MRI is not harmful to the body because the principle of MRI examination is to scan by magnetic field and it has no radiation. MRI is different from CT, which has radiation. Currently, MRI can be performed on a fetus and has no effect on the fetus. However, if the patient has a metal implant in the body, MRI cannot be performed because it will cause the metal implant to shift in the body and cause unnecessary damage to the body. Therefore, before the MRI is performed, the patient will be asked in detail whether there are any metal implants placed in the body, and whether a heart stent or pacemaker has been placed recently.