Simultaneous Correction of Intensity Inhomogeneity in Multi-Channel MR Images.

Intensity inhomogeneity in MR images is an undesired phenomenon, which often hampers different steps of quantitative analysis such as segmentation or registration. In this paper we propose a novel fully automated method for retrospective correction of intensity inhomogeneity. The basic assumption is that inhomogeneity correction could be improved by combining the information from multiple MR channels. Intensity inhomogeneities are simultaneously removed in a four-step iterative procedure. First, the probability distribution of intensities for two channel images is calculated. In the second step, intensity correction forces, that tend to minimize image entropies, are estimated for every image voxel. Third, inhomogeneity correction fields are obtained by regularization and normalization of all voxel forces, and last, corresponding partial inhomogeneity corrections are performed separately for each channel. The method was quantitatively evaluated on simulated and real MR brain images. The results show substantial improvement in comparison with the two state-of-the-art methods.