Abdominal radiologic landmarks

Abdominal Planes & Quadrants - Slicing It Up

• Four Quadrant Model: A simple method using one transverse (transumbilical) and one median plane to create four quadrants: RUQ, LUQ, RLQ, LLQ.

• Key Reference Planes: Used for precise localization in CT/MRI.

Organ & Vessel Landmarks - Find That Organ!

• Aortic Bifurcation: Divides into common iliac arteries at L4 (navel level).
• Celiac Trunk: Arises from the aorta at T12.
  • Supplies foregut organs (stomach, spleen, liver).
• Superior Mesenteric Artery (SMA): Arises just below the celiac trunk at L1.
  • Supplies midgut structures.
• Renal Arteries: Branch from the aorta at L1/L2.
  • Left renal vein passes anterior to the aorta and posterior to the SMA.
• Inferior Mesenteric Artery (IMA): Arises at L3.
  • Supplies hindgut structures.

⭐ Adrenal Glands: The right adrenal gland is typically more pyramidal or triangular and sits superior to the right kidney, while the left is more crescent-shaped and medial to the left kidney.

📌 Retroperitoneal Organs (SAD PUCKER):

• Suprarenal glands
• Aorta/IVC
• Duodenum (2nd-4th parts)
• Pancreas (except tail)
• Ureters
• Colon (ascending/descending)
• Kidneys
• Esophagus
• Rectum

Vertebral Level Landmarks - Spinal Signposts

• T8: Inferior Vena Cava (IVC) passes through the diaphragm.
• T10: Esophagus passes through the diaphragm.
• T12: Aorta passes through the diaphragm (Aortic Hiatus).
  • 📌 Mnemonic: "I 8 10 Eggs At 12" (IVC at T8, Esophagus at T10, Aorta at T12).
• L1: Transpyloric Plane. A key landmark for multiple structures:
  • Pylorus of the stomach, superior mesenteric artery (SMA) origin, renal vessels, neck of the pancreas.
• L2: End of the spinal cord (conus medullaris).
• L3: Origin of the inferior mesenteric artery (IMA).
• L4: Bifurcation of the abdominal aorta.
• L5: Formation of the IVC.

⭐ The L1 transpyloric plane is a high-yield landmark for exams, as it intersects numerous critical structures, including the hila of the kidneys, the neck of the pancreas, and the origin of the SMA.

High‑Yield Points - ⚡ Biggest Takeaways

• Obliteration of the psoas shadow is a critical sign suggesting retroperitoneal pathology.
• The right kidney sits lower than the left, typically spanning vertebral levels T12 to L3.
• The aortic bifurcation into common iliac arteries is a reliable landmark at the L4 level.
• The celiac trunk arises at T12-L1, with the Superior Mesenteric Artery (SMA) just inferiorly at L1.
• The gastric air bubble is normally visible inferior to the left hemidiaphragm.