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Fast SSFP gradient echo sequence for simultaneous acquisitions of FID and echo signals
Author(s) -
Lee S. Y.,
Cho Z. H.
Publication year - 1988
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.1910080204
Subject(s) - steady state free precession imaging , flip angle , signal (programming language) , nuclear magnetic resonance , spin echo , echo (communications protocol) , pulse sequence , residual , relaxation (psychology) , physics , phase (matter) , gradient echo , echo time , chemistry , magnetic resonance imaging , algorithm , computer science , medicine , psychology , computer network , social psychology , quantum mechanics , radiology , programming language
Abstract Recently, the gradient echo imaging sequence in conjunction with small flip angle excitations and short repetition times has been widely used for fast NMR imaging. As the repetition time decreases to an extent comparable to the spin‐spin relaxation time T2, the residual phase coherency of the transverse spin magnetization tends to form another nuclear signal which is heavily weighted by T2 and similar to a long TR/long TE spin‐echo signal. This effect, although expected, has not been utilized in the conventional fast gradient echo imaging. When this residual phase coherency is utilized in conjunction with the fast SSFT ( s teady‐state f ree p recession) technique, both the FID and the echo signals can be obtained. In this paper, we have proposed a new technique by which simultaneous acquisitions of both the H D and the echo signals are possible. Experiments on this fast SSFP mode imaging have shown that the FTD signal is TI‐weighted while the echo signal is strongly T2‐weighted. The flip angle optimal for maximizing signal and related contrast are also studied in conjunction with the proposed sequence and the experimental results are presented. © 1988 Academic Press, Inc.