Transcranial color-coded duplex sonography of the carotid siphon: the coronal approach.

Transcranial color-coded sonography can assist in the assessment of the carotid siphon segments C1 and C5 employing two standardized coronal image planes. In 32 volunteers mean velocities in the C1 and C5 were 41+/-16 and 30+/-10 (cm/s+/-S.D.), pulsatility indices (PI) 0.92+/-0.22 and 0.93+/-0.27, and resistance indices (RI) 0.58+/-0.08 and 0.55+/-0.12, respectively. Concluding, this technique is useful in assessing the carotid siphon with the most robust parameters being PI and RI requiring further validation by the "gold standard" angiography.