MCQ – 35518

Correct Answer » B Explanation

Aortic dissection occurs when a tear develops in the intima of the aorta, allowing blood to enter the media and create a false lumen.

Typical presentation:

• Sudden severe “tearing” or “ripping” chest pain
• Pain radiating to the back
• Pulse deficits
• Blood pressure differences between limbs

Why Option B is Correct

CT Angiography (CTA) is currently the investigation of choice in most patients with suspected aortic dissection because it is:

• Rapid
• Widely available
• Highly sensitive and specific
• Able to identify:
  • Intimal flap
  • True and false lumens
  • Extent of dissection
  • Branch vessel involvement

Sensitivity and specificity are both typically >95%.

Why Other Options are Incorrect

A. Ultrasonography (USG)

• Routine abdominal or chest ultrasound is not adequate.
• Transesophageal echocardiography (TEE) can diagnose dissection, especially in unstable patients, but is not represented by the option “USG.”

C. MRI

• Extremely accurate.
• Excellent sensitivity and specificity.
• Limitation:
  • Time-consuming
  • Less available in emergencies
  • Not suitable for unstable patients

Historically considered the most accurate test, but not the practical investigation of choice in acute settings.

D. Digital Subtraction Angiography (DSA)

• Previously considered the gold standard.
• Largely replaced by CT angiography due to its invasive nature and lower speed.