Topics

Topic

design image
Straight Arteries

The straight arteries of the abdomen, also known as the vasa recta, are terminal arterial branches arising from the arterial arcades of the small intestine. They supply the jejunum and ileum, extending as long, straight vessels from the mesenteric border directly to the intestinal wall.

The jejunum typically contains long, prominent vasa recta, while the ileum contains shorter, more numerous vasa recta due to its multiple tiers of arterial arcades. These vessels are essential for delivering oxygenated blood to the mucosa, submucosa, and muscular layers of the bowel.

Synonyms

  • Vasa recta of small intestine

  • Straight mesenteric arteries

  • Terminal branches of intestinal arcades

Location and Structure

  • Origin: Arise from jejunal and ileal arterial arcades, branches of the superior mesenteric artery (SMA).

  • Course:

    • Proceed nearly straight toward the mesenteric border of the small bowel.

    • Penetrate the muscular wall to supply deeper layers of the intestine.

  • Jejunal pattern: Fewer arcades → long vasa recta.

  • Ileal pattern: Multiple arcades → short, numerous vasa recta.

Relations

  • Anteriorly: Mesenteric fat and small bowel loops

  • Posteriorly: Mesenteric connective tissue and accompanying veins

  • Medially: Superior mesenteric vessels and primary arterial supply

  • Laterally: Serosal surface of jejunum and ileum

Branches

  • Terminal branches penetrate bowel wall to supply:

    • Serosa

    • Muscularis externa

    • Submucosa

    • Mucosa

Function

  • Deliver continuous arterial supply to the jejunal and ileal walls

  • Support nutrient absorption by maintaining mucosal perfusion

  • Provide a direct connection between mesenteric circulation and bowel wall

  • Maintain oxygenation during active peristalsis and metabolic demand

MRI Appearance

T1 Fat-Saturated GRE

  • Arterial lumen: Appears low signal (dark) due to rapid blood flow and flow void characteristics

  • Arterial wall: Thin and typically not visible unless high resolution is used

  • Surrounding fat: Suppressed, improving visibility of vessel contours

  • Vasa recta appearance: Small, linear dark tubular structures radiating toward bowel wall

T2 GRE

  • Flowing blood: Low signal (flow void), giving vessels their dark linear appearance

  • Mesenteric fat: Intermediate signal

  • Bowel wall layers: Display mixed intermediate intensities

  • Vasa recta: Seen as slender dark lines extending from mesentery to intestine

T1 Fat-Saturated Post-Contrast (GRE)

  • Arterial lumen: Bright enhancement with rapid contrast filling

  • Small straight arteries: Appear as thin, enhancing linear vessels

  • Mesenteric background: Fat-suppressed, allowing clear visualization of enhancing vasa recta

  • Bowel wall enhancement pattern: Smooth, symmetric mucosal enhancement around arterial insertion sites

  • Particularly helpful to demonstrate arterial flow continuity from arcades into bowel wall

CT Appearance

Post-Contrast CT (Arterial Phase)

  • Straight arteries (vasa recta): Appear as thin, high-attenuation enhancing linear vessels radiating from mesenteric arterial arcades to the bowel wall

  • Jejunal vasa recta: Longer, more prominent enhancing straight arteries

  • Ileal vasa recta: Shorter, denser network of enhancing small vessels

  • Mesenteric fat: Provides soft-tissue contrast for identifying vessel course

  • Bowel wall: Uniform enhancement outlining insertion points of straight arteries

  • Advantages:

    • Excellent for delineating vascular anatomy

    • High-resolution visualization of arcades and straight artery branching

CT image

Straight Arteries CT axial image-img-00000-00000