title: A 1.5T MRI-conditional 12-lead electrocardiogram for MRI and intra-MR intervention.
abstract: OBJECTIVE
  High-fidelity 12-lead electrocardiogram (ECG) is important for physiological monitoring of patients during MR-guided intervention and cardiac MRI. Issues in obtaining noncorrupted ECGs inside MRI include a superimposed magneto-hydro-dynamic voltage, gradient switching-induced voltages, and radiofrequency heating. These problems increase with magnetic field. The aim of this study is to develop and clinically validate a 1.5T MRI-conditional 12-lead ECG system.
  
  
  METHODS
  The system was constructed with transmission lines to reduce radiofrequency induction and switching circuits to remove induced voltages. Adaptive filters, trained by 12-lead measurements outside MRI and in two orientations inside MRI, were used to remove the magneto-hydro-dynamic voltage. The system was tested on 10 (one exercising) volunteers and four arrhythmia patients.
  
  
  RESULTS
  Switching circuits removed most imaging-induced voltages (residual noise <3% of the R-wave). Magneto-hydro-dynamic voltage removal provided intra-MRI ECGs that varied by <3.8% from those outside the MRI, preserving the true S-wave to T-wave segment. In premature ventricular contraction (PVC) patients, clean ECGs separated premature ventricular contraction and sinus rhythm beats. Measured heating was <1.5°C. The system reliably acquired multiphase (steady-state free precession) wall-motion-cine and phase-contrast-cine scans, including subjects in whom 4-lead gating failed. The system required a minimum repetition time of 4 ms to allow robust ECG processing.
  
  
  CONCLUSIONS
  High-fidelity intra-MRI 12-lead ECG is possible.
authors.affiliation: The University of Georgia, College of Engineering, Driftmier Engineering Center, 597 D. W. Brook Drive, Athens, GA 30602, USA.
authors.forename: Zion Tsz Ho
authors.initials: ZT
authors.lastname: Tse
authors.forename: Charles L
authors.initials: CL
authors.lastname: Dumoulin
authors.forename: Gari D
authors.initials: GD
authors.lastname: Clifford
authors.forename: Jeff
authors.initials: J
authors.lastname: Schweitzer
authors.forename: Lei
authors.initials: L
authors.lastname: Qin
authors.forename: Julien
authors.initials: J
authors.lastname: Oster
authors.forename: Michael
authors.initials: M
authors.lastname: Jerosch-Herold
authors.forename: Raymond Y
authors.initials: RY
authors.lastname: Kwong
authors.forename: Gregory
authors.initials: G
authors.lastname: Michaud
authors.forename: William G
authors.initials: WG
authors.lastname: Stevenson
authors.forename: Ehud J
authors.initials: EJ
authors.lastname: Schmidt
mesh_terms: D000368:Aged; D000818:Animals; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000601:surgery*; D055424:Cardiac-Gated Imaging Techniques / Q000295:instrumentation*; D013504:Cardiovascular Surgical Procedures / Q000295:instrumentation; D004562:Electrocardiography / Q000295:instrumentation*; D004566:Electrodes; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005260:Female; D006801:Humans; D053783:Magnetic Resonance Imaging, Interventional / Q000295:instrumentation*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D025321:Surgery, Computer-Assisted / Q000295:instrumentation*; D013552:Swine; D016896:Treatment Outcome