If a patient has an orthopedic implant, which imaging modality can they NOT have?

• A. CT
• B. Ultrasound
• C. MRI
• D. Scintigraphy

Answer: (C)

Magnetic resonance imaging is limited by the presence of metal because it relies on strong magnetic fields and radiofrequency energy. Metal implants can interact with the magnetic field, causing heating, risk of movement or torque, and significant distortion or artifacts in the image. Because of safety and image quality concerns, MRI cannot be used universally in patients with orthopedic implants; some implants are labeled MR-conditional with strict precautions, but many scenarios preclude MRI. In contrast, other imaging methods like CT, ultrasound, and scintigraphy do not depend on magnetism and are generally usable to evaluate implants, though CT can still suffer from metal artifacts.