Epilepsy is a common disease affecting 0.5 to 1% of the general population. Epilepsies refractory to drug treatment lead to increased morbidity, mortality and high costs for public health (representing 75% of the costs associated with epilepsy is among the most costly diseases in Neurology). The only curative therapy is surgical removal or disconnection of the epileptogenic network. To do this, a comprehensive presurgical evaluation is essential to accurately define the location of the epileptogenic zone (EZ) and its relationship with the functional areas that must be preserved. This approach requires in some cases intracerebral EEG recordings. This latter technique, expensive and invasive, remains at present, the standard method in the location of the ZE. In this context, the development of non-invasive and inexpensive methods is a priority in the field. Moreover, many fundamental studies have shown changes in ion homeostasis including sodium associated with hyperexcitability related to epilepsy. The investigators team at CEMEREM, CHU Timone, specialized in the development and validation of innovative methods in MRI, has developed an in vivo sodium MRI acquisition and processing of data unique in France, capable of quantifying the intracerebral sodium concentration in three dimensions in a completely non-invasive and non-irradiating manner

Inclusion Criteria:

• Patient presenting a drug-resistant partial epilepsy for which an indication is indicated after préchirugical balance assessment.
• Patient not presenting a psychiatric disease chronicles, an demential syndrome,
• Patient not presenting contraindication to the realization of an examination by MRI

Exclusion Criteria:

• Patient suffering a not operable shape of partial epilepsy or a generalized epilepsy
• Patient suffering an evolutionary associated serious illness (cancer, autoimmune disease, hepatic insufficiency)