TurboFLASH, FSPGR, TFE

30 TurboFLASH, FSPGR, TFE

TurboFLASH is a special, ultrafast spoiled gradient echo technique with very short TR, TE, and small excitation flip angle (note the comments at the end of this case, in respect to the definition of TR). A major consequence of the short TR and the small flip angle is that this type of sequence, in principle, has low SNR and poor T1 contrast. However, image quality can be markedly improved by using a magnetization preparation pulse, commonly a 180° inversion pulse once at the beginning of the acquisition (instead of prior to every acquisition of each Fourier line, which would imply a very long measurement time), as illustrated in Fig. 30.1. A different approach to magnetization preparation would be the use of a saturation recovery (SR) pulse, specifically a 90° RF pulse, saturating all tissues prior to the start of the imaging sequence. The preparation pulse and the short sequence parameters allow one to center the subsequent ultrafast gradient echo data acquisition at an inversion time TI, chosen to null signal from a selected tissue.

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