- 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.
CAVERNOUS HEMANGIOMAS / MALFORMATIONS:
- 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”)
DEVELOPMENTAL VENOUS ANOMALY:
- 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
- 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.