PMID: 9178245Jun 1, 1997Paper

Excitation of arbitrary shapes by gradient optimized random walk in discrete k-space

Magnetic Resonance in Medicine : Official Journal of the Society of Magnetic Resonance in Medicine
I Sersa, S Macura

Abstract

A new technique for the excitation of arbitrary shapes is proposed. It is based on a parallel sequence of small tip angle RF pulses and gradient pulses. The small tip angle rotations co-add yielding a 90 degrees excitation pulse within the selected excitation profile while outside the profile, the rotations cancel each other. A full theory of the completely arbitrary regional volume excitation (CARVE) method is presented and experimentally verified. In CARVE, k-space is discrete because the RF is applied in pulses. The discrete character of k-space permits an arbitrary trajectory for the k-space walk. The optimal random trajectory is found by minimizing the gradient load using simulated annealing. It is shown, both theoretically and experimentally, that such a trajectory is much better than any other systematic or random trajectory in k-space.

References

Aug 1, 1992·Magnetic Resonance in Medicine : Official Journal of the Society of Magnetic Resonance in Medicine·P S ChristyR L Ehman
Aug 1, 1990·Magnetic Resonance in Medicine : Official Journal of the Society of Magnetic Resonance in Medicine·C H MeyerD G Nishimura
May 1, 1996·Journal of Magnetic Resonance. Series B·I Sersa, S Macura
Apr 1, 1996·Magnetic Resonance in Medicine : Official Journal of the Society of Magnetic Resonance in Medicine·K Scheffler, J Hennig
May 13, 1983·Science·S KirkpatrickM P Vecchi

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Citations

Jan 8, 1999·Journal of Magnetic Resonance·I Sersa, S Macura
Aug 4, 2006·Physics in Medicine and Biology·Stephen F Keevil
Dec 13, 2005·Magnetic Resonance in Medicine : Official Journal of the Society of Magnetic Resonance in Medicine·Ludovic de RochefortEmmanuel Durand
Mar 18, 1999·Magnetic Resonance in Medicine : Official Journal of the Society of Magnetic Resonance in Medicine·L P Panych, K Oshio

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