-2 :: Topic - 2718 :: :: ::
Medical Image Database, Atlas, and Teaching File
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Portal Vein Thrombosis - Differential Diagnosis:

1.   Portal hypertension
a.   Cirrhosis is the most common cause in the West;
b.   Schistosomiasis is the most common cause world wide
2.   Malignancy
a.   Primary or secondary hepatic malignancy
b.   Gastric carcinoma
c.   Pancreatic carcinoma
d.   Cholangiocarcinoma
3.   Portal or mesenteric pyelophlebitis, associated with appendicitis or diverticulitis
4.   Hypercoaguable states
5.   Iatrogenic causes
a.   Upper abdominal surgery
b.   Endoscopic sclerotherapy
c.   Hepatic transplantation
6.   Inflammatory disorders
a.   Crohn's disease
b.   Ulcerative colitis
c.   Pancreatitis

Alcoholic liver disease is comprised of three interrelated conditions. Alcoholic hepatitis consists of bouts of acute hepatic necrosis following drinking binges. These episodes are usually superimposed on fatty infiltration and cirrhosis of the liver, which are the result of chronic hepatocellular injury.

Portal vein thrombosis is caused by a number of intra and extra hepatic factors, some of which are outlined above. Cirrhosis, with resultant portal hypertension and venous stasis, is the most common cause in the developed world.

In alcoholic liver disease, the liver is generally enlarged, except in advanced cirrhosis. Fatty infiltration may be focal or diffuse and manifests itself as increased hepatic echogenicity on ultrasound and decreased attenuation on CT. With progressive sclerosis, the liver surface appears nodular. Hepatocellular carcinoma occurs at a greater rate than in the general population and may be difficult to detect because of architectural distortion of the liver. Portal hypertension causes ascites, splenomegaly and the formation of varices. Hepatofugal flow may be detected in the portal or splenic veins. Variceal bleeding is a major cause of mortality. While varices are also seen in splenic vein thrombosis, recanalization of the umbilical vein is specific for portal hypertension.

On CT, portal vein thrombosis appears as low attenuation within the vessel lumen with enhancement at the borders of the vessel. Heterogeneous attenuation and atrophy occur in sub served hepatic segments. On MR, thrombus has a variable appearance depending on its age. Failure to visualize the portal vein is also indicative of thrombosis. Both black blood and gadolinium-enhanced images are useful. Failure to document flow, hepatofugal flow, and non-visualization of the portal vein are indicative of portal vein thrombosis on ultrasound.