Correct answer to Q1 is:  Inhomogeneity in CT attenuation in the right liver lobe due to infarction or thrombosis or hematoma

The CT scan showed no free air or leakage, but inhomogeneity in CT attenuation in the right liver lobe. Most likely representing infarction, thrombus or hematoma. Therefore, the patient was further examined with abdominal ultrasound to evaluate the vessels.

Correct answer to Q2 is: Focal infarction or thrombosis in the right hepatic vein

There is a long hypoechoic area in segments 7/8 compared to the rest of the liver parenchyma. On colour Doppler no signal was obtained from the right liver vein. The hypoechoic area most likely represents an infarction due to acute thrombosis. It is less likely to be a hematoma, as postoperative hematomas are usually located at the surface or just below the liver capsule. Focal fatty sparing is often located adjacent to the gallbladder. Lastly biloma appears like a cyst, which is anechoic, has posterior acoustic enhancement and often a round shape.

Correct answer to Q3 is: Focal liver infarction and mural thrombosis in the IVC

Discussion:

The contrast enhanced ultrasound images (CEUS) revealed a focal infarction (contrast defect) in the liver and a mural thrombosis in the IVC and the right liver vein. The mural thrombosis becomes apparent as a filling defect in the IVC, which remained in the late phase.

Ultrasound is a very important tool in evaluating the liver for post-transplantation complications. Many complications can occur soon after transplantation, incl. vascular, biliary and infectious complications. Hepatic artery thrombosis is the most significant complication and is often associated with graft failure (1). If the graft survives, biliary ischemia may, in turn, lead to a non-anastomotic biliary stricture or leak resulting in a biloma. Thrombosis can also occur in other vessels such as the portal and hepatic veins leading to partial infarction. In addition, most patients are treated with immunosuppressive drugs that make the graft prone to infections and abscess. Finally, bleeding and leakage from the anastomoses are also serious complications (1).

Ultrasound provides a tool to evaluate the liver parenchyma, biliary tree, and vessels for abnormalities. Colour and Spectral Doppler enable us to check the blood supplies to the liver graft by measuring RI-indices and vascular acceleration, without any radiation and exposure to CT contrast agents (2). Furthermore, it may be performed in the intensive care unit.

CEUS becomes a very important tool, in cases like ours, where the patient does not tolerate CT contrast agent. With CEUS, we can evaluate the enhancement of the liver parenchyma, the vessel patency and the complications of the graft, including arterial and venous stenosis, infarction and necrosis, abscess, hematomas, and malignancy (2).

In conclusion, ultrasound and CEUS are important tools in evaluating post-transplantation complications including vascular and infectious complications.

Conflicts of interest

“The authors declare no conflict of interest.”

References

1. Singh AK, Nachiappan AC. Postoperative imaging in liver transplantation: what radiologists should know. Radiographics. 2010 Mar;30(2):339-51.
2. Girometti R, Como G, Bazzocchi M, Zuiani C. Post-operative imaging in liver transplantation: state-of-the-art and future perspectives. World J Gastroenterol. 2014 May 28;20(20):6180-200