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pyloric antrum

The pyloric antrum is the distal portion of the stomach, located between the body of the stomach and the pyloric canal, which leads to the pyloric sphincter and duodenum. It is typically wide and funnel-shaped, serving as a reservoir for gastric contents before they pass through the pylorus. Histologically, the antrum contains mucus-secreting glands and G-cells that produce gastrin, playing a critical role in regulating gastric motility and acid secretion. The antrum’s mucosa is highly folded, adapting to food storage and digestion.

Synonyms

  • Gastric antrum

  • Antrum pyloricum

  • Pyloric region of stomach

Function

  • Serves as a reservoir for partially digested food (chyme)

  • Regulates the passage of gastric contents into the duodenum through coordinated contractions

  • Houses G-cells, which secrete gastrin to stimulate acid production in the stomach body

  • Mixes food with gastric secretions through strong peristaltic contractions

Arterial Supply

  • Right gastric artery (branch of the common hepatic artery)

  • Right gastroepiploic artery (branch of the gastroduodenal artery)

  • Contributions from the left gastric artery

Venous Drainage

  • Drains into the right gastric vein and right gastroepiploic vein

  • These veins empty into the portal vein, making the antrum part of the portal circulation

Nerve Supply

  • Parasympathetic fibers: via the vagus nerve (CN X) → stimulate gastric motility and secretion

  • Sympathetic fibers: via the celiac plexus → inhibit motility and contract pyloric sphincter

MRI Appearance

T1-weighted images:

  • Lumen may contain air (signal void) or fluid/food (variable low to intermediate signal)

  • Gastric wall appears intermediate signal intensity

  • Fatty tissue around the stomach is hyperintense, outlining the wall

T2-weighted images:

  • Gastric wall appears intermediate signal

  • Fluid in the antrum is bright hyperintense, aiding in wall visualization

  • Inflammation or edema causes wall thickening with hyperintense signal

STIR (Short Tau Inversion Recovery):

  • Fat suppression improves visualization of wall edema or infiltrative disease

  • Pathologies such as gastritis, ulcers, or neoplasms appear bright hyperintense relative to the normal wall

T1 Post-Contrast (Gadolinium-enhanced):

  • Normal wall enhances uniformly

  • Gastritis shows diffuse mucosal enhancement

  • Tumors show focal, irregular, or heterogeneous enhancement

  • Ulcers may appear as non-enhancing mucosal defects

CT Appearance

Non-contrast CT:

  • Appears as a soft tissue structure in the epigastric region

  • Lumen may contain air (black) or food residue (soft tissue density)

  • Calcifications are rare but may be present in chronic ulcer disease

Contrast-enhanced CT (CECT):

  • Normal antrum wall is thin and enhances homogeneously

  • Gastritis: diffuse wall thickening with enhancement

  • Neoplasms: asymmetric thickening, irregular enhancement, possible invasion of adjacent structures

  • CT is excellent for assessing gastric outlet obstruction, ulcers, and tumors

MRI image

pyloric antrum anatomy MRI axial image -img-00000-00000

MRI image

pyloric antrum anatomy MRIcoronal image -img-00000-00000

CT image

pyloric antrum anatomy CT axial image -img-00000-00000