Sensitivity Encoding of Chemical Shifts

INTRODUCTION The chemical shift artifact (CSA) results from temporally undersampling a spatial-spectral distribution along a tilted k-t trajectory. This is illustrated in Fig. 1 for the case of H imaging. Figure 1(a) shows a typical H spatial-spectral distribution, in which the two predominant spectral components are from lipid and water protons. Figure 1(b) shows the k-t space sampling pattern typical of a spin-echo echo-planar imaging (SE-EPI) sequence. The CSA artifact (Fig. 1(c)) resulting from direct Fourier reconstruction of these samples can be understood using the projection-slice theorem.