[11C] -verapamil PET will be used as a surrogate marker of P-gp expression in patients with epilepsy, and will be an important prognostic factor of individualized drug therapy. Also, it can be used as a biomarker in checking of the drug efficacy of novel medications. Furthermore, by localizing epileptogenic zones for patients, [11C] -verapamil PET could contribute in improving the prognosis of surgical treatment in drug resistant epilepsy.