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Superior mesenteric vein

The superior mesenteric vein (SMV) is a major venous trunk of the portal venous system. It originates from tributaries that drain the small intestine (jejunum and ileum), cecum, ascending colon, and transverse colon. It ascends in the mesentery, running to the right of the superior mesenteric artery (SMA) and anterior to the third part of the duodenum and uncinate process of the pancreas.

At the level of the pancreas neck, the SMV unites with the splenic vein to form the portal vein, which delivers nutrient-rich blood to the liver. The SMV receives numerous tributaries, including the jejunal and ileal veins, right colic vein, middle colic vein, ileocolic vein, pancreaticoduodenal veins, and gastrocolic trunk.

Clinically, the SMV is crucial in conditions such as mesenteric venous thrombosis, portal hypertension, bowel ischemia, and pancreatic surgery. It serves as a major landmark in abdominal imaging and hepatobiliary surgery.

Synonyms

  • Vena mesenterica superior

  • SMV

  • Portal venous tributary of small intestine and right colon

Function

  • Collects venous blood from the small intestine, cecum, ascending colon, and transverse colon

  • Joins splenic vein to form the portal vein, directing blood into the liver

  • Plays a vital role in nutrient absorption and delivery to hepatic metabolism

  • Serves as an imaging and surgical landmark in pancreatic and hepatobiliary operations

Tributaries

  • Jejunal and ileal veins

  • Ileocolic vein

  • Right colic vein

  • Middle colic vein

  • Pancreaticoduodenal veins

  • Gastrocolic trunk

MRI Appearance

T1-weighted images:

  • SMV lumen appears as a signal void (black) due to flowing blood

  • Vessel wall seen as thin hypointense rim against mesenteric fat

T2-weighted images:

  • Lumen also appears as a signal void

  • In cases of thrombosis: intraluminal signal varies (acute = high signal, chronic = intermediate/low with collateral formation)

STIR:

  • Fat suppression accentuates the course of the SMV through mesenteric fat

  • Thrombosed segments with surrounding mesenteric edema appear hyperintense

T1 Fat-Saturated (Pre-contrast):

  • Normal SMV lumen: intermediate signal intensity, distinguishable from suppressed fat background

  • Thrombosis appears as abnormal intraluminal signal

T1 Fat-Saturated Post-Contrast (Gadolinium):

  • Enhances brightly and homogeneously with venous phase filling

  • Absence of enhancement or intraluminal filling defect indicates thrombosis or stenosis

MRV (Magnetic Resonance Venography):

  • Depicts entire SMV course and tributaries

  • Excellent for diagnosing mesenteric venous thrombosis, varices, and portal venous anomalies

  • Useful for surgical and transplant planning

CT Appearance

CT Pre-Contrast:

  • SMV appears as a tubular soft-tissue density right of SMA

  • Thrombosis appears as hyperdense filling (acute clot)

CT Post-Contrast:

  • Enhances strongly in venous phase, visible draining into portal vein

  • Detects filling defects (thrombus), vessel narrowing, or extrinsic compression

CTV (CT Venography):

  • Gold standard for non-invasive SMV assessment

  • Provides detailed 3D mapping of SMV and tributaries, confluence with splenic vein, and portal venous anatomy

  • Detects thrombosis, varices, tumor invasion, or congenital variants

  • Crucial for bowel ischemia evaluation, transplant surgery, and hepatobiliary interventions

MRI image

Superior mesenteric vein (SMV) MRI coronal anatomy image -img-00000-00000

CT images

Superior mesenteric vein (SMV) CT axial image 1

CT images

Superior mesenteric vein (SMV) CT axial image 2

CT images

Superior mesenteric vein (SMV) CT axial image

CT images

Superior mesenteric vein (SMV) CT coronal image