Pre-operative imaging evaluation in liver transplantation

1. Imaging of Preoperative
Liver Transplantation
Capt. Soe Moe Htoo
Radiology Dept., DSLH

2. Introduction
• Liver transplantation is considered the only curative treatment for patients with
end stage liver disease
• Successful treatment for unresectable small hepatocellular carcinoma (HCC)
• Outcome had greatly improved during the last years giving the advance of
immunosuppressive treatments and surgical techniques
• Successful liver transplantation requires a multidisciplinary approach with careful
preprocedural preparation as well as long term follow up.
• Radiologists play a crucial role in the pre-procedural workup and the short/long
term follow up.
• Understanding the surgical procedure and its potential complications are
essential for an adequate radiological assessment

3. Indications for Liver Transplantation
Condition Indications
Alcoholic cirrhosis Patients must abstain from alcohol for 6 months, undergo treatment for
alcohol abuse, and have a strong psychosocial support system
Chronic hepatitis Hepatitis B, C, and D infection; autoimmune hepatitis; chronic drug use;
cryptogenic cirrhosis; chronic active hepatitis
Primary hepatic tumors Hepatocellular carcinoma (grade 1 or 2, <5 cm, and no extrahepatic
metastases or macrovascular invasion)
Cholestatic diseases Primary biliary cirrhosis, sclerosing cholangitis, cystic fibrosis, biliary atre-
sia, Caroli disease, Alagille syndrome, Byler disease, familial cholestatic
syndromes
Fulminant liver failure Drug toxicity, toxins, viral hepatitis infection
Metabolic disease a-1-antitrypsin deficiency, glycogen storage disease, Wilson disease, hemo-
chromatosis
Other conditions Budd-Chiari syndrome, parenteral nutrition–induced cirrhosis, trauma

4. Contraindications for Liver Transplantation
Absolute contraindications
• Active extrahepatic malignancy
• Diffuse hepatic tumor invasion
• Thrombosis of the entire portal and
superior mesenteric venous system
• Active or uncontrolled systemic
infection
• Active substance or alcohol abuse
• Severe cardiopulmonary disease
• Lack of social support
• Noncompliance
• Fatty infiltration >30%
Relative contraindications
• Age
• Cholangiocarcinoma
• Portal vein thrombosis
• Chronic or refractory infection
• HIV infection
• Previous malignancy
• Active psychiatric disorder
• Poor social support

5. Patient Selection
• Unfortunately, the disparity between the number of recipients and available
livers has been increasing.
• Thus, under the current guidelines, the sickest patients are given priority for
transplantation.
• Priority is given to
• patients with end-stage liver disease and who have the greatest risk for death
within 3 months due to progressive deterioration
• acute decompensation from chronic liver disease
• development of fulminant liver failure in those who were previously healthy

6. Model for End-Stage Liver Disease (MELD score)
• Used to assess the severity of chronic liver disease.
• Determined which patients need to do urgent liver transplantation.
• MELD scores range from 6 to 40
• 6 indicating the least sick patients
• 40 indicating the sickest patients.
• MELD scores are calculated on the basis of
• total bilirubin,
• international normalized ratio (INR)
• creatinine
• MELD scores Equation:
3.8 × log (e) (amount of bilirubin) + 11.2 × log (e) (INR) + 9.6 log (e) (amount of creatinine)

7. • According to the studies,
• 3-month mortality rate with a MELD score of 40 is 100%.
• For score 30–39 is 83%
• For score 20–29 is 76%
• For score 0–19 is 27% and
• For score 10 is 4%.

8. Hepatocellular Carcinoma
• Among patients with HCC, priority for liver transplantation should be given
to those with stage T2 disease
• Patients with T1 disease have high survival rates without transplantation
• T3 disease have a high rate of recurrence.

9. • T1 - A single tumor (of any size) without blood vessel invasion
• T2 - A single tumor >2 cm with vascular invasion or multiple tumors (none >5 cm)
• T3a - multiple tumors, with at least one is larger than 5 cm.
• T3b - extend into a major branch of the portal or hepatic vein.
• T4 - tumors extend beyond the liver, except gallbladder
HCC (T-staging)

10. • MELD scores are not a reliable indicator of mortality among patients who die
from HCC.
Milan criteria
• Eligible for liver transplantation in HCC patients;
• A single tumor that is smaller than 5 cm
• Up to three tumors that are 3 cm or smaller
• No vascular invasion
• No extrahepatic disease
University of California San Francisco (UCSF) criteria
• Eligible for transplantation in;
• single tumor that is 6.5 cm or smaller
• three or fewer tumor nodules are present, with the largest being 4.5 cm or
small

11. Tumor Volume
• When a cutoff of 115 𝒄𝒎𝟑 is used for selecting transplantation, post-
transplantation outcomes are no different from those achieved with the Milan
and UCSF classification systems.
High Recurrent Potential
• Tumor larger than 6 cm
• Disease that progresses after pre-transplantation treatment
• Tumor that is exposed to the liver surface.

