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Oscillating steady states
Author(s) -
Scheffler Klaus,
Maderwald Stefan,
Ladd Mark E.,
Bieri Oliver
Publication year - 2006
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.20795
Subject(s) - steady state free precession imaging , precession , amplitude , physics , signal (programming language) , nuclear magnetic resonance , pulse (music) , acoustics , optics , condensed matter physics , computer science , magnetic resonance imaging , medicine , detector , radiology , programming language
The signal formation and properties of steady‐state free precession (SSFP) in combination with alternating RF pulse phases or alternating spin precession is analyzed. Simulations and experiments demonstrate that the amplitudes of SSFP echo paths are significantly influenced by application of alternating phases either via the exciting RF pulse or via some external mechanism producing alternating spin precession. The influence of alternating phases on echo amplitudes is different for different echo paths. The primary SSFP echo paths F 0 − and F 0 + exhibit a signal reduction whereas higher‐order echoes F −1 − and F 1 + show a signal increase upon application of oscillating phases. This behavior can be described using a simple perturbation theory applied to the frequency response profile of balanced SSFP combined with a final signal integration over one balanced SSFP band. The high sensitivity of SSFP echo amplitudes to alternating RF pulse phases or precession is exemplarily used to detect and visualize propagating transverse acoustic shear waves. Detection of flow or alternating currents are further possibilities to apply this unique feature of SSFP. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.