title: In vitro investigation of prosthetic heart valves in magnetic resonance imaging: evaluation of potential hazards.
abstract: OBJECTIVE
  Magnetic resonance (MR) imaging is used in an increasing number of patients, and not only after cardiac valve replacement. However, ferromagnetic biomedical implants are often considered a contraindication for MR imaging because of the potential hazards with respect to their movement, dislodgement, or heating effects during the procedure. The purpose of this study was to assess ferromagnetism, attraction forces, heating effects, and artifacts associated with prosthetic heart valve implants.
  
  
  METHODS
  Seventeen common heart valve prostheses (12 mechanical, five biological) were examined in vitro using a high-field-strength 1.5 Tesla (T) MR system. Attractive forces, temperature changes and the amount of artifacts were assessed by applying turbo-spin and gradient-echo sequences.
  
  
  RESULTS
  The maximal calculated corresponding ferromagnetic force was (0.22 x 10(-3) N) in the static magnetic field. The temperature changes ranged from 0 to 0.5 degrees C maximum. Artifacts produced by the presence of the heart valve prostheses were less evident using a spin-echo sequence than a gradient-echo sequence.
  
  
  CONCLUSIONS
  MR imaging exerted no significant force on the examined heart valve prostheses, and did not result in significant biological relevant temperature increase. None of the associated artifacts is considered to pose a substantial risk on MR imaging. MR procedures performed with a 1.5 T MR system can be applied safely in patients with heart valve prostheses evaluated in this study.
authors.affiliation: Department of Cardiothoracic and Vascular Surgery, Johannes Gutenberg-University, Mainz, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Pruefer
authors.forename: P
authors.initials: P
authors.lastname: Kalden
authors.forename: W
authors.initials: W
authors.lastname: Schreiber
authors.forename: M
authors.initials: M
authors.lastname: Dahm
authors.forename: M
authors.initials: M
authors.lastname: Buerke
authors.forename: M
authors.initials: M
authors.lastname: Thelen
authors.forename: H
authors.initials: H
authors.lastname: Oelert
mesh_terms: D016477:Artifacts; D001705:Bioprosthesis; D005290:Ferric Compounds; D006349:Heart Valve Diseases / Q000473:pathology* / Q000601:surgery*; D006350:Heart Valve Prosthesis; D006358:Hot Temperature; D066298:In Vitro Techniques; D008279:Magnetic Resonance Imaging; D008422:Materials Testing; D011474:Prosthesis Design; D013314:Stress, Mechanical
chemical_list: D005290:Ferric Compounds; C001215:ferrite