemical-shift distinct environments, i.e., free (bulk water) and protein-associated ("bound") water, including freely exchangeable 1H sites on proteins, causing a shift to higher frequency. At 37 °C the amplitude of the exchange effect is roughly half that of the susceptibility effect.

Original languageEnglish (US)
Pages (from-to)102-108
Number of pages7
JournalJournal of Magnetic Resonance
Volume202
Issue number1
DOIs
StatePublished - Jan 2010
Externally publishedYes

Keywords

  • 1,4-Dioxane
  • BSA
  • MRI
  • Phase imaging
  • Susceptibility contrast
  • TSP
  • Water exchange

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