Truncation Artifact¶

Overview¶

Truncation artifact (Gibbs ringing) appears as alternating bright and dark lines parallel to sharp high-contrast interfaces. It is most commonly at the skull-brain and cord-CSF interfaces, and can mimic an intramedullary lesion such as syringomyelia ("pseudosyrinx").

Appearance¶

• Thin, linear, alternating bright and dark lines within the spinal cord, parallel to and adjacent to the cord-CSF boundary
• Most conspicuous on sagittal T2-weighted images where the cord-CSF contrast is highest
• The "pseudosyrinx" — a linear bright line within the cord center on T2 that is actually truncation artifact, not a true syrinx

How to Recognize¶

• The line is perfectly centered within the cord and perfectly parallel to the cord margins
• The line is present on sagittal images but NOT on axial images (a true syrinx is visible on both)
• The line spans the entire cord without focal expansion
• Higher matrix size (more phase-encoding steps) reduces or eliminates the artifact

Key Points¶

• Alternating bright/dark lines at high-contrast interfaces (cord-CSF boundary)
• Can mimic syringomyelia on sagittal T2 images
• Not visible on axial images — this is the key to recognition
• Higher matrix size reduces the artifact
• Always correlate sagittal and axial images

References¶

1. Czervionke LF, Czervionke JM, Daniels DL, Haughton VM. Characteristic features of MR truncation artifacts. AJR Am J Roentgenol. 1988;151(6):1219-28. https://pubmed.ncbi.nlm.nih.gov/3263776/
2. 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):1499-521. https://pubmed.ncbi.nlm.nih.gov/9821197/
3. Hakky M, Pandey S, Kwak E, Jara H, Erbay SH. Application of basic physics principles to clinical neuroradiology: differentiating artifacts from true pathology on MRI. AJR Am J Roentgenol. 2013;201(2):369-77. https://pubmed.ncbi.nlm.nih.gov/23883218/
4. Phillips C, Bagley B, McDonald MA, Schuster NM. Gibbs or truncation artifact on MRI mimicking degenerative cervical myelopathy. Pain Med. 2022;23(4):857-859. https://academic.oup.com/painmedicine/article/23/4/857/6472362
5. Tarafdar S, Mohan A, Nagarajan K. The "Lip Sign" in MRI of the spinal cord. Korean J Radiol. 2019;20(10):1474-1475. https://www.kjronline.org/DOIx.php?id=10.3348/kjr.2019.0486
6. Gibbs and truncation artifacts. Radiopaedia. https://radiopaedia.org/articles/gibbs-and-truncation-artifacts

Related Articles¶

• Syringomyelia
• MRI Artifacts and Pitfalls