title: Assessment of MRI issues for the Argus II retinal prosthesis.
abstract: OBJECTIVE
  The objective was to evaluate magnetic resonance imaging (MRI) issues (magnetic field interactions, heating, artifacts and functional alterations) at 1.5 T and 3 T for the Argus II Retinal Prosthesis (Second Sight Medical Products, Sylmar, CA, USA).
  
  
  METHODS
  Standardized protocols were used to assess magnetic field interactions (translational attraction and torque; 3 T, worst case), MRI-related heating (1.5 and 3 T), artifacts (3 T; worst case) and functional changes (1.5 and 3 T) associated with MRI.
  
  
  RESULTS
  The magnetic field interactions were acceptable. MRI-related heating, which was studied at a relatively high, MR system-reported whole body averaged specific absorption rates, will not pose a hazard to the patient under the conditions used for testing. While artifacts were "moderate" in relation to the dimensions of the Argus II Retinal Prosthesis, optimization of MRI parameters can reduce the size of the artifacts. Exposures to MRI conditions at 1.5 and 3 T did not damage or alter the functional aspects of the Argus II Retinal Prosthesis.
  
  
  CONCLUSIONS
  In consideration of the test results, a patient with the Argus II Retinal Prosthesis may undergo MRI at 1.5 T or 3 T when specific guidelines and MRI conditions are followed, including those advised by the manufacturer.
authors.affiliation: Doheny Eye Institute, University of Southern California, Los Angeles, CA, USA.
authors.forename: James D
authors.initials: JD
authors.lastname: Weiland
authors.forename: Boozarjomehr
authors.initials: B
authors.lastname: Faraji
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Greenberg
authors.forename: Mark S
authors.initials: MS
authors.lastname: Humayun
authors.forename: Frank G
authors.initials: FG
authors.lastname: Shellock
mesh_terms: D016477:Artifacts; D004869:Equipment Safety; D006358:Hot Temperature; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D019047:Phantoms, Imaging; D018570:Risk Assessment; D019415:Torque; D057488:Visual Prosthesis