Jinmin Xu1,2, Nicolas Arango2, Congyu Liao2,3, Berkin Bilgic2,3, Zijing Zhang1,2, Lawrence L Wald2,3, Setsompop Kawin2,3, Huafeng Liu1, and Jason P Stockmann2,3
1State key Laboratory of Modern Optical Science and Engineering, Zhejiang University, Hangzhou, China, 2A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States, 3Harvard Medical School, Boston, MA, United States
1State key Laboratory of Modern Optical Science and Engineering, Zhejiang University, Hangzhou, China, 2A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States, 3Harvard Medical School, Boston, MA, United States
A new method for improving lipid suppression using high-spatial
order, rapidly-switchable B0 shim fields.
Shim currents are jointly optimized along with the lipid saturation
pulse frequency offset to increase water-lipid spectral separation and improve
saturation efficacy.
Figure 3. Simulated comparison of
three lipid suppression scenarios in the brain.
For each case, we simulate the off-resonance histogram (c) and
z-magnetization (d) for water and lipids. (e) chemical shift artifacts in brain
slices due to residual lipid are also simulated (5x fat for a better
contrast). Using
the 32-ch AC/DC shim array, LARDS performs better than simple global
homogeneity shimming because the lipid mask used for optimization is limited
only to voxels within the passband of the water excitation pulse, reducing
constraints on the solver.
Figure 4. Three simulated cases of
lipid suppression in the abdomen. The simulated off-resonance histogram,
z-magnetization and chemical shift artifacts (5x fat for a better
contrast) clearly
show the benefit of LARDS compared to conventional shimming.