MRI Artifacts: Zipper Artifact Prevention

MRI Artifacts

• MRI artifacts are spurious findings in or distortion of an image that can impact the diagnostic utility of MRI scans.
• Understanding the nature and causes of MRI artifacts is essential for radiologists and technologists to minimize their occurrence and optimize image quality.

Types of MRI Artifacts

Zipper Artifact

• Caused by alternating bright and dark pixels running through the image in the phase-encoding or frequency-encoding direction.
• Prevented by checking the door is closed, checking the door seal is intact, removing electrical equipment, checking for blown bulbs in the scanner room, using MRI compatible monitoring equipment, and regularly performing quality control tests.

Chemical Shift Artifact

• Caused by spatial mis-registration between fat and water signals.
• Can be reduced through adjusting imaging acquisition parameters, swapping phase- and frequency-encoding directions, increasing receiver bandwidth, and applying fat suppression.

Crisscross Artifact

• Caused by data processing or reconstruction error.
• Prevented by reconstructing the image again, increasing the frequency matrix, decreasing slice thickness, using wide bandwidth techniques, and increasing gradient strength.

Aliasing or Phase Wrapping Artifact

• Caused by phase encoding errors, occurring when object dimensions exceed the defined field of view (FOV).
• Prevented by enlarging the FOV, using pre-saturation bands on areas outside the FOV, using anti-aliasing software, switching the phase and frequency directions, and using a surface coil to reduce the signal outside of the area of interest.

Magic Angle Artifact

• Primarily affects structures with parallel fibers such as tendons and ligaments.
• Occurs when parallel bands are oriented 55 degrees to the main magnetic field, increasing signal intensity.
• Prevented by using a lower field strength, adjusting imaging parameters such as changing the angle of the imaging plane, increasing the repetition time (TR), and using a lower field strength.

Motion Artifacts

• Caused by respiration, the beating heart, and peristalsis.
• Prevented by reconstructing images with data not affected by motion and using fast MRI sequences to reduce scan time and patient motion.

Flow-Related Artifacts

• Caused by flowing blood and CSF flow, occurring in the phase-encoding direction.
• Prevented by changing the phase encoding direction.