Critical examination of Fe8 as a contrast agent for magnetic resonance imaging

Steven Isaacman, Rajeev Kumar, Enrique Del Barco, Andrew D. Kent, James W. Canary, Alexej Jerschow

Research output: Contribution to journalArticlepeer-review


The compound Fe8 (C36H120O 23N18Fe8Br8) was examined for its potential as a contrast agent for magnetic resonance imaging. The compound was prepared, isolated, and shown to exhibit superparamagnetism (S = 10). The structure of Fe8 in aqueous solution was probed by several NMR techniques. Relaxivity of aqueous solutions of Fe8 as well as that of comparison compounds FeCl3, FeCl3(tacn) (tacn = 1,4,7-triazacyclononane), and Gd(DTPA) (DTPA = diethylenetriamine pentaacetic acid) were determined by T1 and T2 inversion recovery and CPMG sequences. In contrast to a previous report, the relaxivity of Fe 8 solutions was found to be weak compared to Gd(DTPA). However, an interesting dependence upon pH was observed. The influence of environmental factors on relaxivity is of interest in the burgeoning field of molecular imaging.

Original languageEnglish (US)
Pages (from-to)2691-2694
Number of pages4
Issue number16-17
StatePublished - Nov 17 2005


  • Contrast agent
  • Magnetic resonance imaging
  • Relaxation
  • Single-molecule magnet
  • Superparamagnet

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry


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