Cranial MRI refers to cranial magnetic resonance examination, which is a commonly used imaging tool. The imaging principle is to use different tissues in the body to resonate in a magnetic field and produce different signals to lead to imaging. The signal level varies, for example, bone tissue, tumor tissue, muscle tissue, fat tissue, and bleeding tissue all have different signal values. Magnetic resonance imaging is clearer and more accurate than cranial CT, and it has a significant advantage in the examination of cerebral infarction, which can identify new acute cerebral infarction and old cerebral infarction. Magnetic resonance includes many items, including diffusion phase, T1 phase, T2 phase, Flair phase, as well as corresponding wave spectroscopy, enhancement scan, functional imaging, etc. It is widely used in the diagnosis and differential diagnosis of cerebrovascular diseases, demyelinating diseases, brain tumors, congenital developmental malformations of the cranial brain, cranial trauma, intracranial infections due to various causes and brain degenerative diseases.