Novel MR contrasts to reveal more about the brain.

Twenty percent of patients with refractory focal epilepsy have an undetermined etiologic basis for their epilepsy despite extensive investigation, including optimal MR imaging. Surgical treatment of this group is associated with a less favorable postoperative outcome. Even with improvements in imaging techniques, a proportion of these patients will remain "MR imaging-negative." It is likely, however, that some of the discrete macroscopic focal lesions that are currently occult will be identified by imaging techniques interrogating different microstructural characteristics. Furthermore, these methods may provide pathologic specificity when used in combination. The description and application of these techniques in epilepsy are the focus of this article.