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Gallbladder

The gallbladder is a pear-shaped, hollow organ located on the inferior surface of the liver in the gallbladder fossa, between the right and quadrate lobes. It serves as a reservoir for bile, concentrating and releasing it into the duodenum via the cystic duct and common bile duct. The gallbladder typically measures 7–10 cm in length and has a capacity of about 30–50 mL. Structurally, it is divided into the fundus, body, and neck, with the neck continuous with the cystic duct. Its wall contains smooth muscle that contracts under the influence of cholecystokinin (CCK) after food intake, especially fatty meals.

Synonyms

  • Vesica fellea

  • Biliary vesicle

  • Cholecyst

Function

  • Stores bile secreted by the liver

  • Concentrates bile by absorbing water and electrolytes

  • Releases bile into the duodenum for digestion and absorption of fats

  • Plays a role in maintaining biliary pressure regulation

MRI Appearance

T1-weighted images:

  • Gallbladder lumen filled with bile appears low signal intensity (hypointense)

  • Gallbladder wall shows thin, low-to-intermediate signal

  • Gallstones appear as signal voids (very low signal) within the lumen

T2-weighted images:

  • Bile appears hyperintense (bright), providing strong contrast with the hypointense wall

  • Gallstones appear as signal voids with a bright rim of bile surrounding them

  • Wall thickening or pericholecystic fluid (e.g., in cholecystitis) shows hyperintensity

STIR (Short Tau Inversion Recovery):

  • Suppresses fat signal, highlighting edema, inflammation, or pericholecystic fluid

  • Wall thickening or inflammatory changes appear hyperintense

  • Useful for detecting acute cholecystitis or abscesses

T1 Post-Contrast (Gadolinium-enhanced):

  • Gallbladder wall enhances thin and uniform in normal state

  • Pathological conditions (acute cholecystitis, carcinoma) demonstrate irregular or thickened wall enhancement

  • Helpful for differentiating benign vs. malignant gallbladder lesions

CT Appearance

Non-contrast CT:

  • Gallbladder lumen is fluid density (~0–20 HU); gallstones appear hyperdense or iso/hypodense depending on composition

  • Wall is usually thin and not well visualized unless abnormal

  • Calcified gallstones or porcelain gallbladder are hyperdense

Contrast-enhanced CT (CECT):

  • Gallbladder wall enhances thin and smooth in normal patients

  • Abnormalities include wall thickening, mural enhancement, pericholecystic fluid, or intraluminal masses

  • CT is excellent for detecting gallstones, cholecystitis, perforation, and carcinoma

  • Multiplanar reconstructions help evaluate relation to liver and biliary tree

MRI images

Gallbladder anatomy MRI axial image -img-00000-00000

MRI images

Gallbladder anatomy MRI coronal image -img-00000-00000

CT image

Gallbladder anatomy CT axial image -img-00000-00000