1Tomographic Imaging, Philips Research, Hamburg, Germany, 2Oncology Solutions, Philips Research, Eindhoven, Netherlands
MR-HIFU therapies require stable
PRFS-based temperature monitoring over the treatment duration (>30min).
Drift effects may be corrected using independent temperature information e.g.
based on T2 or T1 maps and simultaneously obtained using fast interleaved
sequences. As interleaves may impact PRFS-accuracy, a dynamic on-off-interleaved
sequence pattern is introduced to selectively measure their influence on the
PRFS phase. The mechanism of the phase variations is explored using multiple
variants of the interleaved sequence. It is shown that eddy currents induced
during the interleaved sequences represent the main cause of the phase
variation. The spatio-temporal characteristics of the effect are explored as a
first step towards compensation.