title: Interventional MR imaging. Demonstration of the feasibility of the Overhauser marker enhancement (OMEN) technique.
abstract: OBJECTIVE
  The poor localization facility of interventional instruments in MR imaging has been one of the major obstacles to the popularization of interventional MR imaging. It has been suggested that the Overhauser enhancement be used to generate markers of small size and high visibility. This article studies the feasibility of a localization marker based on this method.
  
  
  METHODS
  A small Overhauser marker was constructed on the tip of a coaxial cable and comparative images were taken by a 0.23 T imager with and without electron spin irradiation.
  
  
  RESULTS
  During irradiation an enhanced signal intensity from the marker was observed. The signal from the marker also exceeded the signal from a 0.25 mmol MnCl2 reference phantom.
  
  
  CONCLUSIONS
  Its small size and high signal-to-noise ratio, together with immunity to most system nonlinearities and imaging errors, makes the Overhauser marker a promising localization method for the accurate positioning of interventional devices. The method may be applied at any field strength, and markers are visible in images obtained with any practical imaging sequence.
authors.affiliation: Department of Radiology, Helsinki University Central Hospital, Finland.
authors.forename: R P
authors.initials: RP
authors.lastname: Joensuu
authors.forename: R E
authors.initials: RE
authors.lastname: Sepponen
authors.forename: A E
authors.initials: AE
authors.lastname: Lamminen
authors.forename: C G
authors.initials: CG
authors.lastname: Standertskjöld-Nordenstam
mesh_terms: D002712:Chlorides; D004867:Equipment Design; D005240:Feasibility Studies; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D017895:Manganese Compounds; D019047:Phantoms, Imaging; D015642:Radiology, Interventional / Q000295:instrumentation / Q000379:methods*
chemical_list: D002712:Chlorides; D017895:Manganese Compounds; C025340:manganese chloride