foerfarande foer gestaltning av kaernmagnetisk resonans som effect paoverkas av t2 * - effekter i that heterogent statiskt magnetfaelt

摘要

The T2* effects due to inherent inhomogeneities in the static magnetic field are overcome by the use of a 180 DEG RF pulse to produce a nuclear spin echo suitable for obtaining spatial information and by the adjustment of the pulsed gradients such that the occurrence of the spin echo due to the applied gradients coincides with the occurrence of the nuclear spin echo derived from the rephasing of spins in the presence of the inhomogeneities inherent in the main static magnetic field. The 180 DEG RF pulse is applied with the imaging gradients turned off so that long RF pulse lengths can be used, thus reducing RF power requirements. Exemplary applications of the pulse method to multiple angle projection reconstruction and two-dimensional Fourier transform (spin warp imaging) imaging techniques are also described.