CT cerebral venography (protocol)

CT cerebral venography is a rapid technique which provides an accurate detailed depiction of the cerebral venous system.

Indications

Rapid and reliable diagnosis of cerebral venous thrombosis.

Contraindications

General CT contraindications such as pregnancy, claustrophobia, etc.

Technique

Actual procedure will vary depending on institutional protocol/guidelines but below is a typical description:⁵

• peripheral venous access (18-20G) in an antecubital vein
• nonionic contrast material is injected at 4-5 mL/s for a total of 100-120 mL with a 45-second prescanning delay
• a helical scan is performed by scanning caudally from the calvarial vertex to C1

Data acquisition and analysis

• images are analyzed on a dedicated workstation
• proper evaluation of the dural sinuses indicates proper inspection ofthe axial thin-section contrast-enhanced source images of a helical CT scan
• two-dimensional (2D) & three-dimensional (3D) multi-planar images, as well as rendering techniques such as maximum intensity projection (MIP),surface shaded displays (SSD) and volume rendering (VR) in a sagittal, coronal, and oblique planes
• an essential step in CT venography is removal of bone from the images, by graded subtraction

Findings

Venous sinus abnormalities

• venous sinus thrombosis
• recanalization, the sinus shows an irregular appearance with multiple intrasinus channels and dural collateral vessels
• sinus stenosis or occlusion secondary to tumor invasion e.g. meningioma
• vascular malformation e.g.  AVM, dural arteriovenous fistula or developmental venous anomaly
• idiopathic intracranial hypertension:bilateral stenoses of the transverse sinuses, without definitive evidence of current or prior thrombosis 

Parenchymal abnormalities

• cerebral parenchymal abnormalities such as hemorrhagic infarction

Normal variations

• sinus hypoplasia and aplasia
• arachnoid granulations
• sinus duplication or fenestration
• variant  anatomy of the sinuses e.g. occipital sinus or persistent falcine sinus