Pancreatitis was diagnosed on admission, but despite standard therapy, there was limited improvement with worsening abdominal pain.  

There is focal hypodensity within the portal vein on the arterial phase imaging which could be misinterpreted as portal vein thrombus. The subsequent portal venous phase CT shows normal enhancement of the portal vein.

The apparent portal vein thrombus is the result of admixing of contrast-enhanced blood from the splenic vein and non-contrast-enhanced blood from the SMV causing a reduction in attenuation.