Figure 5. Basic pulse sequence for two-dimensional¹⁹Fluorine imaging with a slice selection scheme based on selective inversion [33]G^slice= slice-selecting gradient; G^phase= phase-encoding gradient; and G^read= frequency-encoding gradient. Images are constructed using the spectral differences with and without the 180 degrees secant-shaped selective inversion pulses. Note that the shaped pulse is not part of the TE. Therefore, the minimum echo time in this sequence is the same as that in a three-dimensional gradient-recalled echo sequence and limited only by the gradient switching time and eddy-current effects in the volume of interest.