MRI Artifacts and Pitfalls¶

Overview¶

Spine MRI is susceptible to several artifacts that can mimic pathology or obscure true findings. Recognizing these artifacts is essential for accurate interpretation.

Common Artifacts¶

Motion Artifact¶

Ghosting in the phase-encoding direction from patient breathing, swallowing, or CSF pulsation
Appears as repeated images of high-signal structures (e.g., aorta, CSF) smeared across the image
Mitigation: motion-compensating sequences, saturation bands, shorter acquisition times

Susceptibility Artifact¶

Signal loss and geometric distortion at interfaces between tissues with different magnetic susceptibility (air-bone, metal-tissue)
Most prominent on GRE sequences; less on FSE
Relevant at: surgical hardware, vertebral endplates, cervicothoracic junction (lung apex)
Mitigation: FSE sequences, increased bandwidth, MARS protocols for hardware

Chemical Shift Artifact¶

Misregistration of fat and water signals at fat-water interfaces (vertebral endplates)
Appears as a bright or dark line at the endplate margin in the frequency-encoding direction
Can mimic endplate fracture or Modic changes
Mitigation: increase bandwidth, fat suppression

Wrap-Around (Aliasing)¶

Anatomy outside the field of view wraps into the image on the opposite side
Mitigation: increase FOV, phase oversampling, swap phase/frequency directions

Clinical Pearl

Susceptibility artifact from surgical hardware is the biggest challenge in post-operative spine MRI. Titanium produces less artifact than stainless steel. MARS techniques (FSE instead of GRE, increased bandwidth, STIR instead of chemical fat-sat, smaller voxels) significantly improve image quality around hardware.

Key Points¶

Motion, susceptibility, chemical shift, and truncation are the most common spine MRI artifacts
Susceptibility artifact is worst on GRE, least on FSE
MARS techniques reduce hardware artifact
Chemical shift at endplates can mimic fracture or Modic changes
CSF flow artifact is covered separately

References¶

Taber KH, Herrick RC, Weathers SW, Kumar AJ, Schomer DF, Hayman LA. Pitfalls and artifacts encountered in clinical MR imaging of the spine. RadioGraphics. 1998;18(6):1499-1521.
Noda C, Ambale Venkatesh B, Wagner JD, Kato Y, Ortman JM, Lima JAC. Primer on commonly occurring MRI artifacts and how to overcome them. RadioGraphics. 2022;42(3):E102-E103.
Olsen RV, Munk PL, Lee MJ, Janzen DL, MacKay AL, Xiang QS, Masri B. Metal artifact reduction sequence: early clinical applications. RadioGraphics. 2000;20(3):699-712.
Krupa K, Bekiesińska-Figatowska M. Artifacts in magnetic resonance imaging. Pol J Radiol. 2015;80:93-106.
MRI artifacts. Radiopaedia.org. Available from: https://radiopaedia.org/articles/mri-artifacts-1