To do an MRI, remove the metal objects from your body, mainly to avoid danger. MRI, also known as nuclear magnetic, magnetic resonance, its imaging principle is to use the phenomenon of interaction between atomic nuclei and radio frequency magnetic field in the human body under certain conditions to achieve the purpose of image. When ferromagnetic objects, such as pens, wheelchairs, oxygen tanks, etc., are brought into the high magnetic field of high-speed MRI, the “missile effect” or projection injury may occur, endangering the health of patients, accompanying family members or medical personnel, and damaging expensive MRI machines. In addition, it may also cause the following: 1) affect the judgment of examination results: the uniformity of the magnetic field may be affected during the examination, causing interference with the image, forming artifacts, which is not conducive to the display of lesions; 2) affect the function of pacemakers and cochlear implants: under the action of strong magnetic field, the function of pacemakers and cochlear implants may be damaged, resulting in their failure; 3) damage important organs and large blood vessels: under the action of magnetic field It may cause metal implants to shift, fall off, deform or warm up, such as aneurysm clips, intra-articular fixation devices, drug infusion devices, etc., which can easily cause harm to patients and even damage important organs and large blood vessels; 4. Lead to object demagnetization: magnetic field can also affect the functions of cell phones, watches, magnetic data storage devices and precision instrumentation devices, such as magnetic card demagnetization, etc. Therefore, before entering the scanning room for MRI examination, you need to leave the metal objects you carry with you, such as cell phones, watches, hair clips, metal jewelry, belts, metal buttons, pocket knives, magnetic data storage devices, credit cards, movable dentures, prostheses, hearing aids, etc. in the waiting room. If a person contains metal stents, pacemakers, artificial heart valves, artificial corneas, post-vascular surgery metal clips, tracheal intubation, contraceptive rings, metal foreign bodies and artificial joints, please declare this to your physician to confirm whether this test can be performed. It should be clear that for metal implants such as artificial joints, which are mainly made of titanium and cobalt-chromium-molybdenum alloys, MRI is not only safe, but can also specifically evaluate joint prostheses and discover the cause of post-surgical pain, so you can be assured that the examination will be performed after the physician’s evaluation.