Topics

Topic

design image
Portal vein branch to liver segment IV

The portal vein branch to segment IV supplies the quadrate lobe (segment IV) of the liver, located between the gallbladder fossa and the falciform ligament. It typically arises from the left portal vein, dividing into superior (IVa) and inferior (IVb) branches to supply the upper and lower portions of segment IV.

Segment IV is of critical surgical importance in living donor liver transplantation, major hepatic resections, and interventional radiology. Knowledge of this portal supply is vital, as variations are frequent. In some cases, the branch to segment IV may arise from the right portal vein or directly from the main portal vein.

Failure to preserve or reconstruct this branch during surgery can result in segment IV ischemia, necrosis, or postoperative complications. In donor hepatectomy, precise identification ensures adequate perfusion of the remnant and graft liver.

Synonyms

  • Portal vein branch to quadrate lobe

  • Segment IV portal pedicle

  • Segment IVa and IVb portal branches

Function

  • Supplies nutrient-rich portal blood to segment IV of the liver

  • Ensures dual hepatic blood supply in combination with arterial branches

  • Critical for maintaining liver viability during surgery and transplantation

MRI Appearance

T1-weighted images:

  • Portal vein branch appears as a flow void (dark tubular structure) coursing toward segment IV

  • Surrounded by intermediate liver parenchymal signal

T2-weighted images:

  • Branch appears as a dark flow void

  • Adjacent parenchymal congestion or edema appears hyperintense

STIR:

  • Suppresses fat, improving contrast between vessel lumen and hepatic tissue

  • Useful for detecting parenchymal edema or inflammatory changes

T1 Fat-Saturated (Pre-contrast):

  • Vessel lumen shows intermediate signal intensity, distinguishable against suppressed fat background

T1 Fat-Saturated Post-Contrast (Gadolinium):

  • Enhances brightly in the portal venous phase

  • Clearly shows arborization into segment IVa and IVb branches

  • Useful for evaluating perfusion defects, thrombosis, or tumor infiltration

MRV (Magnetic Resonance Venography):

  • Excellent for mapping portal venous anatomy and variants

  • Shows branch origin (usually left portal vein), bifurcation into IVa/IVb, and drainage territories

  • Critical in living donor evaluation, surgical planning, and portal hypertension

CT Appearance

CT Pre-Contrast:

  • Branch appears as a soft-tissue linear density, difficult to separate from hepatic parenchyma

  • Rarely well-visualized without contrast

CT Post-Contrast:

  • Portal venous phase enhances the branch brightly, clearly defining its course into segment IV

  • Can demonstrate thrombosis, compression, or invasion by tumors

CTV (CT Venography):

  • Provides detailed multiplanar and 3D reconstructions of portal venous anatomy

  • Identifies origin, branching pattern, and segmental perfusion of IVa and IVb

  • Essential in donor hepatectomy, major hepatectomy, and interventional radiology

  • Detects stenosis, occlusion, or collateral formation

CT images

Portal vein branch to liver segment IV CT axial image 1

CT images

Portal vein branch to liver segment IV CT axial image