Cardiac phase-specific shimming (CPSS) for SSFP MR cine imaging at 3 T

The application of steady-state-free-precession (SSFP) techniques at 3 T systems is still limited by their sensitivity to magnetic field inhomogeneities. Especially during imaging of the heart, the arising signal voids and distortions in the myocardium currently often limit the diagnostic value of the resulting images. Dedicated shim systems providing higher order shimming capabilities have been applied to improve the field homogeneity across the heart. In this study, the potential benefit of applying a cardiac phase-specific shim (CPSS) was investigated. The cardiac phase dependence of the magnetic field distortions over the heart was assessed and the potential gain in field homogeneity by CPSS was evaluated. CPSS was successfully applied in volunteers and yielded significant improvement in the main magnetic field homogeneity over the entire cardiac cycle.