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Imaging of Pediatric Liver Transplant Complications Jeevesh Kapur, Vidyadhar Mali

Dept Diagnostic Imaging, Dept of Pediatric Surgery National University Hospital, Singapore

Purpose To evaluate the role of various imaging modalities in assessment of possible complications of Pediatric Liver Transplant and their impact on further management of these complications.

Method and Results All pediatric patients who were referred to the department of Diagnostic Imaging for assessement of various immediate and late complications of living related liver transplants in children were retrospectively assessed. We cam across a large varied range of complications, including hematomas, post operative collections, abscesses, hepatic artery occlusion, liver infarcts, portal vein thromobosis, intrahepatic biliary strictures, PTLD and EBV induced tumors.

Heterogenous collections with internal septations and loculations, usually along the cut surface of the l iver. Other common location being subdiaphragmatic.

PERIHEPATIC COLLECTION

US: Shows large heterogenous collection adjacent to the lateral liver border, in the right subdiaphragmatic region

HEPATIC ARTERY STENOSIS

Ultrasound may give an early indication of hepatic artery stenosis with high flow velocities, which can be confirmed with CT studies.

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References

US and CT show high velcoties of main hepatic artery on ultrasound and CT confirms the focal narrowing of the main hepatic artery at the porta hepatis.

TRANSPLANT LIVER ABSCESS

Avascular hypoechoic mass with thick irregular walls and areas central necrosis that do not show any vascularity

CEUS: Contrast enhanced ultrasound shows a necrotic lesion with non-enhancing centre and thick enhancing margins, consistent with an abscess

PORTAL VEIN THROMBOSIS

Portal vein thrombosis is an important diagnosis which requires immediate attention and may lead to re-exploration. US can typically show a filling defect or loss of normal flow within the main portal vein

US: Two different patients showing filling defects in the main portal vein, consistent with portal vein thrombosis.

Conclusion

Radiology plays a major role in the diagnosis, follow up and management of liver transplant complications. Imaging modalities such as Ultrasound is usually the first investigation performed, with CT or MRI usually performed as a follow up or to confirm the diagnosis. A spectrum of various complications is presented, along with their imaging features.

HEPATIC INFARCTS

Hepatic infarcts appear as areas of low echogenicity on US and low density on CT studies. They typically do not show any internal vascularity or enhancement. Some of the infarcts may show rim calcifications

US and CT: us shows hypoechoic areas in the periphery of the transplanted liver, with no vascularity on Doppler. CT shows hypodense areas, with rim calcifications.

PERI-TRANSPLANT BLEED

CEUS: Routine and contrast ultrasound shows an enlarging heterogenous collection along the cust surface, which shows areas of enhancement, suggesting active bleed.

BILIARY STRICTURES

US and MRI: US shows long segment dilatation of one of the intrahepatic biliary ducts. MRI shows a dilated duct with a stricture at its medial aspect.

EBV RELATED TUMORS

US: Multiple hypoechoic and heterogenous lesions in the liver and spleen, confirmed on histology to be EBV related smooth muscle tumors.

CHOLANGITIS

US: Shows diffuse increased periportal echogenicity and thickening of the portal triad. The biliary duct wall appears thickened, consistent with cholangitis

Heterogenous collection solid and cystic areas, may appear to increase on susbsequent imaging which would represent active bleeding or ooze from the surgery site