Hepatic Transplantation

Published on 19/07/2015 by admin

Filed under Radiology

Last modified 22/04/2025

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 No reliable imaging findings to suggest or confirm diagnosis

• Biliary leak

image From entry of T tube: Easily treated
image From biliary anastomosis: Requires revision
image From intrahepatic ducts: Biliary necrosis; catastrophic
• Biliary obstruction

image Balloon dilation and stenting
• Hepatic artery stenosis

image Damped waveform in hepatic artery distal to stenosis: Slow systolic upstroke; decreased resistive index (< 0.5)
image Narrowing at hepatic artery anastomosis with turbulent flow, focally ↑ velocity (> 0.3 m/s)
image CT (or MR) angiography for detailed analysis
• Hepatic artery thrombosis

image Accompanied by biliary necrosis; catastrophic
• Hepatic arterial pseudoaneurysm

image From biopsy or surgical error
• Portal vein stenosis

image Uncommon: Treated by angioplasty and stent
• IVC anastomotic stenosis

image Can be suggested by US (anastomotic narrowing, turbulent, rapid flow across anastomosis), CT, or MR
• Recurrent disease within allograft

image Primary sclerosing cholangitis: Tends to recur
image Hepatocellular carcinoma
image Recurrent viral hepatitis or primary biliary cirrhosis
• Extrahepatic complications

image Abdominal fluid collections
image Post-transplant lymphoproliferative disorder
image
(Left) Graphic shows the typical anatomy for whole liver transplantation. Some liver is cut away to show anastomoses more clearly, as there are a number of common variations for vascular and biliary anastomoses.

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(Right) Graphic shows the typical anatomy of an adult partial-liver recipient (living donor). Note the biliary-enteric anastomosis to a Roux limb. Complications are more common than for whole liver allografts due to the many transected vessels and ducts and the small size of the structures for anastomosis.
image
(Left) Axial CECT shows a “halo” of low density surrounding some of the portal veins. This is a typical feature of periportal lymphedema, which is common and of no clinical concern in the early post-transplantation setting.

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(Right) T-tube cholangiogram shows a mild waist-like narrowing at the biliary anastomosis image without dilation of the upstream bile ducts. This is the normal appearance of a duct-to-duct anastomosis.

TERMINOLOGY

Definitions

• Whole liver allograft (cadaver donor)

image Orthotopic liver transplantation (OLT)
image Included from donor

– Intact inferior vena cava (IVC)

image Anastomosed end-to-end or as “piggy-back” side-to-side
– Hepatic artery (HA)

image Anastomosed end-to-end, sometimes with aortic (Carrel) patch
– Portal vein (PV)

image End-to-end anastomosis
– Bile duct

image Anastomosed end-to-end with recipient duct (70%) or to Roux limb
• Cadaver split liver (2 halves to separate recipients)

image Right lobe to adult recipient (IVC, HA, PV, bile duct)
image Left lobe to child recipient (complex anastomoses)
• Living donor transplant

image Child recipient: Generally receives lateral segment of donor liver
image Adult recipient: Receives right lobe of donor
image Complex biliary and vascular anastomoses

IMAGING

Normal Post-Transplantation Findings

• Right pleural effusion (usually resolves spontaneously)
• Right adrenal hematoma

image Adrenal veins injured or ligated during OLT
image No clinical importance
• Periportal lymphedema

image Lucent “halo” around PVs and IVC
image No significance; resolves spontaneously
• Vascular and biliary anastomoses may show waist-like narrowing

image Should not have functional narrowing
image Normal indices on US: Hepatic artery

– Resistive index (RI): 0.5-0.7
– Rapid systolic acceleration time (< 80 ms)
– Flow velocity at anastomosis < 200-300 cm/s
image Portal vein

– Mild phasicity with respiration; no turbulent flow
image Hepatic veins (HV), IVC

– Triphasic waveforms reflective of cardiac contractility
• Biliary anastomosis

image Waist-like narrowing without dilation of upstream ducts
image Duct-duct anastomosis may be stented with T tube for several months

– Allows access for cholangiography

image Performed in early post-OLT and repeated as indicated
• Liver parenchyma

image Normal texture by all imaging modalities
image Partial liver recipients

– Liver grows to near normal volume within  months

Pre-Transplantation Evaluation

• Imaging and clinical evaluation of severity of cirrhosis and portal hypertension

image Size and morphology of liver
image Ascites, splenomegaly, extent of varices
image Presence and stage of hepatocellular carcinoma (HCC)

– Size, number, presence of vascular invasion, extrahepatic spread
– Early stage HCC may be good candidate for transplantation (receives increased MELD points)
image Model for end-stage liver disease (MELD)

