MRI is mainly imaging by magnetic field and electromagnetic waves, and there is no ionizing radiation, unlike the commonly used X-rays and CT. Therefore, MRI is free of ionizing radiation when examining various parts of the body, including the brain, spinal cord, chest and abdomen, pelvis, and various parts of the bones and joints, and MRI can be called a green examination method. MRI has a very powerful diagnostic value for the brain and spinal cord, often referred to as the central nervous system, such as cerebral infarction, cerebral hemorrhage, vascular malformations, as well as brain tumors, encephalitis and brain degenerative disease, and white matter disease. MRI can be used for multiple examinations of brain tissue lesions for pre-treatment diagnosis and post-treatment efficacy assessment, and because there is no radiation, it is generally acceptable to patients. MRI has a high soft tissue resolution and is very accurate for diagnosis. However, there are patient requirements for MRI of the brain, such as no pacemakers, insulin pumps, hearing aids, neurostimulation electrodes, cochlear implants, etc. During the examination, there may be noise and fever, which is normal. Patients will be given headphones or cotton balls to reduce the impact of noise. The length of the examination is about eight minutes, so most patients can cooperate. MRI is not radioactive and is good for diagnosis and efficacy assessment.