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Frequency-modulated radiofrequency pulses in spin-echo and stimulated-echo experiments

✍ Scribed by Dietmar Kunz

Publisher
John Wiley and Sons
Year
1987
Tongue
English
Weight
369 KB
Volume
4
Category
Article
ISSN
0740-3194

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✦ Synopsis

Frequency-modulated rf 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.

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