CSF Flow Artifacts¶

Overview¶

CSF pulsation creates motion artifacts on spine MRI that can mimic intradural pathology. These artifacts result from CSF flowing in synchrony with the cardiac cycle — systolic flow produces phase-encoding ghosts that project across the image.

Appearance¶

Smeared signal or ghost images within the thecal sac, typically in the phase-encoding direction
Can mimic intradural masses, arachnoiditis, or filling defects
Most prominent in the thoracic spine (where the subarachnoid space is largest relative to the cord)
More conspicuous on T2-weighted sequences (where CSF is bright)

How to Recognize¶

The artifact repeats at regular intervals in the phase-encoding direction
The artifact "moves" if the phase-encoding direction is changed
Flow artifacts do not persist on post-contrast T1 images
Cardiac-gated sequences reduce or eliminate the artifact

Mitigation¶

Cardiac gating — Synchronizes acquisition with the cardiac cycle
Flow compensation (gradient moment nulling) — Reduces phase errors from flowing CSF
Spatial saturation bands — Placed above and below the imaging volume to suppress inflowing CSF
Swap phase/frequency direction — Moves the artifact away from the area of interest

Clinical Pearl

When you see a questionable intradural filling defect on T2-weighted thoracic spine MRI, consider CSF flow artifact before calling it pathology. The clue: the artifact repeats in the phase-encoding direction and is not visible on T1 post-contrast images. If uncertain, repeat with cardiac gating or swap the phase-encoding direction.

Key Points¶

CSF pulsation creates ghost images that can mimic intradural pathology
Most common in the thoracic spine on T2 sequences
Repeating pattern in the phase-encoding direction is the clue
Cardiac gating and flow compensation reduce the artifact
Always correlate with T1 post-contrast if an intradural lesion is suspected

References¶

Pai V, Boutet A, Malik M, et al. Differentiating CSF flow artifacts from pathology: an educational review. Insights Imaging. 2025;16:288. PMCID: PMC12722609. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC12722609/
Quint DJ, Patel SC, Sanders WP, Hearshen DO, Boulos RS. Importance of absence of CSF pulsation artifacts in the MR detection of significant myelographic block at 1.5 T. AJNR Am J Neuroradiol. 1989;10(5):1089-1095. PMID: 2505525. Available from: https://pubmed.ncbi.nlm.nih.gov/2505525/
Ehman RL, Felmlee JP. Flow artifact reduction in MRI: a review of the roles of gradient moment nulling and spatial presaturation. Magn Reson Med. 1990;14(2):293-307. PMID: 2345509. Available from: https://pubmed.ncbi.nlm.nih.gov/2345509/
Wymer DT, Patel KP, Burke WF 3rd, Bhatia VK. Phase-Contrast MRI: Physics, Techniques, and Clinical Applications. RadioGraphics. 2020;40(1):122-140. PMID: 31917664. Available from: https://pubmed.ncbi.nlm.nih.gov/31917664/
CSF turbulent flow MRI artifact. Radiopaedia.org. Available from: https://radiopaedia.org/cases/mri-artifact-by-csf-turbulent-flow-1