title: Comparison of magnetic properties of MRI contrast media solutions at different magnetic field strengths.
abstract: OBJECTIVE
  To characterize and compare commercially available contrast media (CM) for magnetic resonance imaging (MRI) in terms of their relaxivity at magnetic field strengths ranging from 0.47 T to 4.7 T at physiological temperatures in water and in plasma. Relaxivities also were quantified in whole blood at 1.5 T.
  
  
  METHODS
  Relaxivities of MRI-CM were determined by nuclear magnetic resonance (NMR) spectroscopy at 0.47 T and MRI phantom measurements at 1.5 T, 3 T, and 4.7 T, respectively. Both longitudinal (T1) and transverse relaxation times (T2) were measured by appropriate spin-echo sequences. Nuclear magnetic resonance dispersion (NMRD) profiles were also determined for all agents in water and in plasma.
  
  
  RESULTS
  Significant dependencies of relaxivities on the field strength and solvents were quantified. Protein binding leads to both increased field strength and solvent dependencies and hence to significantly altered T1 relaxivity values at higher magnetic field strengths.
  
  
  CONCLUSIONS
  Awareness of the field strength and solvent associated with relaxivity data is crucial for the comparison and evaluation of relaxivity values. Data observed at 0.47 T can thus be misleading and should be replaced by relaxivities measured at 1.5 T and at 3 T in plasma at physiological temperature.
authors.affiliation: Global Business Unit Diagnostic Imaging, Schering AG, Berlin, Germany. Martin.Rohrer@Schering.de
authors.forename: Martin
authors.initials: M
authors.lastname: Rohrer
authors.forename: Hans
authors.initials: H
authors.lastname: Bauer
authors.forename: Jan
authors.initials: J
authors.lastname: Mintorovitch
authors.forename: Martin
authors.initials: M
authors.lastname: Requardt
authors.forename: Hanns-Joachim
authors.initials: HJ
authors.lastname: Weinmann
mesh_terms: D003287:Contrast Media / Q000737:chemistry*; D005682:Gadolinium / Q000097:blood / Q000737:chemistry* / Q000378:metabolism; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008280:Magnetics; D011485:Protein Binding; D014867:Water / Q000737:chemistry
chemical_list: D003287:Contrast Media; D014867:Water; D005682:Gadolinium