title: A Magnetic Resonance Imaging-Conditional External Cardiac Defibrillator for Resuscitation Within the Magnetic Resonance Imaging Scanner Bore.
abstract: BACKGROUND
  Subjects undergoing cardiac arrest within a magnetic resonance imaging (MRI) scanner are currently removed from the bore and then from the MRI suite, before the delivery of cardiopulmonary resuscitation and defibrillation, potentially increasing the risk of mortality. This precludes many higher-risk (acute ischemic and acute stroke) patients from undergoing MRI and MRI-guided intervention. An MRI-conditional cardiac defibrillator should enable scanning with defibrillation pads attached and the generator ON, enabling application of defibrillation within the seconds of MRI after a cardiac event. An MRI-conditional external defibrillator may improve patient acceptance for MRI procedures.
  
  
  RESULTS
  A commercial external defibrillator was rendered 1.5 Tesla MRI-conditional by the addition of novel radiofrequency filters between the generator and commercial disposable surface pads. The radiofrequency filters reduced emission into the MRI scanner and prevented cable/surface pad heating during imaging, while preserving all the defibrillator monitoring and delivery functions. Human volunteers were imaged using high specific absorption rate sequences to validate MRI image quality and lack of heating. Swine were electrically fibrillated (n=4) and thereafter defibrillated both outside and inside the MRI bore. MRI image quality was reduced by 0.8 or 1.6 dB, with the generator in monitoring mode and operating on battery or AC power, respectively. Commercial surface pads did not create artifacts deeper than 6 mm below the skin surface. Radiofrequency heating was within US Food and Drug Administration guidelines. Defibrillation was completely successful inside and outside the MRI bore.
  
  
  CONCLUSIONS
  A prototype MRI-conditional defibrillation system successfully defibrillated in the MRI without degrading the image quality or increasing the time needed for defibrillation. It can increase patient acceptance for MRI procedures.
authors.affiliation: From the Department of Radiology, Brigham and Women's Hospital, Boston, MA (E.J.S., W.W.); Department of Radiology, Stanford University, CA (R.D.W.); and Department of Cardiology, Johns Hopkins University, Baltimore, MD (M.M.Z., M.A.G., H.A.H.). eschmidt3@partners.org.
authors.forename: Ehud J
authors.initials: EJ
authors.lastname: Schmidt
authors.affiliation: From the Department of Radiology, Brigham and Women's Hospital, Boston, MA (E.J.S., W.W.); Department of Radiology, Stanford University, CA (R.D.W.); and Department of Cardiology, Johns Hopkins University, Baltimore, MD (M.M.Z., M.A.G., H.A.H.).
authors.forename: Ronald D
authors.initials: RD
authors.lastname: Watkins
authors.affiliation: From the Department of Radiology, Brigham and Women's Hospital, Boston, MA (E.J.S., W.W.); Department of Radiology, Stanford University, CA (R.D.W.); and Department of Cardiology, Johns Hopkins University, Baltimore, MD (M.M.Z., M.A.G., H.A.H.).
authors.forename: Menekhem M
authors.initials: MM
authors.lastname: Zviman
authors.affiliation: From the Department of Radiology, Brigham and Women's Hospital, Boston, MA (E.J.S., W.W.); Department of Radiology, Stanford University, CA (R.D.W.); and Department of Cardiology, Johns Hopkins University, Baltimore, MD (M.M.Z., M.A.G., H.A.H.).
authors.forename: Michael A
authors.initials: MA
authors.lastname: Guttman
authors.affiliation: From the Department of Radiology, Brigham and Women's Hospital, Boston, MA (E.J.S., W.W.); Department of Radiology, Stanford University, CA (R.D.W.); and Department of Cardiology, Johns Hopkins University, Baltimore, MD (M.M.Z., M.A.G., H.A.H.).
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: From the Department of Radiology, Brigham and Women's Hospital, Boston, MA (E.J.S., W.W.); Department of Radiology, Stanford University, CA (R.D.W.); and Department of Cardiology, Johns Hopkins University, Baltimore, MD (M.M.Z., M.A.G., H.A.H.).
authors.forename: Henry A
authors.initials: HA
authors.lastname: Halperin
mesh_terms: D000818:Animals; D047548:Defibrillators; D004195:Disease Models, Animal; D004554:Electric Countershock / Q000295:instrumentation*; D004867:Equipment Design; D006323:Heart Arrest / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000009:adverse effects* / Q000295:instrumentation; D008422:Materials Testing; D012151:Resuscitation / Q000295:instrumentation*; D034421:Sus scrofa; D061665:Time-to-Treatment
keywords: artifacts; cardiopulmonary resuscitation; defibrillators; magnetic resonance imaging; stroke