Pitfalls and artifacts encountered in clinical MR imaging of the spine.

Magnetic resonance (MR) imaging of the spine has become widely accepted as a valuable diagnostic tool. However, there are a number of artifacts and pitfalls associated with spinal MR imaging. Chemical shift artifacts may be induced by bone marrow, epidural fat, or intradural fat. Motion artifacts arise from several sources, which include respiration, flow of fluids, and swallowing. Artifacts due to a nonuniform magnetic field are particularly noticeable within trabecular bone or at bone-soft tissue interfaces but may also be caused by incomplete fat saturation or the presence of metal near the spine. Protocol errors may cause artifacts such as saturation, phase wraparound, truncation, radio-frequency interference, shading, and partial volume averaging. Use of fat saturation, use of motion and flow compensation, and careful screening of patients for metal in clothing can help reduce the occurrence of artifacts. In addition, use of an optimal imaging technique is essential and should include use of the proper surface coil, field of view, and pulse sequence.