Figure 3.
RF (A) amplitude and (B) phase waveforms for 4-ms semi-adiabatic SLR 180° RF pulse designed for shorter TE twice-refocused DWI sequence. (C) Simulated slice profile for the pulse for a range of B1 amplitudes. Because the pulse is highly truncated, there is some variation in the slice profile amplitude and shape as B1 is overdriven. A trade off exists between adiabaticity and pulse duration. Amplitude and phase waveforms for a comparative HS pulse are shown in (D) and (E). Deterioration of slice profile and loss of adiabatic behavior result from severe truncation as shown in the simulated profile in (F)