Johannes Thomas Schneider1,2,
Martin Haas3, Wolfgang Ruhm1, Juergen Hennig3,
Peter Ullmann1
1Bruker BioSpin
MRI GmbH, Ettlingen, Germany; 2Dept. of Radiology, Medical Physics,
University Medical Center Freiburg , Freiburg, Germany; 3Dept. of
Radiology, Medical Physics, University Medical Center Freiburg, Freiburg,
Germany
In spatially-selective excitation (SSE) experiments with short repetition times, undesired transverse magnetization outside of specified target volumes, despite being excited with small tip-angles, may be strongly pronounced compared to magnetization generated with larger tip-angles inside the target volumes because of saturation effects and different steady states. This work proposes to apply phase modulation instead of amplitude modulation in SSE, i.e. global excitation with a homogenous tip-angle distribution while achieving spatial selectivity by generating excitation phases, which differ inside and outside the target volumes according to a certain encoding scheme. This approach yields improved selectivity and significant artifact reduction.
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