Periportal Halo

Contrast-enhanced CT image (coronal reformat) shows circumferential zone of low attenuation around the portal vein branches. Seen en face (arrows) and in profile (arrowheads).

Features of Periportal Halo

• Circumferential (differentiating feature from dilated bile ducts)
  
• Low attenuation (could represent fluid, lymph, or blood)
• Peripheral portal veins

Differential Diagnosis

• Liver trauma (blood tracks in periportal space)
• Edema (CHF, burn, volume resuscitation)
• Hepatitis
• Lymphatic obstruction (obstructing portal lymph nodes or malignancy)

It may be the most prominent sign of malignancy! Look carefully for lymph nodes in the portal region and lesser omentum before signing it out as due to other more benign causes.

Our patient is a young man with toxic hepatitis. Periportal halo is due to his hepatitis.

References:
Lawson TL, et al. Periportal halo: a CT sign of liver disease. Abdom Imaging 1993;18:42.