Figure 4:

Real-time dynamic xyz-shimming sequence showing one line of k-space. Gradients (in red) along x, y and z are played out during the pulse sequence to correct for through-slice and in-plane inhomogeneities. The amplitude of these gradients is modulated in real-time by the respiratory pressure trace. Note that the pressure reading was purposely made faster for illustration purposes (one TR is much shorter than one breathing cycle).