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Superior rectal artery

The superior rectal artery (SRA) is the terminal branch of the inferior mesenteric artery (IMA) and the principal arterial supply to the proximal rectum. It arises from the IMA as it descends into the pelvis, crossing the left common iliac vessels, and enters the pelvic cavity within the mesorectum.

The artery divides into right and left branches, which further split into smaller branches that penetrate the rectal wall, supplying the mucosa, submucosa, and muscular layers. These branches anastomose inferiorly with the middle rectal arteries (from internal iliac arteries) and the inferior rectal arteries (from the internal pudendal arteries), forming an extensive rectal vascular network.

Clinically, the SRA is important in hemorrhoidal disease, rectal cancer surgery, ischemic colitis, and interventional embolization. It is also a key vascular structure preserved or controlled during low anterior resection and abdominoperineal resection.

Synonyms

  • Arteria rectalis superior

  • Terminal branch of IMA

  • Hemorrhoidal artery (proximal portion)

Function

  • Supplies blood to the proximal rectum and superior portion of the anal canal

  • Contributes to rectal vascular plexus with middle and inferior rectal arteries

  • Critical for maintaining mucosal perfusion and collateral circulation in the rectum

MRI Appearance

T1-weighted images:

  • Superior rectal artery appears as a thin flow void (black lumen) within mesorectal fat

  • Surrounded by hyperintense perirectal fat, improving vessel delineation

T2-weighted images:

  • Lumen appears as a signal void

  • In rectal inflammation, adjacent edema highlights vessel margins

STIR:

  • Fat suppression improves contrast with mesorectal fat

  • Perivascular edema or inflammation appears hyperintense, especially in rectal cancer or proctitis

T1 Fat-Saturated (Pre-contrast):

  • Lumen may show intermediate signal intensity standing out against suppressed fat background

  • Useful for distinguishing vessels from adjacent lymph nodes

T1 Fat-Saturated Post-Contrast (Gadolinium):

  • Artery enhances brightly and homogeneously, tracing its course into the rectal wall

  • Helps demonstrate tumor neovascularity, ischemia, or inflammatory hyperemia

MRA (Magnetic Resonance Angiography):

  • Clearly demonstrates the origin from the IMA, its descent into the mesorectum, and branching into rectal wall

  • Useful in vascular mapping, embolization planning, or ischemia assessment

CT Appearance

CT Pre-Contrast:

  • Appears as a linear soft-tissue density in the mesorectal fat, not well visualized without contrast

  • Calcified atherosclerotic plaques may be detected at origin in older patients

CT Post-Contrast:

  • Enhances brightly, showing its descent and branching into rectal wall

  • Useful for detecting rectal hyperemia, ischemia, or active GI bleeding

CT Angiography (CTA):

  • Best modality for non-invasive vascular detail

  • Shows origin from IMA, mesorectal course, bifurcation into right and left branches, and rectal wall penetration

  • 3D reconstructions demonstrate rectal vascular network and anastomoses

  • Essential for evaluating GI hemorrhage, ischemic colitis, rectal tumors, and surgical planning

MRI images

Superior rectal artery coronal mri anatomy image -img-00000-00000

MRI images

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CT images

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CT images

Superior rectal artery AXIAL CT anatomy image -img-00000-00000_00001

CT images

Superior rectal artery CORONAL CT anatomy image -img-00000-00000

CT VRT 3D image

superior rectal artery CT 3D VRT anatomy image

MRI image

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MRI image

superior rectal artery MRI axial image MRI axial anatomy image-img-00000-00000_00001

CT image

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