This needs to be analyzed specifically, it depends on the material of the implant, if it is stainless steel, it cannot be done, if the implant is made of titanium, 1.5T MRI can be done. However, usually the hospital radiologist, will ask the patient to consult the original surgeon to see if the implant material is MRI compatible. Nowadays, the outer packaging of a cardiac stent will state whether it is MRI compatible or not.
If it is MRI compatible, then it can be done. The material of artificial joint prostheses is usually cobalt-chromium-molybdenum alloy, which is also stable for implantation, so it is also MRI-compatible. internal fracture fixation plates are mostly made of titanium alloy, which is also MRI-compatible.