Imaging

Abdominal Aortic Aneurysm

Preliminary Diagnosis: Abdominal Aortic Aneurysm

I. What imaging technique is first-line for this diagnosis?

CT with contrast/CT angiogram

II. Describe the advantages and disadvantages of this technique for diagnosis of abdominal aortic aneurysm.

Advantages

  • Distinguishes residual lumen from mural thrombus, leaking or ruptured aneurysm

  • Delineates branch vessel anatomy

  • Good for evaluation after endovascular repair

Disadvantages

  • Exposure to ionizing radiation

III. What are the contraindications for the first-line imaging technique?

  • Relative contraindications include pregnancy,

  • Absolute contraindication to administer contrast if decreased renal function (i.e., <1.6 or depending on institution)

IV. What alternative imaging techniques are available?

  • Plain abdominal radiograph

  • CT without contrast

  • MRI/MRA

  • Ultrasound

  • Digital substraction angiography (DSA)

V. Describe the advantages and disadvantages of the alternative techniques for diagnosis of abdominal aortic aneurysm.

Plain abdominal radiograph

Advantages

  • Inexpensive

  • Relatively quick procedure

Disadvantages

  • Not very sensitive or specific

  • Limited diagnostic utility

CT without contrast

Advantages

  • Quick

  • Relatively inexpensive

  • Can be diagnostic

  • Can identify acute hemorrhage

Disadvantages

  • Exposed to ionizing radiation

  • Lacks detail provided by IV contrast

MRI/MRA

Advantages

  • Useful in endoleak detection

  • Diagnostic

Disadvantages

  • Expensive

  • Time consuming

  • Requires significant patient cooperation to minimize motion artifact

  • Not as specific as CTA or CT with contrast

Ultrasound

Advantages

  • Can be diagnostic

  • Can identify thrombus

  • Color Doppler can identify residual lumen

Disadvantages

  • Often not as specific as other imaging techniques

  • Limited by body habitus and overlying bowel gas

Digital subtraction angiography (DSA)

Advantages

  • Shows relationship of aneurysm to branch vessels

Disadvantages

  • Can underestimate true aneurysm size

  • Exposure to ionizing radiation

  • Expensive

  • Time consuming

  • Operator dependent

  • Invasive

VI. What are the contraindications for the alternative imaging techniques?

Plain abdominal radiograph

  • Relative contraindication if patient is pregnant

CT without contrast

  • Relative contraindication if patient is pregnant

MRI/MRA

  • Non-MR-compatible metallic hardware

Ultrasound

  • No significant contraindication

DSA

  • Relative contraindication if patient is pregnant.

  • Absolute contraindication to administer contrast if decreased renal function (i.e., <1.6 or depending on institution)

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