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Superior mesenteric lymph nodes

The superior mesenteric lymph nodes are a large group of lymph nodes located around the origin and course of the superior mesenteric artery (SMA) and its branches. They form one of the principal lymphatic drainage stations of the abdomen. These nodes are embedded within the mesentery of the small intestine and extend along the SMA into the mesenteric root.

Anatomically, they are divided into three major groups:

  • Central nodes: Located around the SMA origin, near the anterior surface of the aorta.

  • Intermediate nodes: Surrounding the main branches of the SMA (ileocolic, right colic, middle colic).

  • Peripheral nodes: Along the distal arterial branches within the mesentery of the jejunum and ileum.

They drain lymph from the jejunum, ileum, cecum, appendix, ascending colon, and transverse colon. From here, lymph flows into the intestinal lymph trunk and then into the cisterna chyli → thoracic duct.

Clinically, these nodes are crucial in oncology: they are commonly involved in small bowel tumors, appendiceal carcinoma, cecal carcinoma, and mesenteric lymphomas. They are also a key station in surgical resections such as right hemicolectomy, and in staging of gastrointestinal malignancies.

Synonyms

  • Mesenteric lymph nodes

  • SMA lymph nodes

  • Intestinal mesenteric nodes

Function

  • Drain lymph from the jejunum, ileum, cecum, appendix, ascending colon, and transverse colon

  • Filter lymph and participate in immune surveillance

  • Serve as sentinel nodes in oncological staging

  • Form a major pathway toward the cisterna chyli and thoracic duct

MRI Appearance

T1-weighted images:

  • Normal nodes appear as low to intermediate signal intensity ovoid structures within mesenteric fat

  • Fat around nodes is hyperintense, helping delineation

T2-weighted images:

  • Nodes appear as intermediate to mildly hyperintense structures

  • Enlarged or necrotic nodes show heterogeneous T2 hyperintensity

STIR:

  • Fat suppression highlights lymph nodes against mesenteric fat

  • Reactive or malignant nodes may appear hyperintense

T1 Fat-Saturated Post-Contrast (Gadolinium):

  • Normal nodes enhance mildly and homogeneously

  • Malignant or necrotic nodes show heterogeneous or peripheral rim enhancement

  • Detects pathological vascularity in metastatic disease or lymphoma

MRI Non-Contrast 3D Imaging:

  • Useful in providing a volumetric map of nodal stations relative to SMA branches

  • Helpful in pre-surgical planning and oncology staging

CT Appearance

CT Pre-Contrast:

  • Nodes appear as soft tissue density nodules within mesenteric fat

  • Small nodes (<1 cm) may be difficult to differentiate from vessels without contrast

CT Post-Contrast:

  • Normal nodes enhance homogeneously

  • Malignant nodes may show heterogeneous enhancement, necrotic centers, or conglomerate masses

  • CT identifies nodal size, distribution, and relationship to SMA and mesenteric vessels

CT Venography (CTV):

  • Useful for evaluating vascular invasion or compression by enlarged lymph nodes

  • Provides 3D reconstructions to assess oncological spread, lymphadenopathy, and surgical planning

MRI image

Superior mesenteric lymph nodes MRI coronal image anatomy image -img-00000-00000

CT images

Superior mesenteric lymph nodes CT axial imag

CT images

Superior mesenteric lymph nodes CT coronal imag 1