– Based on etiology of cirrhosis, plus serum creatinine, bilirubin, and International Normalised Ratio (INR)
• Detailed evaluation of hepatic vessels

image Note any anomalies (e.g., “replaced” HA)

– Check for severe atherosclerosis, median arcuate ligament compression of celiac axis
image PV: Check for thrombosis, mural calcification, diminutive size
image HVs: Check for thrombosis (Budd-Chiari)

Allograft Rejection

• No reliable imaging findings to suggest or confirm diagnosis
• Clinical suspicion leads to US-guided biopsy of allograft

image US is best modality for guidance

– Safest, least expensive, least discomfort

Biliary Complications

• Biliary leak

image Leak from entry of T tube

– Often encountered after removal of T tube after several months
– Recognized by cholangiography, biliary scintigraphy, or aspiration of fluid collection identified by US or CT
– Easily confirmed by ERCP and treated by placement of temporary biliary stent
image Leak from biliary anastomosis

– Usually due to surgical error
– Often requires surgical revision of anastomosis
image Leak from intrahepatic ducts

– May be due to biopsy (resolves spontaneously)
– Usually due to biliary necrosis

image Result of HA stenosis or thrombosis
– Usually requires retransplantation in adults
image Strictures or irregularity of intrahepatic ducts

– Nonspecific
– Possible etiologies include incomplete distention (artifact), infection, rejection, ischemia, recurrent primary sclerosing cholangitis
• Biliary filling defects

image Stones: Usually late complication
image Debris: Cholangitis, infection, rejection, ischemia
image May respond to endoscopic sweeping of debris from duct ± temporary stent
• Biliary obstruction

image Anastomotic

– Complete: Requires surgical intervention
image Partial

– Usually responds to balloon dilation and stenting

Vascular Complications

• HA stenosis

image Clinical signs: Worsening liver function
image US: Usually 1st imaging study to suggest diagnosis

– Examine artery in porta hepatis and within liver (main, right, and left HA)
– Damped (tardus parvus) waveform in HA distal to stenosis

image Slow systolic upstroke; decreased RI (< 0.5)
– Narrowing at HA anastomosis with turbulent flow, focally ↑ velocity (> 0.3 m/s)
image CT (or MR) angiography can confirm stenosis, occlusion, redundancy, kinking, or other abnormalities of HA
image Catheter angiography usually reserved for intervention (balloon angioplasty ± stent)
• HA thrombosis

image Usually marked by liver dysfunction, fever, malaise
image Imaging shows no flow within HA beyond anastomosis
image Often accompanied by biliary necrosis (bile ducts totally dependent on arterial supply)

– Focal hypodense lesion or fluid collection within liver

image May have branching pattern along porta triads
– Can be confirmed by needle aspiration and percutaneous drainage of biloma
– Adults: Usually fatal or requires retransplantation
– Children: May develop sufficient collateral HA flow to preserve allograft function
• Hepatic arterial pseudoaneurysm

image Intrahepatic: Usually due to liver biopsy

– May resolve spontaneously or require embolic therapy
image At HA anastomosis

– May be due to technical error or infection
– May respond to stent across aneurysm site or require surgical revision
• PV stenosis

image Relatively uncommon
image Can be suggested by US (turbulent, rapid flow across anastomosis; loss of respiratory phasicity), CT, or MR
image Confirmed by transhepatic portography

– Can be treated by angioplasty and stent
• IVC anastomotic stenosis

image Relatively uncommon
image Can be suggested by US, CT or MR (anastomotic narrowing, turbulent, flow across anastomosis)

– US: Loss of respiratory and cardiac phasicity (should be triphasic)
– May see echogenic clot within IVC caudal to anastomosis
image Presence of intraluminal pressure gradient across anastomosis confirms physiologically significant stenosis

– Can be treated by angioplasty and stent

Recurrent Disease Within Allograft

• Primary sclerosing cholangitis

image Tends to recur several years after OLT
• HCC

image Relatively uncommon with proper selection of OLT candidates with early-stage HCC (according to Milan or UCSF criteria)
image Appearance is similar to HCC in native liver

– Heterogeneous hypervascular mass with washout; tendency toward venous invasion
• Recurrent viral hepatitis or primary biliary cirrhosis

image Detected by imaging with return of cirrhotic morphology

– Widened fissures, ascites, varices
image Hepatitis B rarely recurs after transplantation due to effective antiviral prophylaxis
image Hepatitis C recurs more frequently, as prophylaxis is less effective

