Topics

Topic

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Liver

The liver is the largest internal organ and gland in the human body, located in the right upper quadrant of the abdomen, beneath the diaphragm. It is divided anatomically into right, left, caudate, and quadrate lobes, and functionally into eight Couinaud segments, each with its own vascular inflow, outflow, and biliary drainage. The liver performs vital metabolic, synthetic, detoxification, and storage functions, and plays a central role in digestion through the production and secretion of bile.

Synonyms

  • Hepar

  • Hepatic organ

  • Glandula hepatica

Function

  • Metabolism: of carbohydrates, lipids, and proteins

  • Detoxification: neutralizes toxins and drugs

  • Bile production: essential for fat digestion and absorption

  • Storage: of glycogen, vitamins (A, D, B12), and iron

  • Synthesis: of plasma proteins (albumin, clotting factors)

  • Immune role: via Kupffer cells filtering bacteria and antigens

Arterial Supply

  • Hepatic artery proper, a branch of the common hepatic artery (from celiac trunk)

  • Supplies 20–30% of hepatic blood flow, rich in oxygen

Venous Drainage

  • Hepatic veins (right, middle, and left) drain into the inferior vena cava

  • Portal venous inflow: supplies 70–80% of blood (nutrient-rich from GI tract via portal vein)

Nerve Supply

  • Parasympathetic: from the vagus nerve (CN X) via the celiac plexus

  • Sympathetic: from the celiac plexus and thoracic splanchnic nerves

  • Provides autonomic regulation of hepatic blood flow and bile secretion

MRI Appearance

T1-weighted images:

  • Normal parenchyma: homogeneous intermediate signal intensity

  • Vessels and bile ducts: hypointense against the liver background

  • Fatty infiltration: increased T1 signal

  • Fibrosis, tumor, or edema: low signal intensity

T2-weighted images:

  • Normal liver: homogeneous intermediate signal intensity

  • Fluid collections, cysts, or bile ducts: hyperintense (bright)

  • Tumors and edema: often hyperintense compared to background parenchyma

STIR (Short Tau Inversion Recovery):

  • Suppresses fat signal, useful for detecting inflammatory changes, edema, or infiltrative disease

  • Lesions (tumors, abscesses, cysts) appear hyperintense relative to parenchyma

T1 Post-Contrast (Gadolinium-enhanced):

  • Arterial phase: hypervascular lesions (e.g., HCC, hemangiomas) enhance

  • Portal venous phase: uniform parenchymal enhancement; hypovascular lesions appear darker

  • Delayed phase: fibrotic or cirrhotic tissue retains contrast longer

  • Useful for lesion characterization and vascular mapping

CT Appearance

Non-contrast CT:

  • Liver parenchyma appears homogeneous, soft tissue density (~55–65 HU)

  • Fatty liver: lower attenuation compared to spleen

  • Calcifications, stones, or hyperdense lesions may be seen

Contrast-enhanced CT (CECT):

  • Arterial phase: highlights hepatic artery supply and hypervascular lesions

  • Portal venous phase: optimal for detecting hypovascular lesions and metastases

  • Delayed phase: shows fibrotic changes and lesion washout

  • CT is essential for lesion detection, vascular anatomy, trauma evaluation, and surgical planning

MRI images

Liver mr anatomyi image

CT image

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MRI IMAGE

Liver MRI CORONAL image -img-00000-00000