title: 3 Tesla MRI of patients with a vagus nerve stimulator: initial experience using a T/R head coil under controlled conditions.
abstract: OBJECTIVE
  To assess safety of clinical MRI of the head in patients with implanted model 100, 102, and 103 vagus nerve stimulation (VNS) Therapy Systems (Cyberonics, Inc., Houston, TX) in 3.0 Tesla MRI (GE Healthcare, Milwaukee, WI).
  
  
  METHODS
  The distributions of the radiofrequency B(1) (+)-field produced by the clinically used transmit/receive (T/R) head coil (Advanced Imaging Research Incorporated, Cleveland, OH) and body coil were measured in a head and shoulders phantom. These measurements were supplemented by temperature measurements on the lead tips and the implantable pulse generator (IPG) of the VNS devices in a head and torso phantom with the same two coils. Clinical 3T MRI head scans were then acquired under highly controlled conditions in a series of 17 patients implanted with VNS.
  
  
  RESULTS
  Phantom studies showed only weak B(1) (+) fields at the location of the VNS IPG and leads for MRI scans using the T/R head coil. The MRI-related heating on a VNS scanned in vitro at 3T was also found to be minimal (0.4-0.8 degrees C at the leads, negligible at the IPG). The patient MRI examinations were completed successfully without any adverse incidents. No patient reported any heating, discomfort, or any other unusual sensation.
  
  
  CONCLUSIONS
  Safe clinical MRI head scanning of patients with implanted VNS is shown to be feasible on a GE Signa Excite 3T MRI system using one specific T/R head coil. These results apply to this particular MRI system configuration. Extrapolation or generalization of these results to more general or less controlled imaging situations without supporting data of safety is highly discouraged.
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA. gorny.krzysztof@mayo.edu
authors.forename: Krzysztof R
authors.initials: KR
authors.lastname: Gorny
authors.forename: Matt A
authors.initials: MA
authors.lastname: Bernstein
authors.forename: Robert E
authors.initials: RE
authors.lastname: Watson
mesh_terms: D001831:Body Temperature / Q000528:radiation effects*; D004599:Electric Stimulation Therapy / Q000295:instrumentation* / Q000379:methods; D004574:Electromagnetic Fields; D019544:Equipment Failure Analysis; D006257:Head; D006801:Humans; D008279:Magnetic Resonance Imaging; D008280:Magnetics / Q000295:instrumentation*; D010865:Pilot Projects; D014159:Transducers; D014630:Vagus Nerve