Central Artifact Removal in Fourier NMR Imaging
Original Publication Date: 1987-Jun-01
Included in the Prior Art Database: 2005-Feb-01
Fig. 1 shows a simplified Fourier NMR imaging experiment with a single 180-degree pulse producing a spin-echo signal. A "soft" B1 pulse 1 with a slice-selecting gradient (G2) 3 excites a selected slice; a phase-encoding pulse of variable amplitude (Gy) 4. Next, a read-out gradient (Gx) with a 180-degree pulse 5 to produce a spin-echo 6 of a convenient sampling time. Other permutations of Gx, Gy and Gz may be employed to image slices in other orientations. The 180-degree pulse may be non-selective (as shown) or selective. A 180-degree pulse is required to refocus the spins and compensate for inhomogeneity of the Bo field. It also permits the sampling to be performed well away from gradient switching events.