Fig. 3.

2DRF excitations and SENSE plus UNFOLD filtering were tested on a GE 3T scanner by imaging a homogeneous doped water phantom. The number and width of excitation lobes are adjusted by manipulating the 2DRF subpulse modulation and excitation k-space sampling density. a) Excitation profiles obtained with a short 2DRF pulse (3.6 ms) composed of 7 subpulses. The lobe width including transition regions is 1/6 of the full FOV and the distance between central and side lobes (1/3 FOV) are multiple of desired reduce FOV (1/12 FOV). b) Excitation profile obtained with 17 subpulses (duration 8.8 ms). c) With 17 subpulses, the FOV was reduced to 1/24 of the full FOV, for a 24-fold improvement in temporal resolution. d) Aliasing onto the central lobe from regions B and D was removed by UNFOLD e) The main bulk of the signal from the side lobes (region C) was eliminated using parallel imaging, leaving only the central lobe.