Ischemic Bile Duct Injury

Solitary or multifocal strictures of variable length

• Cholangiography: Gold standard for diagnosis

Appearance may be identical to PSC with “beading” of biliary tree (alternating stenosis, normal ducts, and mild dilatation)

Biliary casts appear as filling defects within duct lumen

• CT: Scattered irregular biliary dilatation with bile duct wall thickening and hyperenhancement

Presence of intrahepatic biloma or liver infarct should prompt careful assessment for HAT/HAS

Bile duct casts appear as intraductal hyperdense material

CT not sensitive for early stage ischemic injury

• MR: Linear high T1 signal intensity may be visualized within dilated central ducts, characteristic of biliary cast

PATHOLOGY

• Classically due to hepatic artery thrombosis, but possible without arterial compromise (ischemic-type biliary lesions)

• Also associated with prolonged warm and cold ischemic time, ABO incompatibility, and chronic rejection

CLINICAL ISSUES

• Initial treatment: Endoscopic or percutaneous dilatation/stenting of strictures and clearing of biliary casts

• Roux-en-Y hepaticojejunostomy for extrahepatic strictures unresponsive to dilatation/stenting

• Retransplantation may be necessary in patients with secondary biliary cirrhosis, recurrent cholangitis, or progressive cholestasis

(Left) Coronal CECT MIP reconstruction in a liver transplant patient demonstrates abrupt occlusion of the hepatic artery near its origin from the celiac artery.

(Right) Cholangiogram in the same patient demonstrates features of ischemic cholangiopathy due to hepatic artery occlusion, including a dominant stricture in the common duct and irregularity of the intrahepatic ducts.

(Left) ERCP of a patient with jaundice after liver transplant shows a filling defect in the hilum, representing a hilar biliary cast , and diffusely irregular intrahepatic ducts. The patient’s course was complicated by portal vein thrombosis and rejection, but the hepatic artery was patent on US.

(Right) T1WI FS MR of the same patient shows a typically high signal cast at the duct bifurcation. Multiple ischemic and immunological insults may result in the strictures and casts that are characteristic of ischemic cholangiopathy.

TERMINOLOGY

Synonyms

• Ischemic cholangitis, ischemic cholangiopathy

Definitions

• Nonanastomotic biliary strictures in liver allograft originally described in setting of hepatic artery thrombosis (HAT) or stenosis (HAS), but now known to occur due to a wide variety of other microangiopathic and immunological injuries

IMAGING

General Features

• Best diagnostic clue

Nonanastomotic biliary strictures in liver allograft

• Location

Can involve intrahepatic &/or extrahepatic ducts

Predominant involvement of middle 1/3 of common bile duct and hepatic duct confluence > intrahepatic ducts

2 common patterns

– Strictures beginning at hilum and extending peripherally

– Multiple scattered intrahepatic strictures

• Morphology

Can be solitary or multifocal strictures

Variable length: Short or long segment

Radiographic Findings

• Cholangiography (ERCP or PTC) is gold standard for diagnosis of ischemic cholangitis

Cholangiographic appearance may be nearly identical to primary sclerosing cholangitis

Luminal irregularity of bile ducts with beaded appearance (alternating sites of stenosis, normal ducts, and mild dilatation)

– Strictures evolve over time, beginning as sites of irregularity and developing into fibrotic strictures

– Ductal narrowing with upstream dilatation

– Rare diffuse duct necrosis and biliary sloughing

Biliary casts appear as filling defects within duct lumen

May demonstrate communication of bile ducts with intrahepatic bilomas

CT Findings

• Scattered irregular biliary dilatation with bile duct wall thickening and hyperenhancement

Presence of intrahepatic biloma or liver infarct in post-transplant setting should prompt careful assessment of hepatic artery for HAT/HAS

– Doppler US to screen, then CTA confirmation if Doppler positive

Bile duct casts, highly suggestive of ischemic cholangiopathy, appear as linear hyperdense material within bile duct

– May not be readily distinguishable from stone on CT (both may appear hyperdense)

Biliary necrosis, debris, and bilomas with advanced ischemia (particularly in setting of HAS/HAT)

• CT not sensitive for early stage ischemic-type biliary lesions (ITBL)

Transplanted liver may not develop biliary dilatation despite severe ductal stenosis

If high clinical suspicion for ITBL, proceed to cholangiography (ERCP, PTC, or MRCP)

• CTA can show hepatic artery narrowing or thrombosis

MR Findings

• Strong correlation between MRCP and cholangiography

High sensitivity, specificity, and predictive values for evaluation of ischemic-type biliary injury

• Hepatobiliary contrast agents (i.e., Eovist) can be used for cholangiographic images in hepatobiliary phase

Most often utilized to evaluate for strictures at hepaticojejunostomy

• T2WI, MRCP, and T1WI C+ Eovist cholangiographic images demonstrate luminal irregularity, stenosis, and scattered biliary ductal dilatation

• May be associated with T2-hyperintense intrahepatic bilomas or liver infarcts

• Linear high T1 signal intensity may be visualized within dilated central ducts, characteristic of biliary cast

Extremely uncommon in absence of ischemic cholangiopathy and virtually diagnostic

MR allows distinction between cast (T1 hyperintense) and stones (hypointense on all pulse sequences)

• Advantage of noninvasively evaluating other biliary complications (anastomotic stricture, stones, leak, etc.)

• MRA can show hepatic artery thrombosis or stenosis

Ultrasonographic Findings

• Grayscale ultrasound

Poor sensitivity for early stage ischemic-type biliary injury

May show intrahepatic ductal dilatation and thickening

Biliary casts appear as echogenic material within dilated bile ducts

Advanced biliary ischemia due to HAT or HAS may result in presence of intrahepatic fluid collections (bilomas)

Extrahepatic biliary dilatation is nonspecific finding in post-transplant liver and does not necessarily imply ischemic cholangiopathy

– Nonobstructive dilatation of extrahepatic ducts (without intrahepatic biliary dilatation) may be due to papillary dyskinesia or discrepancy between size of donor and recipient ducts

• Pulsed Doppler