Figure 1

Schematic representation of the evolution of the magnetization during a 3D PSIR acquisition. The magnetization evolution is depicted of a tissue with T ₁ = 400 ms and an RR interval of 1 s. The steady state magnetization M _A, just after the inversion pulse, relaxes during the inversion delay T _inv towards M _B where the first acquisition starts with a time T _acq. The magnetization is allowed to relax again until the second acquisition at M _D. Finally the magnetization relaxes towards M _F, just before the subsequent inversion pulse. During the acquisition periods the magnetization approaches the saturated magnetization M ₀* with an effective relaxation time T ₁* (indicated by the dashed lines), depending on the repetition time TR (10 ms) and the applied flip angle α (15°). The acquisition time has a duration of n time TR where the TFE factor n = 19 in this example.