Currently, with the continuous development of interventional technology, more and more patients have medical devices such as vascular stents, blockers, prosthetic valves, and pacemakers placed in their bodies due to their medical conditions. Magnetic resonance imaging (MRI) is increasingly used as a non-invasive imaging technique in clinical practice. Therefore, patients and even healthcare professionals often ask whether MRI can be performed after interventional procedures due to the placement of devices containing metal materials in the body. According to the principles of physics, a magnetic field can have three effects on magnetic materials: 1) A magnetic field causes movement and displacement of metal objects. 2, the magnetic field causes the metal material to produce current and thermal effects, so that the local temperature increases. 3. Metal objects produce artifacts that affect the imaging of perimetric structures. Therefore, questions about the safety of MRI examinations can be summarized into two points: 1) Will the magnetic force of the magnetic field displace the implanted device? 2. Will the current and thermal effects of the magnetic field damage these devices, affect their function, or increase the associated complications? This is detailed in the 2010 Expert Consensus on Cardiovascular Magnetic Resonance developed by the American College of Cardiology Foundation. Most cardiovascular devices today are made of non-magnetic or weakly magnetic materials. Cardiovascular devices made of non-magnetic materials allow for MR exams immediately after implantation. Implanted devices containing weakly magnetic materials are generally ready for MR examination 6 weeks after surgery. In general, implanted devices that are stably fixed in the heart or in the vessel wall do not shift in the magnetic field of MRI examinations. The following are the specifics of the MR environmental safety of various in vivo implanted devices: 1. Vascular stents Both in vitro and clinical studies have shown that the magnetic field effects of MRI have no effect on the safety of bare coronary stents and drug-coated stents and do not increase the incidence of in-stent thrombosis, heat generation, poor wall apposition, stent displacement, coronary restenosis, and adverse events. Therefore, coronary stents (including drug-coated stents) can be subjected to MR examination at 3T or less field strength at any time after implantation. Local artifacts from stents do interfere with image evaluation, however. The situation is similar for aortic stents, where nonmagnetic stents can undergo MRI with a field strength <3T immediately; weak magnetism requires an appropriate delay until 6 weeks later. However, certain types of aortic stents have a strong susceptibility to magnetization, especially zenithaaa have shown strong deflective and torsional forces in the magnetic field test, and magnetic resonance examination can in principle not be performed for these stents. 2.Heart blocker Similar to vascular stents, the metal part of the commonly used heart blockers is mainly nickel-titanium alloy, and the non-magnetic ones can do MRI immediately, while the weakly magnetic ones need to be postponed until 6 weeks after surgery. Earlier spring coils used for embolization of arterial catheters were made of stainless steel, but those currently used are made of platinum or other alloys, which are basically nonmagnetic or weakly magnetic, so the principles are similar. 3, Prosthetic Heart Valves and Valvuloplasty Rings Studies have shown that the force of surgical sutures holding prosthetic ring tissue in place is much greater than the magnetic force generated by a magnetic field of 4.7 T. The magnetic effect of MR magnetic fields on prosthetic valves is much less than the impact of heartbeats and blood ejection on the valves. The thermal effect of MR magnetic fields on prosthetic valves is also minimal, with local temperature increases generally less than 1°C, while blood flow quickly removes the heat. Therefore, at field strengths of 3 T or less, tested prosthetic heart valves or valvuloplasty rings can be safely examined by MRI at any time after surgery. The local artifacts of the prosthetic valve generally do not interfere with the observation of MRI images. Pacemakers and implantable cardioverter-defibrillators (ICDs) Although pacemakers have been available since 2000 that can withstand strong magnetic fields of 1.5 fields under certain conditions and operating modes, in general, the magnetic precision electronics contained in pacemakers and ICDs can be severely affected by magnetic fields and have adverse consequences, making them strong contraindications to routine MR examinations. MR is discouraged even in patients who do not rely exclusively on pacemaker pacing, unless MR is the only alternative and necessary test, and must be done by both electrophysiologists and MR imaging specialists at an experienced center, after the patient has signed an informed consent form, and with advanced life-support equipment and specialists. 5. Other implanted devices Swan-Ganz floating catheters placed in the body are not suitable for MR examinations because of the magnetic material contained in the lead, but pulmonary artery catheters without sensing devices attached are acceptable for MRI examinations. Temporary pacing leads placed transvenously are not suitable for MR examinations, but temporary pacing leads secured to the epicardium are safe. Cardiac support devices such as aortic balloon counterpulsation pumps and ventricular assist devices are absolute contraindications to MRI because of their high magnetic content. Artificial hip joints and wires used to suture the sternum in cardiothoracic surgery are made of non-ferromagnetic materials, so they are safe in the MR environment. Some older models of cerebrovascular clamps are unsafe under MR and require special attention. The American Society for Testing and Materials (ASTM) classifies the safety of items in the MR environment into three categories, 1. MR safe: items that are not dangerous in any MR environment. Stents, blockers, and artificial heart valves with this designation can be safely examined in MR at any time after implantation into the body. 2.MR Conditional Safety: Safe in specific MR environments and for specific uses. 3, MR Unsafe: Dangerous in all MR environments. MR safety information for each medical product can be found in its product specification.