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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