START WITH THE PATTERN
The shape and location of an artifact give clues to its cause.
Truncation, also called Gibbs ringing, creates alternating bright and dark lines beside a sharp high-contrast boundary. It happens because MRI samples only a finite portion of k-space and cannot reproduce the edge perfectly.
Zipper artifact appears as one or more narrow lines or bands when unwanted radiofrequency energy enters the receive system.
Shading is a broad region of uneven brightness caused by nonuniform signal reception, coil setup, positioning, B1 variation, dielectric effects, or another system-related problem.
MATCH WHAT YOU SEE
Each artifact leaves a different visual fingerprint.
Alternating bright and dark bands run parallel to a sharp boundary, often more noticeably in the lower-resolution phase direction.
A bright or dark line or band crosses the image at a consistent position because unwanted RF signal entered the data.
One region looks darker or brighter than expected instead of showing a narrow line or repeating edge ripples.
CORRECT THE CAUSE, NOT JUST THE APPEARANCE
Use a focused response for each pattern.
Add phase-encoding steps or use an appropriate reconstruction filter. More resolution may increase time and reduce SNR; smoothing may blur detail.
Confirm the RF door is fully closed, remove unapproved electronics, repeat when appropriate, and escalate persistent interference according to site policy.
Inspect coil selection and connection, patient centering, coil coverage, anatomy-to-coil distance, calibration, and protocol-specific B1 options.
An artifact that repeats across patients, coils, or protocols may indicate equipment, shielding, or environmental interference. Document the pattern and conditions, protect the clinical exam, and follow the facility's service and quality-control process.
EDGE, LINE, OR AREA
Describe the shape before touching a parameter.
Repeated lines beside a sharp border suggest truncation.
A narrow band across the image suggests zipper interference.
Broad uneven brightness suggests shading or nonuniformity.
Remember: Edge, line, or area tells you where to begin.
CHECK YOUR UNDERSTANDING
Name the pattern, then choose the first check.
Alternating bright and dark lines follow the edge of the spinal cord. What is the likely artifact?
Truncation, or Gibbs ringing. Review acquired spatial resolution and any approved reconstruction filtering.
A narrow line crosses every image after an electronic device was brought near the scan room. What should you suspect?
RF interference producing a zipper artifact. Follow site policy to remove or isolate the source and confirm the RF door and shielding conditions.
One side of the anatomy is broadly darker without a narrow line or repeated edge bands. What should you check first?
Start with coil selection and connection, patient centering, coil coverage, calibration, and possible B1 or dielectric nonuniformity.
LESSON 33 COMPLETE
You can separate ringing, RF interference, and broad signal nonuniformity before choosing a correction.Educational references
Artifact appearance and correction vary with the scanner, coil, sequence, reconstruction, field strength, and environment. Follow approved protocols, quality-control procedures, and service guidance.