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Spectrum of Imaging Findings After Pediatric Liver Transplantation: Part 2, Posttransplantation Complications

¹ Department of Pediatrics, Leopold-Franzens University, Anichstra. 35, Innsbruck A-6020, Austria.
² Department of Radiology, Leopold-Franzens University, Innsbruck A-6020, Austria.
³ Department of Surgery, Leopold-Franzens University, Innsbruck A-6020, Austria.

Received December 16, 2002; accepted after revision February 14, 2003.

 
Address correspondence to K. M. Unsinn.

Introduction

Top Introduction Transplantation Procedures Imaging Modalities Imaged Abnormalities Conclusion References

 
Liver transplantation has emerged as an effective treatment for liver failure for a variety of diseases in pediatric patients. Transplantation procedures performed in children include whole cadaveric pediatric organ grafts as well as segmental grafts after splitting an adult cadaveric liver or after splitting an adult living related donor liver using segments II and III or segments II, III, and IV [1, 2].

Graft survival depends on the immediate diagnosis of and therapy for specific graft-related complications [3, 4], among other factors. Complications of the anastomoses are particularly common, mainly stenosis or thrombosis of the common hepatic artery, portal vein, or hepatic veins as well as stenosis or leakage of the bile duct with cholestasis, cholangitis, biliary stones, and biloma [5–8]. Many other complications can occur, such as perihepatic fluid collection with hematoma, seroma, abscess, graft rejection, or posttransplantation lymphoproliferative disorder. Rapid diagnosis and treatment can result in complete recovery with no deleterious effect on long-term outcome [6, 7].

We use various imaging modalities to show typical examples of vascular and biliary complications that may result from liver transplantation in children.

Transplantation Procedures

Top Introduction Transplantation Procedures Imaging Modalities Imaged Abnormalities Conclusion References

 
Two procedures are frequently used to perform liver transplantation in children.

Orthotopic Liver Transplantation with Whole Cadaveric Pediatric Organ Graft
Orthotopic liver transplantation using a whole cadaveric donor liver is usually performed with an end-to-end anastomosis to the inferior vena cava, portal vein, and common hepatic artery. In children without bile duct abnormalities, an end-to-end anastomosis of the common hepatic duct can be performed, but in children with bile duct anomalies, a hepaticojejunostomy is required [7].

Orthotopic Liver Transplantation with Segmental Organ Graft
Living related donor partial adult organ grafts and split cadaveric liver grafts are becoming more important surgical possibilities for reducing mortality in children on the waiting list [1, 2] because of the increasing number of liver transplantations and the limited availability of pediatric cadaveric donor livers. The left lateral segments (II and III) and, in rare instances, the left hepatic lobe (segments II, III and IV) are harvested as donor organs. The recipient's inferior vena cava is always preserved, and the donor's left and middle hepatic veins are sealed in a large incision of the inferior vena cava to optimize hepatic venous outflow, which is not done in whole liver transplantation. Portal, arterial, and venous hepatic end-to-end anastomoses are attempted. If, however, the recipient's hepatic artery is too small or too short, arterial reconstruction is performed using a donor's conduit from the infrarenal aorta. Biliary anastomosis is performed between the donor's left lateral hepatic duct and a jejunal loop in the recipient.

Imaging Modalities

Top Introduction Transplantation Procedures Imaging Modalities Imaged Abnormalities Conclusion References

 
Various imaging modalities are used to detect acute and chronic posttransplantation complications. Sonography and color Doppler sonography are preferred for serial follow-up and for detection of vascular, biliary, and parenchymal complications. Sonography is limited by the presence of intestinal gas, especially at the liver hilum, which is the most important region of interest because of the arterial, portal vein, and biliary anastomoses. Sonography is supplemented by contrast-enhanced single-detector helical CT, which has the advantage of displaying the whole liver parenchymal, vascular, and biliary structures without being affected by intestinal gas. Also, contrast-enhanced multidetector CT enables three-dimensional reconstruction of the vascular anatomy in relation to neighboring anatomic structures. MRI and MR cholangiopancreatography are complementary examinations for detecting biliary complications. Angiography is used to confirm vascular complications and sometimes to guide immediate endovascular therapy. Localized fluid collections such as biloma, seroma, hematoma, and abscess are treated percutaneously with other imaging-guided interventions. Bile duct obstruction is treated with percutaneous transhepatic cholangiography, with or without drainage.

Imaged Abnormalities

Top Introduction Transplantation Procedures Imaging Modalities Imaged Abnormalities Conclusion References

 
Typical complications after liver transplantation in children affect the vascular and biliary system and include other transplantation-associated complications.

Vascular Complications
Hepatic artery stenosis (Fig. 1) and thrombosis (Fig. 2A, 2B) are major complications resulting in infarction or necrosis of the liver parenchyma and ischemic cholangiopathy. Parenchymal necrosis presents as irregular hypoechogenic or hypodense lesions in the subcapsular region of the liver (Fig. 3). Portal vein complications include stenosis or thrombosis of the portal vein (Figs. 4A, 4B, 5A, 5B, 6). Risk factors include preexisting portosystemic shunts with ensuing decreased portal vein flow (Fig. 7A, 7B) or graft interposition. Local thrombolysis of a portal vein thrombosis or balloon dilatation with stent implantation (Fig. 8A, 8B) can be performed by a direct transhepatic access. Thrombosis (Fig. 4A) and stenosis of the hepatic vein are other potential vascular complications.

