Contrast extravasation on computed tomographic angiography mimicking a basilar artery aneurysm in angiogram-negative subarachnoid hemorrhage:  report of 2 cases.
BACKGROUND
Contrast extravasation on computed tomography angiography (CTA) is becoming more common, with increasing use of CTA for myriad intracranial vascular pathologies. This article describes the first 2 documented cases of contrast extravasation from a nonaneurysmal basilar artery source seen on CTA and discusses possible pathophysiologic mechanisms.


METHODS
We present 2 cases of diffuse atraumatic subarachnoid hemorrhage in which the CTA showed an abnormality in association with the basilar artery highly suggestive of a ruptured aneurysm. Follow-up digital subtraction angiography, however, was completely negative. Subsequent repeat digital subtraction angiography failed to reveal a vascular lesion. Both patients were treated for complications associated with SAH, but given the negative digital subtraction angiography, no intervention was performed.


CONCLUSIONS
Because of the frequent use of CTA, contrast extravasation is an increasingly common observation. Physicians should be aware that basilar artery extravasation can mimic the appearance of an aneurysm.
Department of Neurosurgery, North Shore Hospital, Manhasset, New York, USA.
Nate D
ND
Stetson
John
J
Pile-Spellman
Jonathan L
JL
Brisman
D015901:Angiography, Digital Subtraction; D006801:Humans; D002532:Intracranial Aneurysm / Q000150:complications / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D013345:Subarachnoid Hemorrhage / Q000150:complications / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed