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Frequency‐modulated radiofrequency pulses in spin‐echo and stimulated‐echo experiments
Author(s) -
Kunz Dietmar
Publication year - 1987
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.1910040205
Subject(s) - echo (communications protocol) , nuclear magnetic resonance , spin echo , physics , materials science , magnetic resonance imaging , medicine , computer science , radiology , computer network
Frequency‐modulated of pulses based on a linear frequency sweep are studied experimentally in spin‐echo and stimulated‐echo sequences. It turns out that these FM pulses generate a quadratic phase perpendicular to the selected slice and that the quadratic phases of the FM pulses in a spin‐echo or stimulated‐echo sequence may compensate each other if sweep velocity and gradients are suitably chosen. For a complete rephasing, a formula is given and supported by measured slice profiles. Slice profiles of excellent rectangularity are obtained. Finally, it is shown that with this technique images can be obtained using pulses of increased bandwidth and reduced peak power compared with the AM situation. © 1987 Academic Press, Inc.