What is the normal diameter of the external carotid artery (ECA)?

What is the normal diameter of the external carotid artery (ECA)?

• A. 3-4 mm
• B. 4-5 mm
• C. 2-3 mm
• D. 5-6 mm

Answer: (A)

The external carotid artery has a small caliber in adults, reflecting its role in supplying the face and neck through many branches. Its diameter is in the range of a few millimeters, which is smaller than the internal carotid artery that feeds the brain. This small, modest size is the hallmark of a normal ECA on imaging. If you see a clearly larger diameter, it’s not typical for the ECA and may indicate measurement artifact or a different vessel; a diameter that’s too small would also be atypical. Therefore, a modest, small caliber best fits a normal external carotid artery.

The external carotid artery has a small caliber in adults, reflecting its role in supplying the face and neck through many branches. Its diameter is in the range of a few millimeters, which is smaller than the internal carotid artery that feeds the brain. This small, modest size is the hallmark of a normal ECA on imaging. If you see a clearly larger diameter, it’s not typical for the ECA and may indicate measurement artifact or a different vessel; a diameter that’s too small would also be atypical. Therefore, a modest, small caliber best fits a normal external carotid artery.