Figure 1.

Acquisition strategy and flow diagram of the 2D phase and amplitude correction algorithm. During the acquisition, additional phase encoded reference lines (N_r) are collected but with the reversed gradient polarity at each echo. Each line represents one k-space phase encoded line, and the direction of the arrows indicates the gradient polarity used. During the reconstruction, the pair of center k-space lines collected with opposite gradient polarities is used for estimating a linear dominant phase error in the read-out direction. The remaining high order phase errors are corrected using the pair of low-resolution images reconstructed from the center N_r lines. Finally, the phase corrected reference lines are combined with the regular data to form the final multi-echo data, which are then processed by the IDEAL algorithm to separate water and fat.