12. Types of Liver Transplantation
Currently, there are three main types of liver transplantation:
1. Cadaveric
2. Liver Donor Liver Transplantation (LDLT) , and
3. Split-liver grafting.
Cadaveric
• Most common type
• Whole liver transplantation
• Technically successful
• Limited organ available
LDLT
• 10% of adult liver transplant
• Minimal ischemic time
• Planned surgical time
• Higher risk for complications
for both the donor and
recipient
• Smaller graft size
Split Liver
• Cadaveric liver is anatomically
divided and transplanted into
multiple recipients
• An extended right-liver split
• Technical difficulties to
sharing blood vessels and
obtaining good biliary
drainage

13. Living Donor Liver Transplantation
• The advantages of LDLT include a lack of preservation injuries and an ability to
perform the procedure on an elective basis.
• The disadvantages include a risk for complications in the donor.
• Hepatic segments cannot be transplanted separately because the transplanted
liver tissue requires arterial supply, venous drainage, and biliary outflow.
• The decision of whether to perform hepatectomy is determined on:
• Donor safety
• Size of the recipient
• Left lateral hepatectomy grafts are ideal for smaller recipients.
• Left or right hepatectomy grafts are more useful for larger patients.

14. Segmental Anatomy of Liver

15. Left Lateral Hepatectomy
• Most common LDLT technique
• Includes segments II and III of the resected liver
• Represents 20-25% of the whole liver volume

16. Left Lobectomy
• Includes segments 2, 3, and 4 together (known as the left lobe)
• Represents approximately 40% of the whole liver volume
• Harvesting the middle hepatic vein to obtain a reasonably large graft and
maintain high tissue viability for transplantation.

17. Right Hemihepatectomy
• Includes segments V, VI, VII and VIII (entire donor right lobe), Rt. hepatic artery,
Rt. hepatic vein, Rt. bile duct and Rt. portal vein
• Account for approximately 60% of the total liver volume
• Performed if the volume of the donor’s left lobe is more than 30% of the total
hepatic volume.
• Inclusion of the middle hepatic vein in the graft is controversial; however, it may
be included to avoid congestion of the right paramedian segment in the recipient.

18. • The caudate lobe usually remains in the donor because it is directly perfused by
the right or left portal vein branches.
• Middle hepatic vein remains with the donor when the right side of the liver is
being donated (Controversial)
• MHV is harvested when left hepatectomy is performed.
• The recipient left and middle hepatic veins are joined, followed by end-to-end
anastamosis with the donor hepatic vein.
• Thus, the venous ouflow is optimized by reconnecting the major veins and
anastomosing with a single reconstructed recipient vein.

21. Split-Liver Grafting Technique
• Two types of split-liver grafting
• Left lateral split
• Extended right split
• The classic left lateral split is performed at the falciform ligament
• Right extended graft (segments I and IV to VIII) used in adults
• Left lateral graft (segments II and III) used in children who are no larger than
30 kg.
• The extended right split, which results in right (segments V–VIII) and left
(segments II–IV) hemilivers, is performed in two adult recipients.
• Typically,
• common bile duct and inferior vena cava (IVC) are part of the right liver graft
• main arterial trunk and middle hepatic vein are part of the left liver graft.

22. Pre-operative Imaging
• Correct identification of donor anatomy is essential to determine whether the
donor is a suitable candidate and hepatectomy may be safely performed with no
risk to the donor.
• Preoperative evaluation of liver parenchyma, vascularization and biliary system in
both donors and recipients by using;
1. Magnetic resonance imaging (MRI),
2. Computed tomography (CT) or
3. Ultrasound (US) imaging with Doppler evaluation

23. CT Cholangiogram
• CT cholangiography is performed after intravenous infusion of cholangiographic
agent.
• To reduce the risk for allergic reactions:
• 20 mL of 52% iodipamide meglumine (cholangiographic contrast) is diluted in
80 mL of normal saline
• infused over a period of 30–60 minutes.
• Fifteen minutes after completion of the infusion, spiral CT of the liver is
performed.

