title: Assessing the MR compatibility of dental retainer wires at 7 Tesla.
abstract: OBJECTIVE
  To determine the MR compatibility of common dental retainer wires at 7 Tesla in terms of potential RF heating and magnetic susceptibility effects.
  
  
  METHODS
  Electromagnetic simulations and experimental results were compared for dental retainer wires placed in tissue-mimicking phantoms. Simulations were then performed for a human model with wire in place. Finally, image quality was assessed for different scanning protocols and wires.
  
  
  RESULTS
  Simulations and experimental data in phantoms agreed well, with the length of the wire correlating to maximum heating in phantoms being approximately 47 mm. Even in this case, no substantial heating occurs when scanning within the specific absorption rate (SAR) guidelines for the head. Image distortions from the most ferromagnetic dental wire were not significant for any brain region.
  
  
  CONCLUSIONS
  Dental retainer wires appear to be MR compatible at 7 Tesla.
authors.affiliation: Department of Telecommunications, Delft University of Technology, Delft, The Netherlands; C.J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Joep
authors.initials: J
authors.lastname: Wezel
authors.forename: Bert Jan
authors.initials: BJ
authors.lastname: Kooij
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Webb
mesh_terms: D065638:Absorption, Radiation; D001831:Body Temperature / Q000528:radiation effects*; D001921:Brain / Q000503:physiopathology* / Q000528:radiation effects*; D000075202:Contraindications; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D008279:Magnetic Resonance Imaging; D018704:Orthodontic Retainers; D009969:Orthodontic Wires; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011846:Radio Waves / Q000009:adverse effects
keywords: 7 Tesla; MR compatibility; contraindications; dental retainer wires; magnetic susceptibility; specific absorption ratio