Artifacts in CT

An artifact is a false image on CT that does not match the true anatomy. Artifacts can obscure results, but radiologists can usually recognize most artifact patterns.

Common artifact types

Metal artifacts arise from implants such as joint replacements, bone plates, or aneurysm clips that absorb rays excessively. Dark and bright streaks often appear around metal.

Motion artifacts appear when the patient moves during scanning, for example from coughing, breathing, or heartbeat. The image looks blurred or streaked.

Other artifacts to recognize

Beam hardening occurs when the beam loses energy passing through dense bone, causing dark areas nearby. These artifacts often appear between the bones at the base of the skull.

Partial volume artifacts occur when a single slice contains two different tissues, so the boundary of an organ appears unclear.

How they are managed

Modern technology offers metal artifact reduction (MAR) algorithms and iterative reconstruction that reduce interference. Patients are also coached on breathing and holding still.

If artifacts still interfere, the doctor may request a repeat study with a different technique or use MRI as a complement.

Key points

• Metal implants or patient movement can cause artifacts.
• Radiologists usually recognize them when reading results.

Educational information, not a substitute for medical advice.