Kawin Setsompop1, 2, Lawrence L. Wald1, 3
1Dept. of Radiology, A. A. Martinos Center for Biomedical Imaging, MGH, Charlestown, MA, United States; 2Harvard Medical School, Boston, MA, United States; 3Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA, United States
Simultaneous multi-slice EPI using parallel imaging allows for an increase in sampling rate of fMRI and reduced acquisition time in diffusion imaging. Nonetheless, the unaliasing problem is difficult for closely spaced simultaneously excited slices. A blipped-CAIPI acquisition scheme was introduced to mitigate this issue by creating an inter-slice image shift to increase the distance between aliased voxels. In this work, we show that spatially varying field inhomogeneities and eddy currents can cause significant aliasing artifact in the form of inter-slice ghost leakage which is particularly problematic for blipped-CAIPI acquisitions. A multi-kernel slice-GRAPPA reconstruction technique is proposed to mitigate this issue.
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