Detailing the use of magnetohydrodynamic effects for synchronization of MRI with the cardiac cycle: A feasibility study

Abstract

To investigate the feasibility of using magnetohydrodynamic (MHD) effects for synchronization of magnetic resonance imaging (MRI) with the cardiac cycle. 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. 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. This feasibility study demonstrates the use of MHD effects for synchronization of MR acquisitions with the cardiac cycle.