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Epilepsy Advanced Magnetic Resonance Imaging in Epilepsy Heath Pardoe, PhD and Ruben Kuzniecky, MD Epilepsy Neuroimaging Laboratory, NYU Epilepsy Center, Department of Neurology, NYU School of Medicine, New York, New York, US Abstract Magnetic resonance imaging (MRI) is the most commonly used noninvasive imaging modality for epilepsy diagnosis, etiologic classification, and management. The availability of 3T scanners and multiple channel coils mean isotropic T2-weighted MRI can also be readily obtained with a similar spatial resolution to T1w MRI. These acquisitions in combination with quantitative morphometric techniques can be used to detect subtle cortical and subcortical brain abnormalities associated with epilepsy. Functional MRI (fMRI) methods including electroencephalography (EEG)-fMRI and resting state imaging have been used to study network activity, such as language and memory in surgical candidates. Diffusion MRI can be used to map white matter pathways and provide an alternative structural view of connections between brain regions. These techniques will increase the yield of abnormalities in epilepsy patients previously considered nonlesional. Keywords MRI, epilepsy, neuroimaging, surgery, MR spectroscopy Disclosure: Heath Pardoe, PhD, and Ruben Kuzniecky, MD, have no conflicts of interest to declare. No funding was received for the publication of this article. Received: September 23, 2014 Accepted: October 15, 2014 Citation: US Neurology, 2014;10(2):104–8 Correspondence: Ruben Kuzniecky, MD, NYU Epilepsy Center, 223 East 34th St, New York, NY 10016. E: ruben.kuzniecky@nyumc.org Acknowledgments: The authors are supported in part by grants from Finding a Cure for Epilepsy and Seizures (FACES), the Human Epilepsy Project (HEP) via the Epilepsy Study consortium, and NIH-NINDS RO1NS090417. Magnetic resonance imaging (MRI) is the most commonly used noninvasive imaging modality for epilepsy diagnosis, etiologic classification, and management. MRI is mandatory for all patients with new onset epilepsy, particularly for those who do not respond to medication. The primary aim of MRI scanning in an individual with epilepsy is to uncover abnormal brain regions that are associated with seizures. Modern MRI-based methods may be used to reveal discrete structural and functional brain abnormalities or distributed network changes. In this article we review recent developments in MRI for individuals with epilepsy. The most effective intervention for medically intractable epilepsy is surgical resection, although alternative interventions, such as the ketogenic diet and neurostimulation approaches, may also be used. Surgical outcomes have improved over the last 30 years and this is likely partly due to improvements in MRI technology and availability. 1 A predictor of a good surgical outcome is the identification of a lesion on MRI. 2 A focus of current research is to improve lesion detection using improved structural image acquisition protocols and postprocessing methods. As well as identifying a part of the brain to remove, it is also important to identify brain regions that are functionally critical. Functional MRI (fMRI) techniques, comprising task-related or resting state blood oxygenation level dependent (BOLD) imaging, can be used to estimate language networks and lateralization and memory networks, and may therefore inform the presurgical planning process. Similarly, diffusion MRI (dMRI) is becoming widely used in research settings to image white 104 matter pathways. Although this is still a nascent technology, an example of a useful application of diffusion MRI is to image the optic radiations and therefore assist the surgeon in avoiding the Meyer loop and preventing visual field deficits following anterior temporal lobectomy. 3 Structural Magnetic Resonance Imaging Most modern epilepsy imaging protocols include a whole brain T1-weighted MRI scan. Voxel resolution is of the order of 1  mm. Current acquisitions are typically isotropic, and most modern MRI viewing software packages allow these images to be resliced to any preferred plane. These acquisitions provide a detailed anatomical image that can be used to identify epilepsy- related brain abnormalities. Examples of these abnormalities include focal cortical dysplasia, which may be associated with thickened cortex and blurred boundary between the neocortical gray matter layer and underlying white matter; reduced hippocampal volume in association with hippocampal sclerosis in temporal lobe epilepsy (TLE); heterotopic gray matter in periventricular nodular heterotopia or subcortical band heterotopia; and a variety of cortical folding abnormalities in association with other malformations of cortical development, such as lissencephaly/ agyria and polymicrogyria. 4 Two of the most relevant improvements in MRI hardware are the routine use of 3T MRI scanners and the availability of multiple channel receive coils. 3T MRI provides higher signal than 1.5T imaging, which may be used to reduce © TOU C H ME D ICA L ME D IA 2014