Which imaging technique is contraindicated for patients with metallic implants or foreign objects?

MRI, or Magnetic Resonance Imaging, is contraindicated for patients with metallic implants or foreign objects due to the strong magnetic fields and radiofrequency energy it employs. These magnetic fields can interact with metallic implants, potentially causing movement or heating of the metal, which can lead to serious complications or injuries. For example, devices like pacemakers, aneurysm clips, or certain orthopedic hardware can malfunction or be dislodged in the presence of an MRI machine's magnetic field.

In contrast, X-rays and CT scans use ionizing radiation, which does not negatively interact with metal in the same way and are typically considered safe for patients with these implants. Ultrasound utilizes sound waves rather than magnetic fields or radiation, making it safe for individuals with metal objects in the body. Therefore, MRI is specifically noted as contraindicated, highlighting the unique risks associated with its use in patients with metallic implants.