Artifacts in magnetic resonance imaging of the spine after surgery with or without implant.

Magnetic resonance (MR) imaging is often disturbed after spine surgical procedures with or without an implant. Artifacts are induced by ferromagnetic or nonferromagnetic implants and devices and by small metallic particles left by surgical instruments. All metallic artifacts can affect the quality and usefulness of postoperative spine MR examinations. The physical effects caused by the introduction of metal or other conductive materials into a magnetic field and their consequences are presented. The application to postoperative spine MR examinations and solutions to reduce artifacts are discussed.