Neurosurgery (or neurological surgery) is the medical specialty concerned with the prevention, diagnosis, treatment, and rehabilitation of disorders which affect any portion of the nervous system including the brain, spinal cord, peripheral nerves, and extra-cranial cerebrovascular system. Neuroradiology methods are used in modern neurosurgical diagnosis and treatment, including computer assisted imaging computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), magnetoencephalography (MEG), and the stereotactic surgery. Some neurosurgical procedures involve the use of MRI and functional MRI intraoperatively.