Multiphase multidetector-row CT reveals different patterns of hepatic portal venous gas and pneumobilia

Hepatic portal venous gas and pneumobilia (PB) are uncommon findings, indicating the accumulation of gas in the portal vein and its branches and in the biliary tree, respectively. Aims of this retrospective, descriptive study were to describe the computed tomographic (CT) features and visualization techniques of hepatic portal venous gas (HPVG) and PB in a group of small animal veterinary patients. The CT data of patients with HPVG and PB were retrospectively reviewed. Thin-section multiplanar reformatting and minimum intensity projection (MinIP) views were used to assess the acquired volume dataset. The CT features recorded were as follows: amount, aspect, distribution, and localization of the gas in the liver. Five patients were included (four dogs and one cat), two presenting HPVG and three with PB. Gas in HPVG presented a peripheral location, whereas in PB was characterized by a central location. The aspect of the gas was tubular in case of HPVG and mixed tubular and rounded in PB. An analogous number of animals between the two groups showed comparable amount (mild, moderate, and severe) and distribution (diffuse and focal). Thin-section CT can detect the presence of gas in the liver, and a combination of two-dimensional and thin-slab MinIP can differentiate between HPVG and PB in dogs and cats. The distinctive features are peripheral versus central location and tubular versus rounded aspect of the gas.