Open Access

As ultrahigh field cardiac MRI becomes more widespread in the (pre)clinical research arena the propensity of ECG recordings to interference from electromagnetic fields and magneto-hydrodynamic effects increases and with it the motivation for a practical gating/triggering alternative. This study compares the feasibility, efficacy and reliability phonocardiogram (ACT), vector electrocardiogram (VCG) and traditional pulse oximetry (pO2) triggered MRI for left ventricular function assessment at 7.0T. ACTs intrinsic insensitivity to interference from electro-magnetic fields and magneto-hydrodynamic effects results in an excellent trigger reliability and renders it suitable for global cardiac function assessment at ultrahigh magnetic field strengths.

Objectives Interest in cardiovascular magnetic resonance (CMR) at 7 T is motivated by the expected increase in spatial and temporal resolution, but the method is technically challenging. We examined the feasibility of cardiac chamber quantification at 7 T. Methods A stack of short axes covering the left ventricle was obtained in nine healthy male volunteers. At 1.5 T, steady-state free precession (SSFP) and fast gradient echo (FGRE) cine imaging with 7 mm slice thickness (STH) were used. At 7 T, FGRE with 7 mm and 4 mm STH were applied. End-diastolic volume, end-systolic volume, ejection fraction and mass were calculated. Results All 7 T examinations provided excellent blood/myocardium contrast for all slice directions. No significant difference was found regarding ejection fraction and cardiac volumes between SSFP at 1.5 T and FGRE at 7 T, while volumes obtained from FGRE at 1.5 T were underestimated. Cardiac mass derived from FGRE at 1.5 and 7 T was larger than obtained from SSFP at 1.5 T. Agreement of volumes and mass between SSFP at 1.5 T and FGRE improved for FGRE at 7 T when combined with an STH reduction to 4 mm. Conclusions This pilot study demonstrates that cardiac chamber quantification at 7 T using FGRE is feasible and agrees closely with SSFP at 1.5 T.