24. • In some institution, contrast-enhanced MR imaging and MR
Cholangiopancreatography (MRCP) are the first choice for preoperative
evaluation,
1. radiation free,
2. ensure accurate parenchymal analysis
3. adequate evaluation of vasculature and biliary system

25. Living Donor
 Cross sectional liver imaging of the donor is mandatory before liver donation to
detect any contraindication or finding that may modify the surgical approach.
 Liver parenchymal evaluation, diffuse (mainly steatosis) or focal
(benign/malignant) conditions
 Identification of anatomical variants

26. Liver Volume Calculation
• Very important to calculate graft and remnant liver volumes before hepatic
resection, in order to ensure adequate hepatic function and liver regeneration
after surgery, both in recipients and donors.
• A minimal residual volume of 30% is required to prevent small-for-size syndrome
on the assumption that the liver parenchyma is disease free (i.e. steatosis)
• Ideally, the recipient should receive a graft similar in size to the native organ.
• But a minimum corrected graft-to-recipient body weight ratio (GRBW) of 0.8% is
still acceptable.

27. Liver Parenchymal Evaluation
 Look for presence of incidental hepatic focal lesions.
 Majority are benign, presence of any large lesion or a malignant lesion is a
contraindication for organ donation.
 Any diffuse liver disease, such as fatty infiltration should be identified.
 Hepatic steatosis carries a high risk of postoperative liver dysfunction in donors
and graft non-function in recipients.
 Each 1% increase in hepatic fat content, functional mass of donor liver reduces
by 1%.
 In the donor liver, moderate to severe steatosis (≥30% fat) is considered
unacceptably high and should be rejected for donation.

28. Severe hepatic steatosis. Axial NECT
image shows a decreased hepatic
attenuation in comparison with spleen.

29. Vascular Anatomy
 Anatomical variants of the hepatic vasculature are relatively frequent.
 Adequate arterial inflow to graft liver is necessary for avoidance of biliary
necrosis.
 Patency of the portal vein is crucial for graft survival and liver regeneration.
 Patent hepatic vein outflow is needed to prevent hepatic congestion and graft
dysfunction.
 MDCT is an excellent tool in providing a detailed road map of normal and variant
hepatic vascular anatomy in the donor, and helps in guiding the surgical
approach.
 Any variant should be clearly described and reported for an appropriate pre-
procedural planification.
 Some anatomical variants are contraindication to liver donation.

30. Hepatic arterial anatomy and variants
 MDCT allows accurate delineation of the intrahepatic tertiary arterial branches
as small as 1 mm in size.
 In normal hepatic arterial anatomy, common hepatic artery (CHA) arises from
the celiac axis.
 It divides into gastro-duodenal artery (GDA) and proper hepatic artery.
 Proper hepatic artery ascends toward the liver hilum and divides into left
hepatic artery (LHA) and right hepatic artery (RHA).
 LHA supplies the entire left hemi-liver, including segment IV.
 The RHA divides into anterior and posterior sectional branches which supply the
anterior (VIII and V) and posterior sections (VI and VII) of right hemi-liver,
respectively.

31. Coeliac Axis

32.  In right posterior sectional grafts, a separate single artery to the posterior
segments of right lobe (segments VI and VII) should be identified on imaging for
safe anastomosis.
 Identification of the dominant arterial supply to segment IV is very important
because its integrity is absolutely necessary for the regeneration of remnant
donor liver.
 Segment IV artery usually arises from the LHA
 However (approximately in 11% of patients), it arises from the RHA
 May traverse the transection plane to ascend into the left lobe
 In such cases, RHA is divided distal to the origin of segment IV artery.
 It is important to ensure preoperatively that the RHA segment distal to
segment IV artery is of sufficient length to permit anastomosis.

33.  Presence of accessory arteries to a lobe requires two arterial anastomoses, and
therefore increases the surgical time and poses a higher risk of postoperative
hepatic arterial thrombosis.
 Presence of multiple small vessels in a lobe precludes donation.
 Other surgically important arterial variants include direct origin of hepatic artery
from the aorta or entire hepatic artery from the SMA, and separate origin of all
hepatic arterial branches from CHA.

34. Segment IV artery origin from RHA Intraoperative photograph of segment IV
artery (Black arrow) arising from
RHA(open arrow)

35. Portal vein anatomy and variants
 Classically, the main portal vein trunk branches into right and left portal veins at
porta hepatis.
 The right portal vein (RPV) subsequently divides into anterior and posterior
sectional branches at a variable length from the RPV origin.
 The right anterior portal vein (RAPV) supplies segments VIII and V, while the
right posterior portal vein (RPPV) supplies segments VI and VII of the liver.
 The left portal vein (LPV), on the other hand, ascends along the falciform
ligament and supplies the entire left hemi-liver (segments II, III, and IV)
 This normal portal vein anatomy is most suitable for donation, as only one
anastomosis is required between the donor and recipient portal veins.

