magnetic fields for imparting gradients to the static magnet field strength the gradient magnetic fields to be generated include three types of magnetic fields a slice gradient magnetic field a readout gradient magnetic field and a phase encoding gradient magnetic field and the gradient coil section 106 u2032 has three gradient coils not shown corresponding to these three gradient magnetic fields the rf coil section 108 u2032 transmits an rf excitation signal to the static magnetic field space to excite spins within the subject to be imaged 300 the rf coil section 108 u2032 also receives a magnetic resonance signal generated by the excited spins the rf coil section 108 u2032 has a transmit coil and a receive coil not shown the transmit and receive coils may be either the same coil or separate dedicated coils fig5 shows an exemplary pulse sequence for use in magnetic resonance imaging the illustrated pulse sequence is one for a spin echo se technique specifically 1 is a sequence of 90 u00b0 and 180 u00b0 pulses for rf excitation of the se technique and 2 3 4 and 5 are sequences of a slice gradient gs a readout gradient gr a phase encoding gradient gp and a spin echo mr respectively of the se technique it should be noted that the 90 u00b0 and 180 u00b0 pulses are represented by their respective central signals the pulse sequence proceeds from the left to the right along a time axis t as.