Alternative sequences(3)

More possibilities:
Intermediate sequences, 
e.g., 3 lines per excitaion.

180 degree pulses does k-space reflection.
affects contrast too.
e.g., fast spin-echo.

Multi-slice imaging:
Interleaved imaging.
One slice is imaged, while others relax.
provides long TR.

Extension to 3D imaging 
3D k-space.