Using fractional gradient information in non-rigid image registration: application to breast MRI

This work applies fractional differentiation (differentiation to non-integer order) to the gradients determined from image intensities for enhanced image registration. The technique is used to correct known simulated deformations of volumetric breast MR data using two algorithms: direct registration of gradient magnitude images and an extension of a previously published method that incorporates both image intensity and image gradient information to enhance registration performance. Better recovery of known deformations are seen when using non-integer order derivatives: half-derivative breast images are better registered when these methods are incorporated into a standard diffusion-based registration algorithm.