Nuclear magnetic resonance, as the name implies, is a very powerful magnetic field, the magnetic field strength can reach 3T, commonly used 1.5T and 3T is 1.5 Tesla and 3 Tesla. There will be a strong attraction to all ferromagnetic metals, such as a coin in the pocket, when close to the magnet the coin will be quickly sucked out of the pocket, if one is not careful, the coin may hit the body or hit the eye, which can cause very obvious damage to the patient. If the metal objects are relatively large, such as oxygen tanks, stretchers, hospital beds, wheelchairs, this will bring about very serious personal injury accidents, which often will make the patient or the person accompanying the patient will have a life-threatening accident. Therefore, it is important to listen to the arrangements of the MRI room staff before the MRI process and not to barge into the MRI scanning room. It is also very dangerous to be in the MRI room if the patient is wearing electronic items that can damage the patient, such as pacemakers, such as insulin pumps, cochlear implants, brain stimulation electrodes and other electronic items. Therefore, during the MRI process, it is important to listen to the instructions of the MRI room staff and obey the warnings of the MRI room staff about safety before the examination and pay attention to safety. The magnetic field is not only present when the MRI is turned on, but also exists all the time, so you must pay attention to safety.