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CSF Flow Artifact


KEY FACTS

Terminology

  • Cerebrospinal fluid (CSF) flow-related phenomenon due to time of flight (TOF) effects and turbulent flow

Imaging

  • Location: Intrathecal, subarachnoid space

    • Most prominent in cervical and thoracic spine

  • Low or high signal intensity

  • Ill-defined margins

Top Differential Diagnoses

  • Vascular malformation, type I dural arteriovenous fistula

  • Vascular malformation, type IV arteriovenous fistula

  • CSF drop metastases

Clinical Issues

  • Time of flight effects

    • Dark CSF signal

    • Positive relationship between CSF velocity and TOF losses

    • Typically occurs in spin-echo or fast spin-echo imaging

  • Flow-related enhancement produces bright CSF signal

  • Turbulent flow

    • Abnormally dark signal intensity

  • Ghosting artifact motion

    • Periodic motion, such as CSF pulsation, cardiac motion, and respiratory motion

Diagnostic Checklist

  • Flow artifacts frequently have bizarre nonanatomic appearance

  • Cross-reference other imaging planes and compare with faster imaging sequences (GRE, true FISP) that reduce superimposed flow phenomenon

  • Ghosting artifacts in phase-encoding direction often accompany TOF- and FRE-related signal changes, help point out true nature of those changes

Sagittal STIR MR shows an ill-defined signal void in the dorsal subarachnoid space of the thoracic spine
. This artifact is due to a combination of respiratory and cardiac-related pulsatile cerebrospinal fluid (CSF) flow superimposed on cranially directed bulk CSF flow. There is also contribution from turbulent CSF flow moving from the ventral to dorsal subarachnoid space. This complex CSF motion results in phase incoherence, leading to signal loss.

Axial T2WI MR confirms the CSF flow artifact
.

Axial T1WI MR depicts isointense CSF flow artifact dorsal to the thoracic cord in the subarachnoid space
.

Sagittal T1WI MR exhibits syringomyelia in the cervical cord
. CSF flow dynamics are altered because of the cerebellar tonsillar ectopia
. The turbulent flow results in a broader spectrum of proton velocities, which result in more rapid dephasing and signal loss. There is also a positive relationship between CSF velocity and time of flight losses.

TERMINOLOGY

Definitions

  • CSF flow-related phenomenon due to time-of-flight (TOF) effects, turbulent flow

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