title: Quantification and localization of contrast agents using delta relaxation enhanced magnetic resonance at 1.5 T.
abstract: OBJECTIVE
  Delta relaxation enhanced magnetic resonance (dreMR) is a new imaging technique based on the idea of cycling the magnetic field B (0) during an imaging sequence. The method determines the field dependency of the relaxation rate (relaxation dispersion dR (1)/dB). This quantity is of particular interest in contrast agent imaging because the parameter can be used to determine contrast agent concentrations and increases the ability to localize the contrast agent.
  
  
  METHODS
  In this paper dreMR imaging was implemented on a clinical 1.5 T MR scanner combining conventional MR imaging with fast field-cycling. Two improvements to dreMR theory are presented describing the quantification of contrast agent concentrations from dreMR data and a correction for field-cycling with finite ramp times.
  
  
  RESULTS
  Experiments demonstrate the use of the extended theory and show the measurement of contrast agent concentrations with the dreMR method. A second experiment performs localization of a contrast agent with a significant improvement in comparison to conventional imaging.
  
  
  CONCLUSIONS
  dreMR imaging has been extended by a method to quantify contrast agent concentrations and improved for field-cycling with finite ramp times. Robust localization of contrast agents using dreMR imaging has been performed in a sample where conventional imaging delivers inconclusive results.
authors: Research Center for Magnetic Resonance Bavaria, Würzburg, Germany. hoelscher@mr-bavaria.de
authors: Uvo Christoph
authors: UC
authors: Hoelscher
authors: Steffen
authors: S
authors: Lother
authors: Florian
authors: F
authors: Fidler
authors: Martin
authors: M
authors: Blaimer
authors: Peter
authors: P
authors: Jakob
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D003287:Contrast Media / Q000493:pharmacokinetics; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008955:Models, Cardiovascular; D009942:Organometallic Compounds / Q000493:pharmacokinetics*; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014018:Tissue Distribution
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; C477144:gadofluorine