Mark Chiew1
1Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
1Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
A variable density phase encoding scheme for high-resolution EPI is shown to reduce T2* blurring and residual artefacts compared to a ¾ partial Fourier conventional EPI sampling scheme.
Figure 1 - (a) Conventional EPI phase encoding scheme showing uniform density coverage of k-space. (b) Proposed variable density EPI phase encoding, with larger PE blips at the beginning of the readout (yellow lines), and smaller blips towards the end (blue lines). (c) Conventional PE showing an exponential signal decay envelope. (d) Variable density PE with linear signal decay envelope ($$$\alpha$$$=T2*).
Figure 4 - Example reconstructions and zoomed insets. (a,d,g): Zero-filled reconstruction of the 3/4PF sampling, (b,e,h): VC reconstruction of the 3/4PF sampling, (c,f,i): VC reconstruction of the vdPE sampling. Green arrows denote a feature that is sharp in the VC reconstructions, and blurry in the zero-filled. Red arrows denote a ringing artefact visible in both 3/4PF data, but is not present in the vdPE reconstruction.
