Simultaneous correction for interscan patient motion and geometric distortions in echoplanar imaging

A method is presented for simultaneous correction of linear geometric disto rtions and interscan patient motion in echoplanar imaging (EPI), The techni que does not require the acquisition of specialized scans other than high-r esolution magnetic resonance images. The method is based on a generalized s urface-based coregistration algorithm, which accounts for a complete 3-dime nsional affine transformation, i.e., rotations, translations, scaling, and shearing, between two volumetric image data sets. Any minimally distorted h igh-resolution scan may serve as a reference data set, to which the EPI dat a set is matched. The algorithmic accuracy was assessed using simulated dat a sets with known affine distortions. The deviation of the parameters deter mined by the coregistration program from the true values typically was 1% o r less. Precise alignment of functional and anatomic information will be im portant for many future clinical applications. Magn Reson Med 42:201-205, 1 999. (C) 1999 Wiley-Liss, Inc.