Figure 3:

Overview of the reconstruction process: After ghost correction, conventional slice-GRAPPA and in-plane GRAPPA are performed. Then, an additional phase matching step is used for each image. For this step, the smoothed difference between the image phase and reference image phase is found, and then added coil-by-coil back to the reference data to create matched reference data for each image. Then, virtual coils are created from the phase-matched reference and acquired data, followed by a joint slice-GRAPPA and joint in-plane GRAPPA, where the additional images used are stacked along the channel axis.