Parallel MRI: Concepts and Methods - Advance Image Processing in Magnetic Resonance Imaging - page 74

(a) SMASH (b) AUTO−SMASH

(c) GRAPPA (d) SENSE

FIGURE 3.12 Reconstructions of uniform 2x-acceleration data using (a) SMASH, (b)
AUTO-SMASH, and (c) GRAPPA, and (d) SENSH.

for the particular case of uniform phase-encode subsampling. As seen in the
SENSE reconstruction of Figure 3.12(d), this approach successfully suppresses
almost all of the aliasing artifacts at 2x acceleration.

3.4.2 E XAMPLE 2: V ARIABLE S UBSAMPLING

As the previous example shows, successful reconstruction techniques for uniform
downsampling approaches have been developed. However, it was noted early on
that artifact suppression could be improved through nonuniform downsampling.

Figure 3.13 shows an example of the aliasing pattern that results from using a

3x-''hat” acceleration sampling pattern, and it is significantly different from the
uniform-2x aliasing pattern. Here, the hat sampling pattern follows a top-hat