View larger version (174K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 1. —Celiac angiogram obtained in 3-year-old girl 6 weeks after orthotopic whole liver transplantation necessitated by liver cirrhosis in Alagille syndrome (sixth postoperative week). Long segment stenosis of common hepatic artery (between arrowheads) developed after end-to-end anastomosis.

View larger version (168K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 2A. —2-year-old boy 3 weeks after orthotopic whole liver transplantation necessitated by liver cirrhosis in Alagille syndrome. Arterial revascularization was achieved via conduit from abdominal aorta and donor's common hepatic artery. Selective arteriogram shows acute thrombosis of proximal common hepatic artery conduit (arrow).

View larger version (143K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 2B. —2-year-old boy 3 weeks after orthotopic whole liver transplantation necessitated by liver cirrhosis in Alagille syndrome. Arterial revascularization was achieved via conduit from abdominal aorta and donor's common hepatic artery. Control selective arteriogram obtained after local arterial thrombolysis shows recanalization with patent arterial conduit, relative narrowing of anastomosis of arterial conduit and donor's common hepatic artery (arrow), ligated cystic artery stump (black arrowhead), residual filling defect of right hepatic artery (white arrowhead), and normal opacification of intraparenchymal arteries.

View larger version (179K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 3. —High-resolution sonogram (longitudinal section) of liver parenchyma obtained in 4-year-old girl 4 weeks after orthotopic whole liver transplantation necessitated by Crigler-Najjar syndrome. Hepatic artery thrombosis (not shown) causes concomitant peripheral subcapsular hypoechoic areas consistent with focal parenchymal necrosis (arrowheads).

View larger version (168K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 4A. —Single-detector helical scans of 17-year-old boy obtained 5 weeks after whole liver transplantation necessitated by liver cirrhosis in cystic fibrosis. Contrast-enhanced scan shows hepatic vein thrombosis (arrow) in segment VII of liver with ensuing decreased contrast enhancement.

View larger version (149K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 4B. —Single-detector helical scans of 17-year-old boy obtained 5 weeks after whole liver transplantation necessitated by liver cirrhosis in cystic fibrosis. Contrast-enhanced scan shows acute complete thrombotic occlusion of splenic vein (arrowhead) with dome-shaped thrombus (arrow) projecting into proximal portal vein. Curvilinear structure in wall of portal vein is stapled portal vein anastomosis.

View larger version (172K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 5A. —13-year-old boy 3 weeks after orthotopic whole liver transplantation necessitated by liver cirrhosis in cystic fibrosis. Contrast-enhanced single-detector helical CT scan shows acute incomplete thrombosis of main stem of portal vein (arrow) with associated periportal intrahepatic edema, ascites, and central bile duct dilatation.

View larger version (182K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 5B. —13-year-old boy 3 weeks after orthotopic whole liver transplantation necessitated by liver cirrhosis in cystic fibrosis. High-resolution sonogram of intrahepatic portal vein also shows small embolized thrombus (arrow) of intrahepatic portal vein originating from thrombosis of extrahepatic portal vein.

View larger version (193K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 6. —Indirect portogram obtained 9 years after selective contrast injection in superior mesenteric artery in 10-year-old boy after orthotopic whole liver transplantation necessitated by biliary atresia. Image shows cavernous transformation of portal vein (between arrows) caused by long-standing thrombotic occlusion with extensive collateral venous network in upper abdomen.

View larger version (192K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 7A. —14-year-old boy 3 weeks after orthotopic whole cadaveric liver transplantation necessitated by liver cirrhosis in cystic fibrosis with thrombotic occlusion of portal vein and unsuccessful trial of systemic thrombolysis. Direct portogram shows complete thrombotic occlusion of portal vein and collateralization via preexisting paragastric varices.

View larger version (164K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 7B. —14-year-old boy 3 weeks after orthotopic whole cadaveric liver transplantation necessitated by liver cirrhosis in cystic fibrosis with thrombotic occlusion of portal vein and unsuccessful trial of systemic thrombolysis. Direct follow-up portogram obtained after local thrombolysis using transhepatic approach to portal vein reveals complete resolution of thrombus and patent portal vein. Paragastric varices were occluded by coils (arrows) to increase portal blood flow and increase efficiency of thrombolytic therapy.

View larger version (136K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 8A. —2-year-old girl 3 years after segmental liver transplantation necessitated by extrahepatic biliary atresia. Indirect splenoportogram shows stenosis (arrow) of extrahepatic portal vein in vicinity of venous anastomosis with resulting portal hypertension and splenomegaly.

View larger version (142K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 8B. —2-year-old girl 3 years after segmental liver transplantation necessitated by extrahepatic biliary atresia. Direct portogram shows good results and complete resolution of stenosis after successful percutaneous transluminal angioplasty and stent implantation via transhepatic approach to portal vein.

