Question

What is the investigation of choice for screening of proximal internal carotid artery stenosis?

• A. Doppler flow USG
• B. CT subtraction angiography
• C. MRI
• D. Angiography (DSA)

Hint:

Screening favours the non-invasive bedside test that grades flow velocity.

Answer 1

The Correct Option is A

Step 1: A screening test should be non-invasive, safe, inexpensive and repeatable, while still being able to detect and grade the lesion.

Step 2: Carotid Doppler ultrasonography combines a B-mode image of the vessel wall with Doppler assessment of blood flow velocity. Stenosis at the origin of the internal carotid artery can be both identified and quantified reliably by the rise in flow velocity across the narrowed segment.

Step 3: The alternatives are not first-line screening tools. Digital subtraction angiography (DSA) is invasive and carries a stroke risk, so it is reserved for problem-solving. CT subtraction angiography uses contrast and radiation, and MRI/MR angiography is costlier and less readily available for screening.

Step 4: Hence Doppler flow ultrasonography is the screening investigation of choice for proximal internal carotid stenosis.