Optimization of signal behavior in the transition to driven equilibrium in steady-state free precession sequences

Abstract

A new technique to avoid the initial signal fluctuations in steady-state free precession (SSFP)-sequences, such as true-FISP, FIESTA, and refocused FFE, is presented. The "transition into driven equilibrium" (TIDE) sequence uses modified flip angles over the initialization phase of a SSFP experiment, which not only avoids image artifacts but also improves the signal-tonoise ratio (SNR) and contrast behavior compared to conventional approaches. TIDE is demonstrated to be robust against variations of T1 and T2, and leads to a monotonous signal evolution for off-resonance spins. The basic principles can also be applied repetitively to optimize continuous 3D acquisitions. © 2002 Wiley-Liss, Inc.