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. Author manuscript; available in PMC: 2015 Jun 8.
Published in final edited form as: J Magn Reson Imaging. 2012 Jul;36(1):55–72. doi: 10.1002/jmri.23639

Figure 13.

Figure 13

Examples of GRAPPA-reconstructed partitions from a 3D abdominal scan with acceleration factors of R = 4. Top left: All of the acceleration is performed in the phase-encoding direction (up-down), leading to noise enhancement (GRAPPA kernel shown in Fig. 10a). Top right: All of the acceleration is performed in the partition-encoding direction (head-foot). Because the coil array is more suited to acceleration in the up-down direction, this arrangement leads to a poorer reconstruction than when accelerating only in the phase-encoding direction. Bottom left: The acceleration has been split up between the phase and partition-encoding directions (kernel shown in Fig. 10b), thereby improving the reconstruction quality. Note the residual aliasing artifacts outside the body near the stomach and spleen. Bottom right: By using a CAIPIRINHA pattern where the acquired k-space points are offset with respect to one another (kernel shown in Fig. 10c), the g-factor is reduced and a clinically acceptable R = 4 image is generated.