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Attenuated Vein Sign Sensitive for Cerebral Deep Venous Thrombosis Diagnosis

January 1, 2010
Written by: , Filed in: Diagnostic Imaging
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The objective of a recent study was to determine the sensitivity and specificity of non-contrast-enhanced CT (NCCT) in the evaluation of cerebral DVT and venous sinus thrombosis (SVT).

The study has shown that non-contrast CT is more sensitive and specific in assessing for cerebral deep vein thrombosis (DVT) than for cerebral venous sinus thrombosis. Sensitivity for venous sinus thrombosis is particularly low.

Design
Retrospective study.

Participants
The study included eight patients with cerebral DVT and 25 patients with cerebral SVT. In addition, 36 consecutive patients with clinical symptoms compatible with DVT or SVT, but who did not have thrombosis, were evaluated as controls.

Methodology
All patients had undergone NCCT and either multidetector CT venogram or venous MRA combined with gradient echo T2. NCCT images were evaluated for hyperattenuated sinuses (“cord sign”), including superior sagittal sinus, inferior sagittal sinus, right and left transverse sinus, and right and left sigmoid sinus.

Hyperattenuated deep cerebral veins (“attenuated vein sign”) included straight sinus, right and left internal cerebral veins, vein of Galen, right and left basal veins of Rosenthal, and thalamostriate veins. Confidence in diagnosis of thrombosis was recorded on a scale of 1 to 5, with 1 being absolutely certain and 5 being uncertain.

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Results
Three neuroradiologists read studies on 69 subjects for a total of 207 readings. There were 28 false-negative and 5 false-positive diagnoses of patients with SVT. There was only one patient with a false-positive diagnosis of DVT (in a patient who had SVT) and no false-negatives. The cord sign (for SVT) was 64.6% sensitive and 97.2% specific, whereas the attenuated vein sign (for DVT) was 100% sensitive and 99.4% specific.

If one looks at individual structures, sensitivity drops to 33.9% and 93.5% respectively, and specificity was 99.4% and 95%, respectively. In general, mean diagnostic confidence of the observers was near absolutely certain (1.1) assessing for DVT on NCCT, but was more equivocal for SVT (3.7 to not very certain). Interobserver agreement for attenuated vein sign was 0.958, whereas it was 0.80 for the cord sign.

Conclusions
There is a high sensitivity and specificity of the attenuated vein sign for diagnosis of DVT, but not for SVT. Therefore, if one of these signs is present, further evaluation with venous CTA is necessary. The absence of attenuated vein sign makes DVT unlikely, but the absence of a cord sign does not exclude SVT.

Reviewer’s Comments This was a well-performed and clinically relevant study. Despite the low false-positive rate of DVT, the low prevalence of this diagnosis will still result in a relatively low positive predictive value. The study highlights the fact that NCCT is rather insensitive for SVT, and clinical suspicion should always be high in patients with risk factors.

Author: Yaron Lebovitz, MD

Reference:
Linn J, Pfefferkorn T, et al. Noncontrast CT in Deep Cerebral Venous Thrombosis and Sinus Thrombosis: Comparison of Its Diagnostic Value for Both Entities. AJNR Am J Neuroradiol; 2009;30 (April): 728-735.

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