title: Quantitative determination of magnetic force on a coronary stent in MRI.
abstract: OBJECTIVE
  To introduce an analytical method for a quantitative determination of magnetic force on a coronary stent in the magnetic resonance imaging (MRI) magnet that is generally applicable to metallic implants. Magnetic forces on metallic implants in the MRI magnets are traditionally determined empirically by measuring deflection from the vertical plane at the central axis of the magnet and at the point of the largest force along the longitudinal axis of the magnet.
  
  
  METHODS
  Magnetic and chemical characterization of the stents was performed by a commercial magnetometer and energy-dispersive X-ray spectroscopy. Magnetic force on the stents fabricated of paramagnetic alloys (surgical stainless steel and cobalt-chromium) was determined by measuring the stent's magnetic dipole moment and employing the on-axis magnetic field profile of an MRI magnet.
  
  
  RESULTS
  The maximum force on the stainless steel stent was found to be F(S,max) = 0.18 mN, whereas on the cobalt-chromium stent it was F(C,max) = 0.06 mN.
  
  
  CONCLUSIONS
  The magnetic force on the investigated paramagnetic stents is even smaller than the gravitational force acting on the stents in the Earth's gravity field, so that it has no physiological impact on the stented vessels.
authors.affiliation: J. Stefan Institute & University of Ljubljana, Faculty of Mathematics and Physics, Ljubljana, Slovenia.
authors.forename: Nina
authors.initials: N
authors.lastname: Lopič
authors.forename: Andreja
authors.initials: A
authors.lastname: Jelen
authors.forename: Stanislav
authors.initials: S
authors.lastname: Vrtnik
authors.forename: Zvonko
authors.initials: Z
authors.lastname: Jagličić
authors.forename: Magdalena
authors.initials: M
authors.lastname: Wencka
authors.forename: Radovan
authors.initials: R
authors.lastname: Starc
authors.forename: Aleš
authors.initials: A
authors.lastname: Blinc
authors.forename: Janez
authors.initials: J
authors.lastname: Dolinšek
mesh_terms: D001807:Blood Vessel Prosthesis; D003198:Computer Simulation; D003331:Coronary Vessels / Q000601:surgery*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D060526:Magnetic Fields; D008279:Magnetic Resonance Imaging; D008962:Models, Theoretical; D015607:Stents; D013314:Stress, Mechanical