MRI is not radioactive to the human body because it primarily uses a large number of hydrogen nuclei in the body, which are imaged by the movement of an applied magnetic field. It is different from the way the body is examined using radiation, so it is relatively safe. Some people who are sensitive to radiation, such as infants and children or women during pregnancy, may choose to have an MRI in special cases. MRI is not suitable for all kinds of diseases because it does not expose the body to radiation. Not everyone is suitable for MRI. Patients who have metal objects placed in their bodies, who have high fever, or who cannot cooperate during the examination cannot have MRI. Therefore, it is best for the patient to decide whether to have an MRI based on the doctor’s judgment.