Restoration of EPI Susceptibility Distortion at 3T: Comparison of Fluid-Dynamic Image Registration with Phase-Encoding Gradient Reversion
Mller H, Schfer A, Tittgemeyer M, Imperati D
Max Planck Institute for Human Cognitive and Brain Sciences, University Hospital Mnster
We propose a cross evaluation of restoration methods for EPI images. Two strategies were tested to un-distort the images: image registration of the distorted image with an undistorted (reference) image of similar contrast, and co-registration of two distorted images acquired with inverted phase-encoding. Testing included phantom experiments and in vivo imaging of human brain. Results were compared to undistorted reference images to the known phantom structure. Fluid-dynamic image registration appeared to be better than reversed-gradient methods, because it accounts for large displacements and is able to correct for distortions in slice-select gradient direction, too.