Short‐TR, Spoiled, Gradient Echo Imaging

Abstract When a spin system is repeatedly disturbed by a fast repetition of RF pulses, the transverse magnetization after each new RF pulse approaches a steady‐state value which is smaller than the thermal equilibrium value. The spin system takes a finite number of pulses before this steady‐state is reached in a time that depends on both the T1 of the tissue and the flip angle of the RF pulse. Sequences utilizing a steady‐state approach can be broadly classified as steady‐state incoherent (SSI) and steady‐state coherent (SSC) sequences. The main difference between the two lies in whether the transverse magnetization is forced to zero or allowed to go naturally to steady‐state between successive RF pulses. As the nomenclature suggests, the SSI sequences are based on the elimination, or the “spoiling,” of any remnant transverse magnetization prior to the occurrence of each new RF pulse. This unit discusses the SSI sequences in detail.