Biliary Complications
Biliary complications manifest as leakage or stenosis of the biliary anastomosis with ensuing biloma and bile duct dilatation (Fig. 9), cholangitis, and stone formation (Fig. 10). The main risk factor for biliary stenosis is common hepatic artery insufficiency.

View larger version (145K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 9. —5-year-old girl 19 months after orthotopic whole liver transplantation necessitated by liver cirrhosis in Crigler-Najjar syndrome. Contrast-enhanced single-detector helical CT scan reveals dilated intrahepatic bile ducts caused by stenosis of hepaticojejunostomy (not shown).

View larger version (167K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 10. —5-year-old boy 4 years after orthotopic whole liver transplantation and hepaticojejunostomy necessitated by liver cirrhosis in Alagille syndrome. MR cholangiopancreatogram shows poststenotic dilatation of left hepatic duct (single arrowhead) and signal void area in proximal left hepatic duct (arrow), representing stone formation. Fluid is seen in stomach (asterisk) and in anastomosed jejunal loop (double arrowhead).

Other Transplantation-Associated Complications
Various localized fluid collections are observed after liver transplantation in children, including hematoma (Fig. 11), seroma (Fig. 12), ascites, and abscess. In most cases, these regress in size without treatment, but sometimes percutaneous diagnostic aspiration or therapeutic drainage is necessary. Other abnormalities may include perivascular edema (Fig. 12) caused by lymphatic obstruction and fatty liver degeneration. Posttransplantation lymphoproliferative disorder is a serious complication of liver transplantation and manifests either with lymphadenopathy, complex portal mass, or extranodal involvement of the gastrointestinal tract [9]. Hepatic graft rejection remains an important cause of graft loss. Rejection is not indicated by any specific imaging findings. Imaging modalities help in ruling out other abnormalities, but diagnosis can be established only histologically by percutaneous liver biopsy [10].

View larger version (177K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 11. —6-year-old boy 15 days after orthotopic whole liver transplantation necessitated by liver cirrhosis in cystic fibrosis. Sonogram of liver (longitudinal section) shows perihepatic hematoma (arrows).

View larger version (144K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 12. —Contrast-enhanced single-detector helical CT scan of 4-month-old male infant obtained 3 weeks after segmental liver transplantation (segments II and III) necessitated by congenital hepatitis (Aagenaes syndrome). Note postoperative seroma (asterisk) adjacent to parenchymal resection site of graft (marked by high-density line representing staples), portal vein (arrow), common hepatic artery (white arrowhead), and perivascular edema (black arrowheads).

Conclusion

Top Introduction Transplantation Procedures Imaging Modalities Imaged Abnormalities Conclusion References

 
Whole liver and segmental living related donor liver graft are the two most frequent liver transplantation procedures performed in children. Liver graft survival is related to the immediate diagnosis of and therapy for posttransplantation complications. The radiologist must be familiar with the spectrum of imaging findings after liver transplantation in children with regard to postoperative anatomy and complications.

References

Top Introduction Transplantation Procedures Imaging Modalities Imaged Abnormalities Conclusion References

 

1. Broelsch CE, Whitington PF, Emond JC, et al. Liver transplantation in children from living related donors: surgical techniques and results. Ann Surg 1991;214:428 –439[Medline]
2. Broelsch CE, Emond JC, Whitington PF, Thistlethwaite JR, Baker AL, Lichtor JL. Application of reduced-size liver transplants as split grafts, auxiliary orthotopic grafts, and living related segmental transplants. Ann Surg 1990;212:368 –377[Medline]
3. Ametani F, Itoh K, Shibata T, Maetani Y, Tanaka K, Konishi J. Spectrum of CT findings in pediatric patients after partial liver transplantation. RadioGraphics2001; 21:53 –63[Abstract/Free Full Text]
4. Pilleul F, Guibaud L, Dugougeat F, Lachaud A, Pracros J. MR cholangiography in biliary complications after liver transplantation in children [in French]. J Radiol2000; 81:793 –798[Medline]
5. De Gaetano AM, Cotroneo AR, Maresca G, et al. Color Doppler sonography in the diagnosis and monitoring of arterial complications after liver transplantation. J Clin Ultrasound2000; 28:373 –380[Medline]
6. Garcia-Criado A, Gilabert R, Nicolau C, et al. Early detection of hepatic artery thrombosis after liver transplantation by Doppler ultrasonography: prognostic implications. J Ultrasound Med 2001;20:51 –58[Abstract]
7. Fulcher AS, Turner MA. Orthotopic liver transplantation: evaluation with MR cholangiography. Radiology1990; 211:715 –722
8. Funaki B, Rosenblum JD, Leef JA, et al. Percutaneous treatment of portal vein stenosis in children and adolescents with segmental hepatic transplants: long-term results. Radiology2000; 215:147 –151[Abstract/Free Full Text]
9. Wu L, Rappaport DC, Hanbidge A, Merchant N, Shepherd FA, Greig PD. Lymphoproliferative disorders after liver transplantation: imaging features. Abdom Imaging2001; 26:200 –206[Medline]
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