DOI:10.2214/AJR.07.3867
AJR 2008; 191:W76
© American Roentgen Ray Society
Cause of False-Positive When Using Arterialization of Cerebral Veins as a Diagnostic Feature of Dural Arteriovenous Fistula
Graeme C. Simpson and
Evelyn Teasdale
Institute of Neurological Sciences Southern General Hospital Glasgow,
Scotland, United Kingdom
WEB—This is a Web exclusive article.
Meckel et al. [1] have
previously described the arterialization of cerebral veins on MDCT as a sign
of dural arteriovenous fistula (DAVF). They conclude that although
arterialization of cerebral veins is a significant CT finding of this
important condition, they cannot determine the sensitivity and specificity of
this sign. As the authors recommend, we actively look for this sign in
patients with nonspecific symptoms that could be related to DAVF. We report a
recent case of a patient who showed this sign as the result of an alternative
mechanism.
A 56-year-old woman presented with sudden-onset headache and confusion.
Initial unenhanced CT showed hemorrhage within the third ventricle with no
evidence of subarachnoid blood. The patient was transferred to our tertiary
neurosciences unit for further management. MDCT angiography was performed
using a Brilliance 64 scanner (Philips Healthcare) with 60 mL of iobitridol
(Xenetix 350, Guerbet) contrast material delivered at 5 mL/s using bolus
tracking to initiate acquisition. CT angiography (CTA) showed increased
density of the left transverse sinus with no other intracranial abnormality
(Fig. 1A). This raised the
possibility of arterialization of the venous blood as described by Meckel et
al. [1]. Subsequently,
Hounsfield values of the left transverse sinus and left intracranial internal
carotid artery were assessed. We found that the Hounsfield value of the venous
blood exceeded that of the arterial system
(Fig. 1B). This, therefore,
excluded the possibility that contrast material was passing from the
extracranial arterial system through a fistula into the venous system because
the degree of enhancement would then be the same or lower.
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Fig. 1A —56-year-old woman with sudden-onset headache and confusion.
CT angiography image shows apparent arterialization of left transverse sinus
with high-attenuation contrast relative to right transverse sinus.
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We also noted that the posterior extracranial venous system was prominent,
with intensity greater than that of the arterial system
(Fig. 1C). We concluded that
the apparent arterialization of the transverse sinus was a result of venous
system contrast reflux, perhaps caused by a Valsalva maneuver or
breath-holding during acquisition. Because the patient had had an
intraventricular bleed when undergoing CTA, which resulted in normal findings,
intraarterial digital subtraction angiography was performed. These findings
were also normal.
We therefore recommend measuring the intensity of the venous system
relative to the arterial system, as well as assessing any visualized
extracranial veins, in patients with apparent arterialization of cerebral
veins to prevent false identification of DAVF.
References
- Meckel S, Lovblad KO, Abdo G, et al. Arterialization of cerebral
veins on dynamic MDCT angiography: a possible sign of a dural arteriovenous
fistula. AJR 2005;184
: 1313-1316[Abstract/Free Full Text]
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S. Meckel and S. G. Wetzel
Reply
Am. J. Roentgenol.,
August 1, 2008;
191(2):
W77 - W77.
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