Marcus G. Ullisch1,2, Tony Stcker1, Mark A. Elliott3, Kaveh Vahedipour1, N. Jon Shah1,4
1Institute for Neurosciences and Biophysics, Research Centre Juelich, Juelich, Germany; 2Department of Psychiatry and Psychotherapy, University Hospital Aachen, Aachen, Germany; 3Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA; 4Faculty of Medicine, Department of Neurology, RWTH Aachen University, JARA, Aachen, Germany
Spherical Navigator Echoes have been used successfully as a means of estimating rotation in MRI but suffer from one shortcoming. Near the pole the slewrate of the gradient waveform increases so rapidly, that the pole caps have to be left unsampled. Thus, rotation estimation errors occur when features rotate out of the sampled area. For rotations perpendicular to the windings of the spiral a reduced accuracy compared to rotations along the windings has been reported. Here we present an alternative sampling scheme for the spherical surface which is able to sample the complete surface while staying within the slewrate limits of the hardware.
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