Composite pulses for time reversal in NMR imaging

摘要

Composite pulses are employed in NMR imaging for time-reversal of nuclear spins in a transverse planar region of a sample to produce spin-echo signals. The composite pulses comprise a sequence of pulses for producing a 90 DEG rotation of the spins about a first transverse axis, a 180 DEG rotation of the spins about a substantially orthogonal transverse axis, and a 90 DEG rotation of the nuclear spins about the first transverse axis. The composite pulses minimize time-reversal errors caused by static magnetic field and RF field inhomogeneities, and afford multiple spin-echo NMR imaging sequences.