Fig 1.

Normal anatomy of the carotid siphon, lateral view DSA (A) and anterior coronal imaging plane TCCS (B) A, C5 (precavernous/ganglionic segment), C4 (inferior carotid siphon), C3 (carotid knee), C2 (upper carotid siphon), and C1 (terminal ICA segment). B, Color coding showing flow toward (red) and away (blue) from the transducer. M1 indicates the first segment of the MCA; A1, the precommunicating segment of the ACA; A2, the postcommunicating segment of the ACA; cA1, the contralateral A1 segment, ICA segments C3/4 and C4/5.