title: Clinical utility and safety of a protocol for noncardiac and cardiac magnetic resonance imaging of patients with permanent pacemakers and implantable-cardioverter defibrillators at 1.5 tesla.
abstract: BACKGROUND
  Magnetic resonance imaging (MRI) is an important diagnostic modality currently unavailable for millions of patients because of the presence of implantable cardiac devices. We sought to evaluate the diagnostic utility and safety of noncardiac and cardiac MRI at 1.5T using a protocol that incorporates device selection and programming and limits the estimated specific absorption rate of MRI sequences.
  
  
  RESULTS
  Patients with no imaging alternative and with devices shown to be MRI safe by in vitro phantom and in vivo animal testing were enrolled. Of 55 patients who underwent 68 MRI studies, 31 had a pacemaker, and 24 had an implantable defibrillator. Pacing mode was changed to "asynchronous" for pacemaker-dependent patients and to "demand" for others. Magnet response and tachyarrhythmia functions were disabled. Blood pressure, ECG, oximetry, and symptoms were monitored. Efforts were made to limit the system-estimated whole-body average specific absorption rate to 2.0 W/kg (successful in >99% of sequences) while maintaining the diagnostic capability of MRI. No episodes of inappropriate inhibition or activation of pacing were observed. There were no significant differences between baseline and immediate or long-term (median 99 days after MRI) sensing amplitudes, lead impedances, or pacing thresholds. Diagnostic questions were answered in 100% of nonthoracic and 93% of thoracic studies. Clinical findings included diagnosis of vascular abnormalities (9 patients), diagnosis or staging of malignancy (9 patients), and assessment of cardiac viability (13 patients).
  
  
  CONCLUSIONS
  Given appropriate precautions, noncardiac and cardiac MRI can potentially be safely performed in patients with selected implantable pacemaker and defibrillator systems.
authors.affiliation: Department of Cardiology, Johns Hopkins Hospital, Carnegie 568, 600 N Wolfe St, Baltimore, MD 21287, USA. snazari1@jhmi.edu
authors.forename: Saman
authors.initials: S
authors.lastname: Nazarian
authors.forename: Ariel
authors.initials: A
authors.lastname: Roguin
authors.forename: Menekhem M
authors.initials: MM
authors.lastname: Zviman
authors.forename: Albert C
authors.initials: AC
authors.lastname: Lardo
authors.forename: Timm L
authors.initials: TL
authors.lastname: Dickfeld
authors.forename: Hugh
authors.initials: H
authors.lastname: Calkins
authors.forename: Robert G
authors.initials: RG
authors.lastname: Weiss
authors.forename: Ronald D
authors.initials: RD
authors.lastname: Berger
authors.forename: David A
authors.initials: DA
authors.lastname: Bluemke
authors.forename: Henry R
authors.initials: HR
authors.lastname: Halperin
mesh_terms: D016477:Artifacts; D002318:Cardiovascular Diseases / Q000175:diagnosis* / Q000473:pathology; D000075202:Contraindications; D017147:Defibrillators, Implantable; D004562:Electrocardiography; D004869:Equipment Safety / Q000639:trends; D006321:Heart / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000009:adverse effects*; D009206:Myocardium / Q000473:pathology; D009369:Neoplasms / Q000175:diagnosis / Q000473:pathology; D010138:Pacemaker, Artificial; D012307:Risk Factors; D014481:United States; D014486:United States Food and Drug Administration