Extrahepatic Complications

• Abdominal fluid collections

image Loculated ascites ± infection; abscess; biloma
image Easily identified by CT
image Usually amenable to image-guided aspiration and drainage
• Post-transplant lymphoproliferative disorder (PTLD)

image Caused by Epstein-Barr viral infection and immunosuppression
image Clinical spectrum

– Polyclonal proliferation of lymphocytes

image Treated with antiviral medication
– High-grade monoclonal lymphoma (non-Hodgkin)
image Soft tissue density masses in lymph nodes, bowel, hepatic allograft, other organs and structures throughout body

– Recurrence within hepatic allograft

image Soft tissue density mass(es) with tendency toward periportal distribution

CLINICAL ISSUES

Natural History & Prognosis

• Prognosis is good for properly selected patients
• Depends largely on patient’s overall health at OLT

image Varies somewhat by etiology of liver disease

– e.g., better for patients with alcoholic cirrhosis than patients with chronic viral hepatitis
image 1 year patient survival = 80-90%; 5 year = 75-88%

DIAGNOSTIC CHECKLIST

Image Interpretation Pearls

• US is a good surveillance tool for most causes of allograft dysfunction

image Interrogate all arteries and veins separately
image
(Left) Axial CECT of a 57-year-old man with pain following recent transplantation shows a “halo” of low density image surrounding the portal veins.

image
(Right) CT section shows more of the periportal edema image while the space around the hepatic veins image is less affected. This is a common finding in the early post-transplantation setting and results from the transection of lymphatics and accumulation of lymph along the portal tracts. It generally resolves as lymphatic connections reform.
image
(Left) ERCP in a 55-year-old man shows narrowing at the biliary anastomosis image and a filling defect within the duct image, which may represent some debris. There is only mild dilation of the intrahepatic (donor) ducts.

image
(Right) The same patient was treated with an endoscopic balloon sweep, dilation of the stricture, and placement of a temporary plastic stent with good results.
image
(Left) T-tube cholangiogram in a 45-year-old woman shows a collection of extraluminal contrast medium image that originated from the site of entry of the T tube into the recipient bile duct image just distal to the anastomosis image.

image
(Right) Axial CECT in the same patient reveals an extravasated collection of bile image that was drained by US-guided placement of a pigtail catheter. The patient recovered uneventfully, with removal of the T tube several months later.
image
(Left) Color Doppler ultrasound shows a classic damped tardus parvus wave pattern of the right hepatic artery, with a slowed systolic upstroke. Also note the decreased resistive index (RI) of 0.46 image. These findings are usually indicative of hepatic artery stenosis.

image
(Right) CT angiography in the same patient demonstrates marked tortuosity of the hepatic artery and at least 1 stenotic focus at the arterial anastomosis image. Balloon angioplasty and stent were successful in relieving the stenosis.
image
(Left) Oblique pulsed Doppler ultrasound 1 day after transplant shows a normal hepatic artery Doppler waveform at the porta hepatis. RI image is 0.59, which is normal.

image
(Right) Color Doppler ultrasound in the same patient 1 day later shows a dampened flow within the hepatic artery with a tardus parvus waveform and a prolonged acceleration time (86 ms).
image
(Left) Oblique pulsed Doppler ultrasound in the same patient 2 days post transplant shows damped hepatic arterial Doppler waveforms due to hepatic arterial stenosis. Peak systolic velocity is 30 cm/s, and the RI image has fallen to 0.41.

image
(Right) CT angiography in the same case confirms a stricture at the hepatic artery anastomosis image. Hepatic arterial anastomotic stenosis or thrombosis is a common cause of allograft dysfunction and may lead to biliary necrosis and failed transplantation.
image
(Left) Axial CECT of a 61-year-old man with allograft dysfunction shows an opacified portal vein but no hepatic artery.

image
(Right) Thick plane axial reconstruction in the same case shows occlusion of the hepatic artery near its anastomosis image. This requires urgent revascularization by angioplasty or surgery, which is often unsuccessful. If this is the case, retransplantation is required.
image
(Left) Axial CECT shows a patent portal vein but no hepatic artery. There is a low-density lesion image in the liver with a branching configuration that parallels the portobiliary tracts. This is a biloma resulting from hepatic artery thrombosis.

image
(Right) A percutaneous catheter image was introduced to decompress the biloma. Injection of the catheter opacifies nondilated ducts, but many of the duct walls are necrotic and are surrounded by an amorphous collection image of bile and contrast medium.
image
(Left) CECT in a patient with deteriorating allograft function shows a large low-density lesion image that has linear, branching, and rounded components, which represent the spectrum of findings from biliary ischemia in the allograft, due to hepatic artery thrombosis. Also note the ascites image.

