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Bile duct serving liver segment VI

The bile duct of liver segment VI is a small intrahepatic duct responsible for draining bile from segment VI of Couinaud’s classification, located in the posterior inferior part of the right hepatic lobe. It merges with the bile duct of segment VII to form the right posterior sectoral duct, which then joins the right anterior sectoral duct to form the right hepatic duct.

This duct is crucial in segmental liver surgery, transplantation, and interventional radiology, as accurate mapping of intrahepatic bile ducts prevents complications such as bile leaks and strictures.

Synonyms

  • Segment VI bile duct

  • Posterior inferior right hepatic segmental duct

  • Intrahepatic bile duct of Couinaud’s segment VI

Origin, Course, and Termination

  • Origin: Collects bile from intrahepatic canaliculi of liver parenchyma in segment VI (posterior inferior right lobe)

  • Course: Runs within the portal triad (Glisson’s sheath) alongside the segment VI branch of the portal vein and hepatic artery

  • Termination: Joins the segment VII bile duct → forms right posterior sectoral duct

Relations

  • Anteriorly: Posterior aspect of segment V liver parenchyma

  • Posteriorly: Posterior abdominal wall and diaphragm

  • Medially: Segment VII bile duct (superiorly) and right posterior portal structures

  • Laterally: Liver capsule at posterior right lobe

Function

  • Collects and drains bile produced by hepatocytes of segment VI

  • Contributes to the right posterior sectoral duct → right hepatic duct → common hepatic duct → bile delivery to duodenum

  • Maintains bile flow required for digestion and fat absorption

Clinical Significance

  • Segmental surgery (hepatectomy): Precise identification essential to avoid bile leak

  • Liver transplantation: Accurate mapping critical in donor and recipient biliary reconstruction

  • Strictures/obstruction: May occur from stones, tumors, or iatrogenic injury

  • Interventional radiology: Target for percutaneous biliary drainage (PTBD) in localized obstruction

  • Biliary anatomy variants: Segment VI duct may have variable confluence patterns with neighboring ducts

MRI Appearance

T1-weighted images:

  • Duct lumen: dark (low signal intensity)

  • Surrounded by liver parenchyma (intermediate signal)

T2-weighted images:

  • Duct lumen: bright (high signal) due to bile

  • Wall: thin, dark hypointense lining

STIR (Short Tau Inversion Recovery):

  • Fluid-filled duct: bright hyperintense signal

  • Fat suppressed, improving visualization against liver tissue

T1 Fat-Sat Post-Contrast:

  • Duct wall may show subtle enhancement

  • Pathology: strictures or cholangitis cause wall thickening and enhancement

  • Stones: non-enhancing intraluminal defects

T2 Fat-Saturated HASTE (single-shot):

  • Segment VI duct appears as a bright linear/tubular structure within liver parenchyma

  • Stones or air: appear as dark signal voids

  • Excellent rapid depiction for obstruction screening

T2 TSE Fat-Saturated 3D (MRCP sequence):

  • Provides high-resolution 3D reconstruction of intrahepatic ducts

  • Segment VI duct clearly seen joining segment VII duct → right posterior sectoral duct

  • Useful for mapping variants and planning interventions

Thick-slab T2 Fat-Saturated HASTE:

  • Displays duct as a bright tubular projectional image within the biliary tree

  • Ideal for overview MRCP to evaluate biliary drainage pattern

CT Appearance

Non-Contrast CT:

  • Duct usually not visualized unless dilated

  • When dilated: appears as a low-attenuation tubular structure within right posterior liver

  • Stones: hyperdense if calcified

Post-Contrast CT:

  • Duct wall may enhance faintly

  • Dilated duct: clearly visible as low-density channel within enhancing parenchyma

  • Strictures, cholangitis, or tumors: wall thickening or irregular enhancement

  • Abscess or secondary infection: rim-enhancing collections around biliary tree

MRI image

Bile duct serving liver segment VI MRI axial anatomy image-img-00000-00000