A fast and robust minimum entropy based non-interactive Nyquist ghost correction algorithm
Skare S, Newbould R, Clayton D, Bammer R, Moseley M
Nyquist ghosts in EPI are normally measured by a reference scan in clinical practice. This may take over a minute for a multi-shot, multi-slice and multi-coil EPI scan. Using the EPI rawdata itself, without reference scans or user intervention, it is possible to iteratively search for the minimum entropy of the reconstructed magnitude image by altering the two first order phase correction parameters. The entropy metric is however not a smooth objective function, and may fail if ghosts are high. Here we present a sub-second safe way to find the solution of correcting the ghosts using the minimum entropy.