Multiple echo SSFP sequences.
We report a new type of SSFP imaging sequences for acquiring higher-order echoes. Spins excited during a cycle have, in a sense, a phase memory such that they can be refocused several cycles down the line, and since the spins are pulsed under a steady-state condition, the resulting echoes have very complicated T1 and T2 dependencies. A steady-state equation, which describes the T1 and T2 dependencies for the higher-order echoes, is presented, and the intensity of each echo is calculated and compared with the experimental results. Although the signal intensity of the higher-order echoes are weaker than the FID or the CE-FAST echo, these echoes may be used to obtain images with different contrast dependencies previously unobtainable with either of the two signals.
Mizumoto
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Research and Development Division, Yokogawa Medical Systems, Ltd., Tokyo, Japan.
Yoshitome
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D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008961:Models, Structural