image
(Right) This example of hepatic artery thrombosis shows ischemic bile duct injury with an eosinophilic bile cast image. (Courtesy L. Yerian, MD.)
image
(Left) Color Doppler interrogation of the portal venous anastomosis shows turbulent rapid flow image, suggesting stenosis.

image
(Right) In the same patient, transhepatic cannulation of the portal vein and injection of contrast medium confirms a tight stenosis at the portal vein anastomosis image. This was treated with balloon dilation with good results.
image
(Left) CECT of a 60-year-old man with lower extremity edema following transplantation shows a normal-caliber suprahepatic IVC image.

image
(Right) Axial CECT in the same case at the level of the anastomosis image shows marked narrowing of the lumen. The IVC was distended on more caudal sections.
image
(Left) CT in the same case shows dilation of the IVC just caudal to the the anastomosis image of the donor and recipient IVC.

image
(Right) Inferior vena cavagram in the same patient confirms tight stenosis at the anastomosis image. At least 1 collateral vein image is opacified. Balloon dilation relieved the stricture with normalization of intraluminal pressure across the anastomosis.
image
(Left) In this patient who had hepatic dysfunction and leg swelling following a recent liver transplantation, a color Doppler sonogram suggests narrowing of the hepatic veins near their confluence image.

image
(Right) Axial CECT in the same case shows evidence of a “piggy-back” anastomosis of the donor IVC image to the recipient IVC image. The donor IVC and confluence of hepatic veins appear to be strictured image.
image
(Left) More caudal section in the same case shows a narrowed donor IVC image, a dilated recipient IVC image, and periportal edema image within the liver allograft.

image
(Right) Coronal-reformatted CT image from the same study shows distention of the recipient IVC image, stricture at the IVC anastomosis image, and periportal edema image. This patient had allograft dysfunction and leg edema.
image
(Left) CT reformation in the same case shows the strictured “piggy-back” anastomosis image to the recipient IVC image and narrowing of at least 1 of the hepatic veins image.

image
(Right) A catheter hepatic venogram confirms stenosis of the hepatic veins at the IVC anastomosis image. These strictures were balloon-dilated with improvement of symptoms and liver function.
image
(Left) Axial CECT in a 52-year-old man who had received a multivisceral transplant (liver, pancreas, and small bowel) shows the anastomotic site between the donor and recipient aorta image with this vessel feeding the small bowel, liver, and pancreatic image allografts, all of which appear normal.

image
(Right) CT section in the same patient shows a normal appearance of the infrarenal aortic anastomosis image and the pancreatic allograft image.
image
(Left) Lower CT section in the same case shows a normal appearance of the small bowel allograft image. All 3 transplanted organs functioned normally, and the patient no longer required parenteral nutrition nor insulin.

image
(Right) Coronal-reformatted CT in the same case shows the end-to-side aortic anastomosis image, which supplied blood to all 3 allografts.
image
(Left) CT in a 54-year-old woman with a multivisceral transplant shows pancreatic image and liver allografts. The small bowel allograft was normal in appearance on more caudal sections (not shown). The aortic anastomosis image is noted on this axial CT.

image
(Right) On this 3D reconstruction of the same CT scan, the donor aorta is redundant and acutely kinked image, causing luminal narrowing and requiring surgical revision. The anastomosis image with the native aorta is seen.
image
(Left) Axial CECT of a 55-year-old man with fever and weight loss months after transplantation due to post-transplant lymphoproliferative disorder (PTLD) shows hepatosplenomegaly with poorly defined hypodense masses image within both organs.

image
(Right) CT in the same patient also shows obstruction of intrahepatic bile ducts image due to a combination of the hepatic tumor image and porta hepatic adenopathy.
image
(Left) CT in the same patient shows more of the hepatic tumor (PTLD, image) and the obstructed bile ducts image.

image
(Right) CT in the same patient shows porta hepatic adenopathy image that contributed to the biliary obstruction. This was partially relieved by a biliary stent image. All of these features are typical of PTLD following hepatic transplantation.
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(Left) Axial CECT in a patient with PTLD shows dilation of the intrahepatic bile ducts and a hypovascular mass image in the hilum that compresses the portal vein and central bile ducts. Biopsy of the mass proved PTLD within the hepatic allograft.

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(Right) A more caudal section in the same patient shows the central hilar mass of PTLD image that compresses and partially obstructs the portal vein and common hepatic duct.
image
Graphic shows the typical anastomoses in a liver transplant. There are end-to-end anastomoses for the inferior vena cava, portal vein, and common bile duct. The hepatic artery is reconstructed creating a “fish-mouth” anastomosis image.

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