Cerebral venous sinus thrombosis CT

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Kalsang Dolma, M.B.B.S.[2] Sharmi Biswas, M.B.B.S

CT scans of brain findings are helpful to diagnose cerebral venous sinus thrombosis.

• Cerebral edema and venous infarction are commonly seen. ^[1]

• In unenhanced CT scan, hyperattenuating signal is found in occluded sinuses which is a classic finding of cerebral venous thrombosis, but only found in 25% of cases.
• In patients with dehydration, an elevated hematocrit level, or a subjacent subarachnoid hemorrhage or subdural hematoma, increased attenuation in the venous sinuses.

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For the detection of the thrombus itself, the most commonly used tests are computed tomography (CT) and magnetic resonance imaging (MRI), both using various types of radiocontrast to perform a venogram. Computed tomography, with radiocontrast in the venous phase (CT venography or CTV), has a detection rate that in some regards exceeds that of MRI. The test involves injection into a vein (usually in the arm) of a radioopaque substance, and time is allowed for the bloodstream to carry it to the cerebral veins – at which point the scan is performed. It has a sensitivity of 75-100% (it detects 75-100% of all clots present), and a specificity of 81-100% (it would be incorrectly positive in 0-19%). In the first two weeks, the “empty delta sign” may be observed (in later stages, this sign may disappear). To detect thrombus, CT and MRI are most commonly used. CT with radiocontrast in the venous phase (CT venography or CTV), is more efficacious in detecting thrombus than MRI.

Cerebral angiography may demonstrate smaller clots, which can be found as “corkscrew appearance”.

Contrast material is inserted directly into the dural sinus or cerebral vein via the internal jugular vein. Intraluminal thrombosis presents as a filling defect though there is a non-occlusive thrombus while complete non-filling defect in presence of an occlusive thrombus. Complete thrombosis may present as a ‘cupping appearance’. During direct cerebral venography, venous pressure can be measured to detect venous hypertension. In CVT , venous hypertension is evident due to the parenchymal change caused by the thrombosis.^[1][2]