title: Detailing the use of magnetohydrodynamic effects for synchronization of MRI with the cardiac cycle: a feasibility study.
abstract: OBJECTIVE
  To investigate the feasibility of using magnetohydrodynamic (MHD) effects for synchronization of magnetic resonance imaging (MRI) with the cardiac cycle.
  
  
  METHODS
  The MHD effect was scrutinized using a pulsatile flow phantom at B(0) = 7.0 T. MHD effects were examined in vivo in healthy volunteers (n = 10) for B(0) ranging from 0.05-7.0 T. Noncontrast-enhanced MR angiography (MRA) of the carotids was performed using a gated steady-state free-precession (SSFP) imaging technique in conjunction with electrocardiogram (ECG) and MHD synchronization.
  
  
  RESULTS
  The MHD potential correlates with flow velocities derived from phase contrast MRI. MHD voltages depend on the orientation between B(0) and the flow of a conductive fluid. An increase in the interelectrode spacing along the flow increases the MHD potential. In vivo measurement of the MHD effect provides peak voltages of 1.5 mV for surface areas close to the common carotid artery at B(0) = 7.0 T. Synchronization of MRI with the cardiac cycle using MHD triggering is feasible. MHD triggered MRA of the carotids at 3.0 T showed an overall image quality and richness of anatomic detail, which is comparable to ECG-triggered MRAs.
  
  
  CONCLUSIONS
  This feasibility study demonstrates the use of MHD effects for synchronization of MR acquisitions with the cardiac cycle.
authors.affiliation: Berlin Ultrahigh Field Facility (B.U.F.F.), Max-Delbrueck Center for Molecular Medicine, Berlin, Germany. thoralf.niendorf@mdc-berlin.de
authors.forename: Tobias
authors.initials: T
authors.lastname: Frauenrath
authors.forename: Katharina
authors.initials: K
authors.lastname: Fuchs
authors.forename: Matthias A
authors.initials: MA
authors.lastname: Dieringer
authors.forename: Celal
authors.initials: C
authors.lastname: Özerdem
authors.forename: Nishant
authors.initials: N
authors.lastname: Patel
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Renz
authors.forename: Andreas
authors.initials: A
authors.lastname: Greiser
authors.forename: Thomas
authors.initials: T
authors.lastname: Elgeti
authors.forename: Thoralf
authors.initials: T
authors.lastname: Niendorf
mesh_terms: D055424:Cardiac-Gated Imaging Techniques / Q000379:methods*; D004562:Electrocardiography / Q000379:methods*; D005240:Feasibility Studies; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D053798:Magnetocardiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult