title: Impact of orthodontic appliances on the quality of craniofacial anatomical magnetic resonance imaging and real-time speech imaging.
abstract: OBJECTIVE
  The aim of this work was to investigate the effects of commonly used orthodontic appliances on the magnetic resonance (MR) image quality of the craniofacial region, with special interest in the soft palate and velopharyngeal wall using real-time speech imaging sequences and anatomical imaging of the temporomandibular joints (TMJ) and pituitaries.
  
  
  METHODS
  Common orthodontic appliances were studied on 1.5 T scanner using standard spin and gradient echo sequences (based on the American Society for Testing and Materials standard test method) and sequences previously applied for high-resolution anatomical and dynamic real-time imaging during speech. Images were evaluated for the presence and size of artefacts.
  
  
  RESULTS
  Metallic orthodontic appliances had different effects on image quality. The most extensive individual effects were associated with the presence of stainless steel archwire, particularly if combined with stainless steel brackets and stainless steel molar bands. With those appliances, diagnostic quality of magnetic resonance imaging speech and palate images will be most likely severely degraded, or speech imaging and imaging of pituitaries and TMJ will be not possible. All non-metallic, non-metallic with Ni/Cr reinforcement or Ni/Ti alloys appliances were of little concern.
  
  
  CONCLUSIONS
  The results in the study are only valid at 1.5 T and for the sequences and devices used and cannot necessarily be extrapolated to all sequences and devices. Furthermore, both geometry and size of some appliances are subject dependent, and consequently, the effects on the image quality can vary between subjects. Therefore, the results presented in this article should be treated as a guide when assessing the risks of image quality degradation rather than an absolute evaluation of possible artefacts.
  
  
  CONCLUSIONS
  Appliances manufactured from stainless steel cause extensive artefacts, which may render image non-diagnostic. The presence and type of orthodontic appliances should be always included in the patient's screening, so the risks of artefacts can be assessed prior to imaging. Although the risks to patients with fixed orthodontic appliances at 1.5 T MR scanners are low, their secure attachment should be confirmed prior to the examination.
authors: *Clinical Physics, Barts Health NHS Trust, London, **Barts and the London NIHR CVBRU, London Chest Hospital.
authors: Marzena
authors: M
authors: Wylezinska
authors: ***Cleft Lip and Palate Team, Great Ormond Street Hospital for Children, London.
authors: Marie
authors: M
authors: Pinkstone
authors: ****Dental and Maxillofacial Department, Great Ormond Street Hospital for Children, London.
authors: Norman
authors: N
authors: Hay
authors: *Clinical Physics, Barts Health NHS Trust, London, *****NIHR Cardiovascular Biomedical Research Unit, The Royal Brompton Hospital, London, UK.
authors: Andrew D
authors: AD
authors: Scott
authors: *Clinical Physics, Barts Health NHS Trust, London.
authors: Malcolm J
authors: MJ
authors: Birch
authors: *Clinical Physics, Barts Health NHS Trust, London, **Barts and the London NIHR CVBRU, London Chest Hospital, m.e.miquel@qmul.ac.uk.
authors: Marc E
authors: ME
authors: Miquel
mesh_terms: D016477:Artifacts; D002516:Ceramics / Q000737:chemistry; D002858:Chromium Alloys / Q000737:chemistry; D003722:Dental Alloys / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008422:Materials Testing; D009532:Nickel / Q000737:chemistry; D009967:Orthodontic Appliances; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D010160:Palate, Soft / Q000033:anatomy & histology / Q000502:physiology; D010614:Pharynx / Q000033:anatomy & histology / Q000502:physiology; D010902:Pituitary Gland / Q000033:anatomy & histology; D013060:Speech / Q000502:physiology*; D013193:Stainless Steel / Q000737:chemistry; D013704:Temporomandibular Joint / Q000033:anatomy & histology; D014025:Titanium / Q000737:chemistry
chemical_list: D002858:Chromium Alloys; D003722:Dental Alloys; D003764:Dental Materials; C040654:titanium nickelide; D013193:Stainless Steel; D009532:Nickel; D014025:Titanium