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Bile duct serving liver segment VII

The bile duct of liver segment VII (Couinaud segment VII) is a segmental intrahepatic bile duct belonging to the right posterior sectoral system. It drains bile from hepatocytes in the superior-posterior portion of the right lobe of the liver. This duct converges with the segment VI duct to form the right posterior sectoral duct, which subsequently joins the right anterior sectoral duct to form the right hepatic duct.

Because of its deep and posterior location, the segment VII duct is clinically relevant in liver surgery, transplantation, and interventional radiology.

Synonyms

  • Segment VII bile duct

  • Right posterior superior bile duct

  • Posterior sectoral bile duct (segment VII component)

Origin, Course, and Termination

  • Origin: Arises from bile canaliculi of hepatocytes in segment VII (superior-posterior right lobe)

  • Course: Intrahepatic course through portal triads of segment VII, running alongside the segmental branch of the portal vein and hepatic artery (Glisson’s triad)

  • Termination: Joins the segment VI bile duct → forms right posterior sectoral duct → drains into right hepatic duct

Relations

  • Runs with segmental portal vein branch (posterior superior branch) and segmental hepatic artery branch within Glisson’s sheath

  • Lies deep within the parenchyma of the posterior right lobe

  • Closely related to hepatic veins superiorly and diaphragm posteriorly

Function

  • Drains bile from segment VII hepatocytes into the right posterior sectoral duct

  • Maintains normal bile excretion and flow toward the common hepatic duct

  • Serves as an important surgical and radiologic landmark in segmental liver resection

Clinical Significance

  • Anatomic variation: Bile ducts of segment VII may drain directly into right hepatic duct or, rarely, into common hepatic duct or left hepatic duct → important in surgery and transplantation

  • Obstruction: Segmental cholestasis may occur due to localized stones, tumors, or strictures

  • Tumor involvement: Cholangiocarcinoma or hepatocellular carcinoma may invade or obstruct segmental ducts

  • Interventional procedures: Percutaneous transhepatic biliary drainage (PTBD) often accesses segment VII or VIII ducts due to posterior location

MRI Appearance

T1-weighted images:

  • Duct lumen: dark (low signal)

  • Surrounding liver parenchyma: intermediate signal

  • Fat: bright, aiding duct identification

T2-weighted images:

  • Duct lumen: bright (high signal)

  • Narrow ducts may not be seen unless dilated

STIR (Short Tau Inversion Recovery):

  • Duct fluid: bright hyperintensity

  • Surrounding fat suppressed → improves duct conspicuity

T1 Fat-Sat Post-Contrast:

  • Duct wall may enhance slightly if inflamed

  • Pathology (tumor, stricture): enhancing mural thickening or intraluminal lesion

T2 Fat-Saturated HASTE:

  • Duct lumen: very bright signal

  • Provides rapid depiction of bile ducts, especially in MRCP screening

  • Stones: dark filling defects within bright lumen

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

  • Depicts duct as a high-signal tubular structure within liver

  • Allows 3D biliary tree reconstruction and assessment of sectoral drainage patterns

Thick-slab T2 Fat-Saturated HASTE:

  • Segmental duct appears as part of bright tubular system on projectional MRCP image

  • Useful for quick overview of ductal anatomy and obstruction

CT Appearance

Non-Contrast CT:

  • Normal intrahepatic ducts usually not visible unless dilated

  • If dilated: low-attenuation tubular structure in posterior right lobe

  • Stones: may appear as hyperdense filling defects (if calcified)

Post-Contrast CT:

  • Duct wall may enhance slightly if inflamed

  • Dilated ducts appear as non-enhancing, low-attenuation tubular channels

  • Tumor infiltration: enhancing soft tissue masses narrowing or obliterating duct lumen

MRI image

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