If there are positive neurologic signs such as headache, it suggests organic brain disease. If the head CT is normal, then a head MRI is needed. Head MRI provides coronal, sagittal, and transverse three-dimensional images. It shows lesions in the brainstem and posterior cranial fossa, and shows clearly for tiny subtle tissues. The clarity is high and there is no radioactive damage to the body. Head MRI can be used to diagnose cerebral infarction, encephalitis, aneurysms, arteriovenous malformations, venous sinus thrombosis, and abnormal nerve fiber bundles in the brain from various causes. If a headache occurs, it is necessary to seek medical attention as soon as possible for examination and treatment by a specialized clinician to avoid serious complications.