title: Magnetic Resonance Imaging at 1.5 Tesla With a Cochlear Implant Magnet in Place: Image Quality and Usability.
abstract: To study the quality and usability of magnetic resonance imaging (MRI) obtained with a cochlear implant magnet in situ.
  
  
  
  Retrospective chart review.
  
  
  
  Tertiary care center.
  
  
  
  All patients who underwent brain MRI with a cochlear implant magnet in situ from 2007 to 2016.
  
  
  
  None.
  
  
  
  Grade of view of the ipsilateral internal auditory canal (IAC) and cerebellopontine angle (CPA).
  
  
  
  Inclusion criteria were met by 765 image sequences in 57 MRI brain scans. For the ipsilateral IAC, significant predictors of a grade 1 (normal) view included: absence of fat saturation algorithm (p = 0.001), nonaxial plane of imaging (p = 0.01), and contrast administration (p = 0.001). For the ipsilateral CPA, significant predictors of a grade 1 view included: absence of fat saturation algorithm (p = 0.001), high-resolution images (p = 0.001), and nonaxial plane of imaging (p = 0.001). Overall, coronal T1 high-resolution images produced the highest percentage of grade 1 views (89%). Fat saturation also caused a secondary ring-shaped distortion artifact, which impaired the view of the contralateral CPA 52.7% of the time, and the contralateral IAC 42.8% of the time. MRI scans without any usable (grade 1) sequences had fewer overall sequences (N = 4.3) than scans with at least one usable sequence (N = 7.1, p = 0.001).
  
  
  
  MRI image quality with a cochlear implant magnet in situ depends on several factors, which can be modified to maximize image quality in this unique patient population.
authors.affiliation: *Department of Otolaryngology/Head and Neck Surgery †Department of Radiology and Radiological Science, Johns Hopkins School of Medicine, Baltimore, Maryland.
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Sharon
authors.forename: Benjamin G
authors.initials: BG
authors.lastname: Northcutt
authors.forename: Nafi
authors.initials: N
authors.lastname: Aygun
authors.forename: Howard W
authors.initials: HW
authors.lastname: Francis
mesh_terms: D000328:Adult; D001921:Brain / Q000000981:diagnostic imaging*; D003054:Cochlear Implants; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D059346:Magnets; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies