Exploiting Phase Encoding Capabilities of Parallel Excitation for Improved Spatial Selectivity in Inner-Volume Imaging

Johannes Thomas Schneider^1,2, Martin Haas³, Wolfgang Ruhm¹, Juergen Hennig³, Peter Ullmann¹

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.