Elsevier

Clinical Radiology

Volume 63, Issue 2, February 2008, Pages 136-145
Clinical Radiology

Review
Imaging evaluation of potential donors in living-donor liver transplantation

https://doi.org/10.1016/j.crad.2007.08.008Get rights and content

Liver transplants, originally obtained from deceased donors, can now be harvested from living donors as well. This technique, called living-donor liver transplantation (LDLT), provides an effective alternative means of liver transplantation and is a method of expanding the donor pool in light of the demand and supply imbalance for organ transplants. Imaging plays an important role in LDLT programmes by providing robust evaluation of potential donors to ensure that only anatomically suitable donors with no significant co-existing pathology are selected and that crucial information that allows detailed preoperative planning is available. Imaging evaluation helps to improve the outcome of LDLT for both donors and recipients, by improving the chances of graft survival and reducing the postoperative complication rate. In this review, we describe the history of LDLT and discuss in detail the application of imaging in donor assessment with emphasis on use of modern computed tomography (CT) and magnetic resonance imaging (MRI) techniques.

Introduction

Liver transplantation, introduced by Starzl et al.1 in 1968 is the recognized treatment of choice for patients suffering from end-stage liver disease. Over the years, surgical refinements, greater clinical expertise, and more effective immunosuppression have contributed greatly to the improved technical success of this operation. The growing clinical and political profile of liver transplantation has led to an expansion of the indications for transplantation, and as a consequence an escalating clinical demand for the procedure. Data from the USA, obtained from the United Network for Organ Sharing (UNOS), shows that from January 1 1988 to January 31 2007, a total of 82,157 liver transplants [78,882 (96%) deceased-donor liver, 3275 (4%) living-donor liver] were performed. In 2006 alone there were 6363 deceased and 288 living-donor liver transplants. Despite this, there remains an organ crisis due to a demand and supply imbalance with many more patients requiring liver transplants than there are available. UNOS data shows that a total of 17,429 patients are currently on the waiting list for liver transplantation, and of these patients, 2767 have been waiting for between 1–2 years and 4323 have been waiting 5 years or more. A significant proportion of patients die from their liver disease while on the waiting list. From 1 January 1995 to 31 January 2007, a total of 19,289 people died on the waiting list, while in 2006 alone, there were 1583 deaths.

Out of the need to expand the donor pool (cadaveric supply remaining stable at about 4000 a year) and alleviate this critical organ shortage, the innovative concept of living-donor liver transplantation (LDLT) as a surgical strategy was introduced. Since its inception over a decade ago, it has become a recognized and effective alternative means of liver transplantation for paediatric and adult patients. The number of LDLTs is increasing rapidly, as are the number of transplant centres offering the procedure. There were over four-times more living-donor operations performed in 2006 (288 cases, 4.3% of total liver transplants) than there were 10 years ago in 1996 (62 cases, 1.5% of total liver transplants). Sixty seven centres in the USA had performed at least one LDLT and 24 centres had performed more than 50 cases.

Imaging plays a central role in living-donor programmes by assessing whether potential donors are eligible candidates for donation based on anatomical considerations, and whether co-existing pathology is present. Alongside the evolution of LDLT, developments and refinements in imaging have created techniques that provide robust donor evaluation. In this review, we describe briefly the history of LDLT and discuss in detail the application of imaging in donor assessment with emphasis on use of modern CT and MRI techniques.

Section snippets

History of LDLT

The viability of LDLT as a concept is made possible because of the unique ability of the liver to regenerate following surgery and because its anatomical organization, as defined by Couinaud,2 into independently functioning segments (each with separate vascular inflow and outflow and biliary drainage) favours segmental transplantation. Its introduction as an innovative surgical option grew out of the need to reduce the paediatric waiting list mortality (around 20–30%) by providing appropriate

Hepatic steatosis

Imaging is performed to detect liver parenchymal abnormalities that may preclude living-donor transplantation. Although malignant liver lesions in a potential donor are a contraindication, benign lesions such as haemangioma, particularly if single and small size in size (≤2–3 cm), maybe transplanted safely and do not exclude liver donation.13 However, in the vast majority of cases, parenchymal imaging focuses mainly on detecting hepatic steatosis, which, if present in a significant quantity, can

Vascular anatomy

A comprehensive vascular road map facilitates detailed surgical planning and reduces the postoperative complication rate in both donor and recipient.42, 43 Conventional catheter angiography is the traditional standard of reference for vascular evaluation but has the drawback of being an invasive procedure. Rapid technological advances in cross-sectional imaging have led to non-invasive techniques, such as CT and MRI replacing conventional angiography for routine evaluation of hepatic vascular

Biliary tract anatomy

Anomalous biliary tract anatomy (present in 40% of the population Fig. 6) poses significant technical challenges for LDLT surgery. Postoperative biliary complications (incidence of 15–40% in recipients,56, 57 4–13% in donors58, 59) are the bane of LDLT largely due to the technical difficulties of performing biliary reconstruction on small calibre bile ducts and due to the propensity to severe postoperative bile leakage if even minor intrahepatic branches that cross the dissection line are

“All-in-one” imaging protocols

Donor evaluation is frequently a multi-technique imaging process. This set up is time-consuming and puts substantial demands on radiology resources. To simplify and shorten this diagnostic pathway and make it a more acceptable experience for donors, some centres have explored the possibility of performing donor evaluation as a single comprehensive imaging study.32, 33, 74, 75, 76 CT32, 33 and MRI74, 75, 76 have been assessed for their suitability in providing “all-in-one” imaging – providing

Conclusion

Alongside the evolution of LDLT, developments in imaging have created efficient CT and MR techniques that provide detailed donor evaluation. This facilitates appropriate donor selection and provides crucial preoperative information required for meticulous surgical planning. This process has traditionally involved a multimodality approach, but improvements in CT and MR technology have simplified this pathway into a single comprehensive imaging study (“all-in-one” imaging) that allows

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