RF refocussed variable flip angle MRI using optimal pulse modulation

Comparison of the RF refocused spin echo sequence experiment with the gradient reversal refocused spin echo sequence (for partial-flip-angle magnetic resonance imaging using sinc amplitude-modulated RF waveforms) has shown that the generally observed loss in enhancement of the signal at low flip angles for the RF refocused method can be attributed to the poor slice profile of the phase reversal pulse. Using a tailored RF refocusing pulse which improves the slice profile, the expected enhancement of signal at low flip angles has been improved to a level similar to that observed with gradient reversal sequences. This technique has important applications for partial flip imaging because it allows the use of RF refocused sequences, and the elimination of the intensity distortions that have hampered the clinical application of partial-flip-angle imaging with gradient refocusing.<>