Frequency dependence of MR relaxation times II. Iron oxides

Jeff W.M. Bulte, Josef Vymazal, Rodney A. Brooks, Carlo Pierpaoli, Joseph A. Frank

Research output: Contribution to journalArticlepeer-review

96 Scopus citations


The frequency dependence of T1 and T2 was measured for homogeneous suspensions of magnetite and iron oxyhydroxide particles in water with various concentrations of gelatin. The transverse relaxivity showed two types of behavior: (a) For magnetite particles, there was a rapid increase in T2 relaxivity with frequency, followed by a saturation plateau, which accorded with the Langevin magnetization function. From these curves, the magnetic moment of the particle domains was estimated to range from 0.8 to 6.3 104 Bohr magnetons, (b) For iron oxyhydroxide (fer‐ritin, ferrihydrite, and akaganeite) particles, T2 relaxivity increased linearly with frequency, the slope of the increase characteristic for each particle. T2 relaxivity generally increased with increasing gelatin concentration, corresponding to the measured decrease in the water diffusion coefficient. For iron oxides, homogeneously distributed either as iatrogenic agents or endogenous biominerals, these findings may aid in the interpretation of in vivo relaxivity and the effect on MR imaging.

Original languageEnglish (US)
Pages (from-to)641-648
Number of pages8
JournalJournal of Magnetic Resonance Imaging
Issue number4
StatePublished - 1993
Externally publishedYes


  • Contrast enhancement
  • Diffusion imaging
  • Iron
  • Magnetic particle imaging
  • Relaxometry

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging


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