Image-based ghost correction for interleaved EPI

A new image-based ghost correction technique is described for general inter leaved EPI. This technique works reliably with both even- and odd-number in terleaved EPI sequences. It estimates the phase distortions causing the gho sts as a general function of tx,YI even in the presence of a significant ov erlap of parent image and ghosts. If the phase distortion is assumed to be a function of x (frequency-encode direction) only, the new technique is sim ilar to a recently published correction method for general interleaved EPI (Hennel, J Magn Reson 1998;134:206-213), However, that study concluded that the method for general interleaved EPI did not work. If showed that the SN Rs of the edge pixels were too low to accurately estimate the phase distort ion. The new technique utilizes not one, but many pixels in the image for e stimating the phase distortion. The technique requires a user-defined ROI t o outline the parent image and identify so-called eligible pixels for estim ating the phase distortion, When all eligible pixels are used, the SNR of t he phase distortion estimate is comparable to that obtained in single-shot EPI. This study provides the first examples of high-quality, image-based co rrection of multiple ghosts in general interleaved EPI, Magn Reson Med 45:9 6-108, 2001. (C) 2001 Wiley-Liss, Inc.