Avoiding artifacts in NMR fourier zeugmatography - determining nuclear magnetisation distribution by applying inhomogeneous extra magnetic field before and after second HF EM pulse

摘要

The distribution of nuclear magnetisation is determined in part of a body using a device producing a stationary, homogeneous magnetic field in which the body lies. An h.f. e.m. pulse is produced followed by a gradient magnetic field which is then followed by a second pulse. The nuclear spin echo is measured. The whole process is repeated after an interval. Before producing the second h.f. pulse an extra inhomogeneous magnetic field is applied. The second pulse is produced and then an extra inhomogeneous magnetic field is again applied so that the nuclear magnetisation acting on the nuclear spin echo signal is zero.