Saturation Recovery Sequence

The saturation recovery (SR) sequences are rarely used for imaging now. Their primary use at this time is as a technique to measure T1 times more quickly than an inversion recovery pulse sequence. Saturation recovery sequences consist of multiple 90 degree RF pulses at relatively short repetition times (TR). An example of a SR sequence is shown below. Residual longitudinal magnetization after the first 90 degree RF pulse is dephased by a spoiling gradient (in this case with the slice select gradient). Longitudinal magnetization that develops during the TR period after the dephasing gradient is rotated into the transverse plane by another 90 degree pulse. A gradient echo is acquired immediately after this. The signal will reflect T1 differences in tissues because of different amounts of longitudinal recovery during the TR period.