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Portal Vein Occlusion


KEY FACTS

Terminology

  • Acute, chronic, or neoplastic occlusion of portal vein (PV) due to thrombosis, thrombophlebitis, or tumor invasion

  • Chronic PV occlusion with numerous periportal collaterals is referred to as "cavernous transformation"

Imaging

  • Color Doppler US initially : Accurate and cost effective

    • Periportal collaterals may be mistaken for patent PV

    • Tumor vessels may be evident within PV mass

  • Multiphasic, multiplanar enhanced CT or MR

  • Contrast-enhanced CT of acute PV thrombosis

  • Arterial phase (25-40 seconds post bolus injection)

    • High attenuation/intensity within involved hepatic lobe or segment due to arterioportal shunting

    • Transient hepatic attenuation difference

  • Venous phase (60-70 seconds post bolus injection)

    • Equilibration of hepatic contrast enhancement

    • Visualization of low-density thrombus

  • CECT of chronic PV thrombosis

    • Numerous periportal collateral veins along usual course of PV

    • Peripancreatic and gallbladder wall varices are common

    • Nonvisualization of PV &/or splenic vein

  • CECT of PV tumor invasion

    • Lumen of vein may be expanded by thrombus

    • Variable degree of contrast enhancement of intraluminal tumor thrombus

    • Contiguity of parenchymal tumor with PV thrombus

Pathology

  • Most often associated with hepatic cirrhosis and pancreatitis

  • Primary PV thrombosis may be 1st sign of hypercoagulable (prothrombotic) condition

Clinical Issues

  • PV tumor invasion (usually from hepatocellular carcinoma) is associated with poor clinical outcome

  • Primary PV thrombosis may mimic cirrhosis

    • Results in dysmorphic and malfunctioning liver

    • Often results from prothrombotic condition

  • Thrombosis or fibrosis of extrahepatic PV may complicate or preclude liver transplantation

  • Treatment: Anticoagulation for acute bland thrombosis or hypercoagulable condition

    • Add antibiotics for septic thrombophlebitis

Axial CECT in a 55-year-old man with hepatitis B who presented for routine CT screening to rule out hepatocellular carcinoma (HCC) shows cavernous transformation of the portal vein with numerous small collateral veins
in the porta hepatis and hepatoduodenal ligament. The main portal vein cannot be identified.

Axial CECT of a 55-year-old man with cirrhosis and bleeding gastric varices shows "bland" (not malignant) thrombosis of the portal vein
, a cirrhotic liver, and huge upper abdominal varices
.

Longitudinal grayscale ultrasound obtained through the porta hepatis in a 51-year-old woman presenting with vague right upper quadrant pain and a recent elevation of liver function tests reveals no apparent abnormalities of the portal vein
.

Longitudinal power Doppler ultrasound obtained in the same patient in the same field of view reveals an acute thrombosis
of the portal vein with a complete absence of flow, which was undetectable with grayscale sonography alone.

TERMINOLOGY

Synonyms

  • Portal vein (PV) thrombosis

Definitions

  • Acute, chronic, or neoplastic occlusion of PV due to thrombosis or tumor invasion

  • Chronic PV occlusion with numerous periportal collaterals is referred to as cavernous transformation

IMAGING

General Features

  • Best diagnostic clue

    • Low-attenuation thrombus in PV on CECT

    • On MR and power Doppler: Absence of blood flow or flow void in PV

      • –

        May be caused or simulated by slow flow in portal hypertension

      • –

        Nonvisualization of PV (chronic occlusion)

      • –

        Cavernous transformation of PV (collateralization in porta hepatis)

  • Location

    • May involve any portion of intra- or extrahepatic PV

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