36.  Nakamura and associates described a classification of portal vein branching
patterns with five variations (A-E),
o Type A is the usual bifurcation type (normal branching pattern).
o Type B is a trifurcation pattern without the trunk of RPV.
o Type C, RAPV arises separately from the proximal or extra-parenchymal part
of LPV.
o Type D, RAPV arises separately from a distal or intra-parenchymal portion of
LPV.
o Type E, branches of segment V and VIII originate separately from LPV.
 Trifurcation of the portal system will require double anastomosis if right lobe
donation is performed and should be noticed.
 When the right anteromedial branch arises from the left portal vein, the
resection of the latter can have deleterious effects on segments IV, V and VIII.

37.  Intraparenchymal branching of RAPV from LPV (type D) and type E branching
patterns are uncommon and are considered absolute contraindications for
surgery.

38. Hepatic venous anatomy and variants
 Three major hepatic veins which drain liver parenchyma into the inferior vena
cava.
 Right hepatic vein (RHV) is the largest and drains a major part of right hemi-liver
into IVC.
 Middle hepatic vein (MHV) drains central liver segments (i.e. IV, V, and VIII),
 Left hepatic vein (LHV) predominantly drains from segments II and III
 In 60-70% of cases, MHV and LHV join to form a common stump before entering
IVC, while RHV opens directly into IVC.
 Even when MHV and LHV open separately into IVC, an intimate relationship
exists between the two in 100% of cases.

39.  Drainage pattern of the MHV should be thoroughly evaluated, since it is an
important surgical landmark.
 The usual position of the middle hepatic vein is between segments VIII and IV.
 It is important to identify any variation in MHV as hepatectomy plane in right hemi-
liver donation is about 1 cm to the right of the middle hepatic vein, along the
gallbladder fossa.
 Branches from the anterior segments of right lobe (V and VIII) draining into the MHV
run along the parenchymal resection plane.
 These veins need to be preserved and re-anastomosed in the recipient to prevent
congestion and risk of graft failure in the transplanted right hemi-liver.

40.  It is also important to determine if an accessory inferior right hepatic vein is
present.
 They are seen in 40-50% of patients.
 Majority of these veins drain segments VI and VII
 Inferior RHVs more than 4 mm in diameter should be preserved and
anastomosed separately to recipient’s IVC to prevent hepatic congestion.
 Accessory hepatic veins with a caliber of 5 mm or more require separate
anastomosis to the IVC.

41. 3D image showing drainage of right
anterior sector veins (arrows) into MHV

42. Biliary Anatomy
 In routine clinical practice, preoperative assessment of biliary tree in potential
liver donors is done using MR cholangiography.
 The common hepatic duct (CHD) emerges from the convergence of right and left
bile ducts.
 Variant biliary anatomy has been observed in 30-35% patients.
 With increasing surgical expertise, a bile duct variation rarely excludes a person
from being a liver donor.
 However, it very important to preoperatively evaluate unusual patterns of bile
duct branching, in order to modify the cutting plane during graft retrieval and
the pattern of ductal anastomosis in the recipient.
 This helps in reducing postoperative biliary complications.

43. Recipient
• Evaluation and description of the liver anatomy
• Size, number, and characteristics of the visualized lesions.
• Tumors should be localized according to the Couinaud classification system to
facilitate their identification during resection, intervention, and other treatment
procedures.
• Imaging of the recipient liver should be performed as close to the time of
transplantation as possible because tumors may grow rapidly, invade local
structures, or metastasize, which may affect the stage of disease, management
perspective, and surgical technique.

44.  It is also critical to report the proximity of the tumor to important structures
such as major blood vessels, the gallbladder, and central bile ducts because the
outcome may be affected.
 Identification of vascular invasion is important because it is a contraindication
for transplantation.
 Varices develop as a result of sustained severe portal hypertension.
 The peri-caval and peri-hepatic varices should be reported due to their
association with increased intraoperative bleeding.
 To exclude extrahepatic malignancy, CT of the chest and abdomen should be
performed.

45. Conclusions
• Preoperative imaging in potential liver transplantation patients includes proper
evaluation of the liver parenchyma and vascular and biliary anatomy.
• Understanding the indications, contraindications, surgical techniques and
potential complications are important for a thorough assessment.
• A multidisciplinary approach is essential in liver transplantation in order to
achieve the best outcome, with the radiologist playing a crucial role during the
whole process.

46. THANK YOU
HAVE A NICE DAY!