How to Differentiate Vascular Malformations Radiologically


  • CT shows enlarged tangled vessels with curvilinear or speckled calcification; flow voids may be identified on CT with contrast in and around the region of the nidus of the brain AVM; if hemorrhagic, CT shows ICH without significant edema
  • MR shows curvilinear dark flow void in most pulse sequences
    • T1-weighted MR images show a sharply demarcated focus of low signal
    • T2-weighted images show bright lesion center, signal void demonstrates flow in AVM
  • Cerebral angiography shows the nidus configuration, its relationship to surrounding vessels and localization of the draining portion and the presence of associated aneurysms.




  • CT shows calcified hyperdense lesions that may enhance
  • MR shows hypointensities on T2WI and GRE (hemosiderin) surrounding various circumscribed regions of hemorrhage, and hyperintensities on T1WI because of methemoglobin;  (vs tumors, has a complete rim of hemosiderin); abuts ventricular or pial surfaces
    • described as “popcorn” pattern of variable intensities on T1 and T2 weighted images due to evolving blood products;  dark hemosiderin ring on T2 or GRE at periphery of lesion is suggestive of remote hemorrhage
  • Cerebral Angiography:  minimal blood flow, thus may not be seen on angiography (“angiographically occult”)






  • Linear structures with flow voids usually around ventricles with transcerebral course and uniform umbrella shaped enhancement.
  • Plain CT: usually not demonstrated
  • CT with contrast:  enlarged veins identified
  • MRI: medullary veins converge on dilated transcerebral vein with a “sunburst pattern” on enhanced T1 weighted images
  • Cerebral Angiograpy:  pathognomonic “caput medusa” appearance of radially arranged small medullary veins during late capillary or venous phase



  • Propensity for the pons
  • MRI:
    • Post contrast T1WI shows nodular enhancement
    • Isointense on T2WI
    • GRE reveals hypointensity
    • hypointense “black dots” on T1 and T2 weighted imaging but not diagnostic
  • Cerebral angiography:  faint blush associated with a venous channel in the late arterial/early capillary phase




Siddiqui, Fazeel M., Simon V. Bekker, and Adnan I. Qureshi. “Neuroimaging Of Hemorrhage And Vascular Defects”. Neurotherapeutics 8.1 (2011): 28-38.

Uptodate.  “Arteriovenous malformations” and “Vascular malformations of the central nervous system.” Accessed 03/05/2016.



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