Abdominal aortic Aneurysm (AAA)

Pathology

• Atherosclerotic changes leads to aneurysmal dilatation of abdominal aorta.
• Calcification of wall can occur.
• Complications
  • Thrombus can form in the lumen
  • Erosion of the adjacent vertebra can occur
  • Rupture with extravasation of blood - chronic or acute
  • Emboli to distal vessels from atheromatous plaques

What imaging studies are available for abdominal aortic aneurysm?

• Ultrasound
  • Screening modality but only measures aortic diameter.
  • For an uncomplicated AAA, ultrasound has a sensitivity and specificity of 97 and 100%.
  • For a leaking or ruptured AAA, sensitivity drops to 4% and specificity remains at 100%.
• CT angiogram
  • Procedure of choice
  • Accurately defines aortic size and extent of aneurysm.
  • CT is the first choice in a patient with a classical midline sharp, tearing abdominal pain that radiates to the back, and has a midline pulsatile mass on exam.
  • CT has a sensitivity and specificity of 97% and 94%.
  • 3D reconstructed images can provide the details necessary for surgical option.
• MRI can provide similar information as a CT angiogram. Difficulty in patient staying still and time of study
• Angiogram: CT angiograms and MRI have replaced the need for angiograms.
• Plain films: Incidental recognition or suspicion of AAA

What are the imaging findings of AAA?

• Widened aortic lumen
  • Plain film:
    • Calcification of both walls at the same level with increased diameter.
      • Displaced calcification of single wall may be due to tortuous undulated aorta.
  • US: Widened aortic lumen > 3 cm
    • Color doppler
  • CT: Dilated aorta
• Calcification of the aneurysm wall
• Complications
  • Thrombus within aneurysm
  • Rupture into
    • Retroperitoneum
    • Perianeurysmal fibrosis obstructing ureter
  • Compression and or erosion of adjacent structures
    • Vertebra
  • Embolic to distal extremities

Atlas of images of abdominal aortic aneurysm

Aneurysm Thoraco abdominal Aorta

Abdominal Aortic Aneurysm Angiogram Click the image for angiogram. It takes about 1 minute initially to download the file.

Abdominal Aortic Aneurysm Ultrasound

CT: Aneurysm of descending Aorta - Eroding Vertebra Abdominal CT and close-up of spine show abdominal aneurysm (A) with chronic erosion (arrows) of adjacent vertebra.

CT: Abdominal Aortic Aneurysm Calcification of wall of the aortic aneurysm

Aneurysm of Abdominal Aorta Plain film Calcification of wall of aortic aneurysm

Is there a role for interventional radiology in the management of AAA?

A permanent stent can be placed in the AAA, thus avoiding surgical risks.This procedure offers an alternative to patients who are of great surgical risk.

A: Abdominal aortic aneurysm Click on the image to see the angiogram.	B: Stent in place Click on the image to see the angiogram.