The investigators propose a prospective study of 20 control subjects and 180 consecutive patients with possible non-convulsive status epilepticus (NCSE). The investigators will obtain three functional images of the brain: 1. Fluorodeoxyglucose positron emission tomography (FDG-PET) 2. Perfusion (and structural) magnetic resonance (MR) images 3. Computed tomography (CT) perfusion. Brain hypermetabolism/hyperperfusion is a strong argument to confirm a diagnosis of non-convulsive status epilepticus. The aim is to determine which of the three functional imaging techniques is the most sensitive and easy to obtain in the detection of hypermetabolism/hyperperfusion. The investigators will determine which EEG patterns are associated with hypermetabolism/perfusion. The investigators will further study and describe the management with antiseizure medication and outcome of the group with possible non-convulsive status epilepticus WITH hypermetabolism/hyperperfusion versus the group with possible non-convulsive status epilpticus WITHOUT hypermetabolism/hyperperfusion. The investigators will make recommendations for an imaging protocol in possible NCSE for widespread use. The aim is to offer guidelines to incorporate imaging in the diagnosis, management and prognosis of NCSE in patients with the ictal-interictal continuum.