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Arachnoid Granulation
1/288
Demographics:
Indication: Headache

Arachnoid Granulation

Findings

  • Small rounded filling defect within the right transverse sinus, compatible with an arachnoid granulation.

Diagnosis

Arachnoid Granulation Mimicking Thrombus

Discussion

  • Arachnoid granulations are common, with a prevalence of approximately 60%.

    • They are protrusions of arachnoid through the dura mater, which allow CSF to extend from the subarachnoid space into the venous sinus or into the calvarium.

    • They most commonly occur in the superior sagittal and transverse sinuses.

    • On non-contrast head CT they are CSF density and on post-contrast imaging they appear as round, focal filling defect in the dural sinus.  Usually they are small (<10mm), but occassionally can be "giant" (>10mm).  If they involve the calvarium, they appear as a circumscribed lucent lesion.

    • Usually these granulations are easy to differentiate from thrombosis given their round, well-circumscribed appearance and typical location.

Annotated Images & Illustrations

arachnoid granulation

arachnoid granulation

References

  • Cerebral Venous Thrombosis and Multidetector CT Angiography: Tips and Tricks. Mathieu H. Rodallec, Alexandre Krainik, Antoine Feydy, Annick Hélias, Jean-Michel Colombani, Marie-Christine Jullès, Véronique Marteau, and Marc Zins. RadioGraphics 2006 26:suppl_1, S5-S18

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