Extra-Axial Flow Voids



Extra-Axial Flow Voids


James D. Eastwood, MD



DIFFERENTIAL DIAGNOSIS


Common



  • Normal (Normal Arteries, Veins)


  • CSF Pulsation


  • Saccular Aneurysm


  • Fusiform Aneurysm, ASVD


  • Arteriovenous Malformation


  • Developmental Venous Anomaly


Less Common



  • Dural A-V Fistula


  • Thrombosis, Dural Sinus


  • Fusiform Aneurysm, Non-ASVD


  • Dissecting Aneurysm


  • Pseudoaneurysm


Rare but Important



  • Vein of Galen Malformation


  • Venous Varix


ESSENTIAL INFORMATION


Key Differential Diagnosis Issues



  • Vascular vs. CSF flow void (FV)



    • Vascular FVs sharply demarcated from surrounding CSF


    • If large, vascular FVs may cause phase artifact


  • Vascular FV vs. acutely thrombosed artery/vein



    • Thrombus iso- on T1, hypointense on T2WI, can mimic FV


    • Do T2* (GRE/SWI) → clot “blooms”


Helpful Clues for Common Diagnoses



  • CSF Pulsation



    • Ill-defined signal loss near artery


  • Saccular Aneurysm



    • Typically involve major branch points


  • Fusiform Aneurysm, ASVD



    • Long segment & focal outpouching (BA > ICA/branches)


  • Arteriovenous Malformation



    • Extra-axial feeding, draining vessels


    • Look for aneurysms (feeding arteries, intranidal), venous varices


  • Developmental Venous Anomaly



    • Draining vein & enlarged medullary veins


    • T1 C+ best sequence


Helpful Clues for Less Common Diagnoses



  • Dural A-V Fistula



    • Older; usually prior dural sinus thrombosis


    • Direct AV shunt


  • Thrombosis, Dural Sinus



    • Prominent collateral veins


  • Fusiform Aneurysm, Non-ASVD



    • Often more distally located than ASVD


    • Vasculopathy, vasculitis, mycotic, oncotic


  • Dissecting Aneurysm



    • Extra- > intracranial; VA > supraclinoid ICA


Helpful Clues for Rare Diagnoses



  • Vein of Galen Malformation



    • ↑ VOG, feeding/draining vessels


  • Venous Varix



    • Seen with AV shunting, venous strictures






Image Gallery









Axial T2WI MR shows paired ACA flow voids “on end” image, curvilinear MCA flow voids image, internal cerebral veins image, proximal straight sinus image, & superior sagittal sinus image.

Only gold members can continue reading. Log In or Register to continue

Related posts:

Falx Lesions Multiple Hypointense Foci on T2 Solitary Parenchymal Calcification Bithalamic Lesions Fusiform Arterial Enlargement Enlarged Neural Foramen

Stay updated, free articles. Join our Telegram channel
Tags:
Aug 7, 2016 | Posted by in NEUROLOGY | Comments Off on Extra-Axial Flow Voids

Full access? Get Clinical Tree

 Get Clinical Tree app for offline access