Motion correction in fMRI via registration of individual slices into an anatomical volume

An automated retrospective image registration based on mutual information i s adapted to a multislice functional magnetic resonance imaging (fMRI) acqu isition protocol to provide accurate motion correction. Motion correction i s performed by mapping each slice to an anatomic volume data set acquired i n the same fMRI session to accommodate inter-slice head motion. Accuracy of the registration parameters was assessed by registration of simulated MR d ata of the known truth. The widely used rigid body volume registration appr oach based on stacked slices from the time series data may hinder statistic al accuracy by introducing inaccurate assumptions of no motion between slic es for multislice fMRI data. Improved sensitivity and specificity of the fM RI signal from mapping-each-slice-to-volume method is demonstrated in compa rison with a stacked-slice correction method by examining functional data f rom two normal volunteers. The data presented in a standard anatomical coor dinate system suggest the reliability of the mapping-each-slice-to-volume m ethod to detect the activation signals consistent between the two subjects. Magn Reson Med 41:964-972, 1999. (C) 1999 Wiley-Liss, Inc.