Tailoring Transient Balanced Gradient Echo Coronary MRA at 3.0T
Boesiger P, Schr M, Stuber M, Kozerke S, Nezafat R
University and ETH Zurich
Balanced SSFP sequences have shown high potential for coronary MRA at 1.5T. At 3.0T, however, increased inhomogeneities of the magnetic field and the radio frequency field together with power deposition limitations cause increased off-resonance and flow related artifacts in the transient phase. This was addressed with a number of sequence changes including binomial pre-saturation followed by a Kaiser-Bessel shaped flip angle sweep to reduce transient oscillations, variable-rate selective excitation pulses to reduce repetition time, and adiabatic refocusing pulses for T2-preparation. Combined with localized shimming and resonance frequency determination excellent image quality was achieved in angiograms of the right coronary artery.