Cranial plain scan, including cranial CT scan and cranial MRI scan, is a common imaging tool used to observe whether there is organic damage in the brain. CT scan can also detect intracranial tumors, which may appear as mixed density or low density with obvious occupying effect, and there are obvious low density edema bands around the tumor. Magnetic resonance plain scan is more delicate than CT, and can detect cerebral infarction lesions in the acute stage and distinguish them from old lesions, but it is less sensitive than CT in the differential diagnosis of cerebral hemorrhage. For the examination of tumors MRI is more sensitive and has a higher positive detection rate. For inflammation and demyelinating diseases, MRI plain scan examination can also detect abnormalities.