Question:

What’s the difference between extra-cranial carotid circulation and intra-cranial carotid circulation?

Answer:

Extra-cranial carotid circulation refers to imaging of the neck and head outside of the skull – the common carotid, the proximal internal carotid, and non-selective imaging of the external carotid and branches. Intra-cranial carotid circulation includes the distal internal carotid artery and cerebral arteries. The internal carotid artery begins outside of the skull as a cervical (neck) artery and then passes through a hole (foramen) in the skull to become an intracranial/cerebral artery.