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Accessory hepatic vein

The accessory hepatic veins are additional venous channels that drain the liver directly into the inferior vena cava (IVC), independent of the three main hepatic veins (right, middle, and left). These veins are considered anatomical variants but are relatively common, occurring in up to 30–40% of individuals.

The most frequent accessory veins include inferior right hepatic veins that drain segments VI and VII directly into the IVC below the entry of the main right hepatic vein. Others may drain from the caudate lobe or left lobe. Their number, size, and location vary widely among individuals.

Clinically, accessory hepatic veins are highly significant in hepatic resections, living donor liver transplantation, and hepatic venous outflow obstruction syndromes. In surgery, unrecognized accessory veins can lead to uncontrolled bleeding or venous congestion of liver segments. In interventional radiology, they may serve as alternative routes for hepatic venous catheterization.

Synonyms

  • Inferior right hepatic veins (most common type)

  • Accessory liver veins

  • Extra hepatic venous channels

Function

  • Provide additional venous drainage pathways from liver parenchyma to IVC

  • Reduce risk of venous congestion by collateral drainage

  • Clinically important in transplantation, hepatic resection, and venous interventions

MRI Appearance

T1-weighted images:

  • Accessory hepatic veins appear as flow voids (dark tubular structures) within liver parenchyma coursing toward the IVC

  • Best appreciated in axial or coronal planes

T2-weighted images:

  • Appear as dark flow voids against intermediate liver signal

  • Adjacent edema or congestion in pathology may appear hyperintense

STIR:

  • Suppresses fat, improving contrast between hepatic veins and surrounding parenchyma

  • Highlights associated edema or inflammatory change

T1 Fat-Saturated (Pre-contrast):

  • Veins appear as intermediate signal lumens, distinguishable from suppressed fat background

T1 Fat-Saturated Post-Contrast (Gadolinium):

  • Accessory hepatic veins enhance brightly and homogeneously during the venous phase

  • Demonstrates drainage into IVC and differentiates from small intrahepatic vascular structures

MRV (Magnetic Resonance Venography):

  • Non-invasive mapping of hepatic venous anatomy and variants

  • Clearly shows origin, size, and drainage of accessory hepatic veins into the IVC

  • Useful in transplant donor evaluation, venous obstruction, and surgical planning

CT Appearance

CT Pre-Contrast:

  • Accessory hepatic veins appear as linear soft-tissue densities within liver parenchyma

  • Difficult to identify without contrast

CT Post-Contrast:

  • Veins enhance with contrast, draining into IVC below main hepatic veins

  • Best visualized in venous phase (portal and delayed)

CTV (CT Venography):

  • Gold standard for non-invasive assessment of hepatic venous variants

  • Provides detailed 3D reconstructions showing origin, course, and IVC entry points

  • Essential for donor liver evaluation, venous outflow obstruction assessment, and resection planning

CT images

Accessory hepatic vein AXIAL CT anatomy image -img-00000-00000

CT images

Accessory hepatic vein AXIAL CT anatomy image -img-00000-00000_00001

CT images

Accessory hepatic vein coronal CT anatomy image -img-00000-00000

CT images

Accessory hepatic vein coronal CT anatomy image -img-00000-00000_00001

CT images

Accessory hepatic vein SAG CT anatomy image -img-00000-00000