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Topic

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Liver Segment I – Caudate lobe

The caudate lobe (Segment I) is a small but functionally unique liver segment located on the posterior liver surface, between the inferior vena cava (IVC) on the right and the ligamentum venosum fissure on the left. It borders the porta hepatis inferiorly and extends superiorly toward the hepatic veins.

Unlike other liver segments, the caudate lobe has dual blood inflow from both right and left portal veins and hepatic arteries, and independent venous outflow directly into the IVC through multiple small caudate veins. This unique vascular independence explains why the caudate often hypertrophies in cirrhosis and may be spared in hepatic diseases.

Clinically, it is vital in oncology, transplantation, hepatic resections, and Budd–Chiari syndrome, where venous outflow is obstructed.

Synonyms

  • Segment I of the liver

  • Caudate lobe

  • Lobus caudatus hepatis

Function

  • Performs all major hepatic functions (metabolic, detoxification, synthetic, and storage)

  • Serves as a compensatory lobe due to independent blood supply and drainage

  • Plays a diagnostic role in cirrhosis, hepatic venous outflow obstruction, and focal lesions

Nerve Supply

  • Hepatic plexus (parasympathetic vagus fibers + sympathetic fibers from celiac plexus)

Arterial Supply

  • Branches from both right and left hepatic arteries

Venous Drainage

  • Portal inflow from right and left portal veins

  • Outflow: direct small caudate veins into the IVC, independent of main hepatic veins

MRI Appearance and Signal

T1-weighted images:

  • Normal caudate parenchyma is intermediate signal,

  • Fat around ligamentum venosum helps define the left border

T2-weighted images:

  • Normal parenchyma shows intermediate to mildly hyperintense signal

  • Lesions such as cysts and hemangiomas appear bright hyperintense

STIR:

  • Fat suppression improves contrast

  • Edema, inflammation, or infiltrative lesions in caudate stand out as bright hyperintense areas

T1 Fat-Saturated (Pre-contrast):

  • Normal caudate shows intermediate parenchymal signal, distinct from suppressed fat planes

T1 Fat-Saturated Post-Contrast (Dynamic Gadolinium):

  • Arterial phase: rapid homogeneous enhancement (like other segments)

  • Portal venous phase: homogeneous enhancement matches background liver

  • Delayed phase: uniform washout; focal lesions may show persistent or altered enhancement

MRI Non-Contrast 3D Imaging:

  • Provides detailed mapping of caudate borders, IVC relation, and ligamentum venosum fissure

  • Used in pre-surgical liver mapping

Triple-Phase MRI (Dynamic Contrast Imaging):

  • Arterial phase: caudate enhances briskly, well-demarcated from hypodense lesions (e.g., HCC, hypervascular mets)

  • Portal venous phase: homogeneous enhancement with the rest of liver

  • Delayed phase: iso- to slightly hyperintense relative to parenchyma; fibrosis may show persistent enhancement

CT Appearance

CT Pre-Contrast:

  • Caudate appears isoattenuating to other hepatic parenchyma

  • Borders clearly outlined by IVC and ligamentum venosum

CT Post-Contrast (Single Phase):

  • Enhances similarly to the rest of liver parenchyma

  • Pathology (HCC, metastasis) shows hyper/hypo enhancement patterns

Triple-Phase CT (Liver Protocol):

  • Arterial phase: normal caudate enhances homogeneously; hypervascular tumors (HCC, NET metastases) appear hyperdense

  • Portal venous phase: caudate appears isoattenuating; hypovascular lesions (mets, cholangiocarcinoma) become more conspicuous

  • Delayed phase: uniform attenuation in normal tissue; fibrosis, cholangiocarcinoma, or scar tissue may show delayed enhancement

MRI image

Liver Segment I – Caudate lobe MRI axial anatomy image

CT image

Liver Segment I – Caudate lobe CT axial anatomy image

CT image

Liver Segment I – Caudate lobe CT axial anatomy image