Symmetric Block-Matching Registration for the Distortion Correction of Echo-Planar Images

Abstract : We introduce a new approach to correct geometric and in- tensity distortion of Echo Planar Images (EPI) from images acquired with opposite phase encoding directions. A new symmetric block-matching registration algorithm has been developed for this purpose relying on new adapted transfor- mations between blocks and a symmetric optimization scheme to ensure an opposite symmetric transformation. We present results of our algorithm showing its ability to robustly re- cover EPI distortion while obtaining sharper results than the popular TOPUP algorithm.